Statement of Stockholders' Equity [Abstract] Statement [Table] Statement [Table] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Statement [Line Items] Statement [Line Items] Dividends to common stockholders per share Common Stock, Dividends, Per Share, Cash Paid Document and Entity Information [Abstract] Document and Entity Information [Abstract] Document Type Document Type Amendment Flag Amendment Flag Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Trading Symbol Trading Symbol Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Voluntary Filers Entity Current Reporting Status Entity Current Reporting Status Entity Public Float Entity Public Float Consolidated Balance Sheets Parenthetical [Abstract] Consolidated Balance Sheets Parenthetical [Abstract] Property, Plant and Equipment by Type [Axis] Property, Plant and Equipment by Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Building and Building Improvements [Member] Building and Building Improvements [Member] Assets: Assets [Abstract] Real Estate Investment Property, Accumulated Depreciation Real Estate Investment Property, Accumulated Depreciation Intangible lease assets, accumulated amortization Finite-Lived Intangible Assets, Accumulated Amortization Tenant receivables, allowance for doubtful accounts Allowance for Doubtful Accounts Receivable Deferred financing costs, accumulated amortization Accumulated Amortization, Deferred Finance Costs Deferred lease costs, accumulated amortization Deferred Costs, Leasing, Accumulated Amortization Liabilities: Liabilities [Abstract] Intangible lease liabilities, accumulated amortization Intangible Lease Liabilities, Accumulated Amortization The amount of accumulated amortization related to the acquisition of an off-market lease when the terms of the lease are unfavorable to the market terms for the lease at the date of acquisition. Stockholders' Equity: Stockholders' Equity Attributable to Parent [Abstract] Shares-in-trust, shares authorized (in shares) Shares In Trust Authorized Shares In Trust Authorized Shares-in-trust, shares outstanding (in shares) Shares In Trust Outstanding Shares In Trust Outstanding Preferred stock, par value (in dollars per share) Preferred Stock, Par or Stated Value Per Share Preferred stock, shares authorized (in shares) Preferred Stock, Shares Authorized Preferred stock, shares outstanding (in shares) Preferred Stock, Shares Outstanding Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Common stock, shares authorized (in shares) Common Stock, Shares Authorized Common stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Line of Credit and Notes Payable [Abstract] Line of Credit and Notes Payable [Abstract] Schedule of Debt Schedule of Debt [Table Text Block] Schedule of Maturities of Long-term Debt Schedule of Maturities of Long-term Debt [Table Text Block] Equity Method Investments and Joint Ventures [Abstract] Schedule of Equity Method Investments Schedule of Equity Method Investments [Table Text Block] Variable Interest Entities [Abstract] Variable Interest Entities [Abstract] Variable Interest Entities Variable Interest Entity, Similar Entity Aggregation, Description Tenant Receivables [Abstract] Tenant Receivables [Abstract] Tenant Receivables Tenant Receivables [Text Block] The entire disclosure for all tenant receivables and straight-line rent receivables of the reporting entity. Real Estate and Accumulated Depreciation Disclosure [Abstract] Schedule III - Real Estate Assets and Accumulated Depreciation Real Estate and Accumulated Depreciation Disclosure [Text Block] Organization [Abstract] Organization Abstract Schedule of Real Estate Properties [Table] Schedule of Real Estate Properties [Table] Real Estate Properties By Type [Axis] Real Estate Properties By Type [Axis] Real Estate Properties By Type [Axis] Real Estate Properties Type [Domain] Real Estate Properties Type [Domain] Real Estate Properties Type [Domain] Office properties [Member] Office properties [Member] Office properties [Member] Building [Member] Building [Member] Industrial buildings [Member] Industrial buildings [Member] Industrial buildings [Member] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Unconsolidated Joint Venture [Member] Unconsolidated Joint Venture [Member] Unconsolidated Joint Venture [Member] Real Estate Properties [Line Items] Real Estate Properties [Line Items] Number Of Wholly Owned Subsidiaries Number Of Wholly Owned Management Subsidiaries Number Of Wholly Owned Management Subsidiaries Number of Real Estate Properties Number of Real Estate Properties Number of Metropolitan Areas Number of Metropolitan Areas In Which Entity Operates Number of Metropolitan Areas In Which Entity Operates Square Footage of Real Estate Property Square Footage of Real Estate Property Real Estate Properties Leased, Percent Real Estate Properties Leased, Percent Real Estate Properties Leased Percent Accounting Policies [Abstract] Significant Accounting Policies [Table] Significant Accounting Policies [Table] Significant Accounting Policies [Table] Derivative Instrument Risk [Axis] Derivative Instrument Risk [Axis] Derivative Contract Type [Domain] Derivative Contract Type [Domain] Interest Rate Swap [Member] Interest Rate Swap [Member] Interest Rate Cap [Member] Interest Rate Cap [Member] Significant Accounting Policies [Line Items] Significant Accounting Policies [Line Items] Significant Accounting Policies [Line Items] Use of Estimates, Policy Use of Estimates, Policy [Policy Text Block] Real Estate Assets, Policy Real Estate Assets [Policy Text Block] Describes the accounting policy pertaining to long-lived real estate assets, both tangible and intangible, which are held-for-use; and the methods for depreciating or amortizing such assets. Business Combinations Policy Business Combinations Policy [Policy Text Block] Investments in Unconsolidated Joint Ventures, Policy Investments In Unconsolidated Joint Ventures [Policy Text Block] Disclosure of accounting policy for investment in unconsolidated joint ventures or partnerships that are included in the enterprise's financial statements using the equity method of accounting. Cash and Cash Equivalents, Policy Cash and Cash Equivalents, Policy [Policy Text Block] Tenant Receivables Net, Policy Tenant Receivables Net [Policy Text Block] Disclosure of accounting policy for tenant receivables, net of allowance for doubtful accounts. Notes Receivables, Policy Receivables, Policy [Policy Text Block] Restricted Cash and Escrows, Policy Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block] Prepaid Expenses and Other Assets, Policy Prepaid Expenses and Other Assets [Policy Text Block] Disclosure of accounting policy for prepaid and other assets. Goodwill, Policy Goodwill and Intangible Assets, Policy [Policy Text Block] Deferred Financing Costs, Policy Deferred Charges, Policy [Policy Text Block] Deferred Lease Costs, Policy Lease, Policy [Policy Text Block] Line of Credit and Notes Payable, Policy Debt, Policy [Policy Text Block] Interest Rate Derivatives, Policy Derivatives, Policy [Policy Text Block] Stockholders' Equity, Policy Stockholders' Equity, Policy [Policy Text Block] Noncontrolling Interest, Policy Noncontrolling Interest [Policy Text Block] Disclosure of accounting policy for noncontrolling interests. Revenue Recognition, Policy Revenue Recognition, Policy [Policy Text Block] Stock-based Compensation, Policy Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block] Legal Fees, Policy Legal Costs, Policy [Policy Text Block] Net Income Available to Common Stockholders Per Share, Policy Earnings Per Share, Policy [Policy Text Block] Comparability of Prior Year Financial Data, Policy [Policy Text Block] Comparability of Prior Year Financial Data, Policy [Policy Text Block] Income Tax, Policy Income Tax, Policy [Policy Text Block] Leases [Abstract] Schedule of Future Minimum Rental Payments for Operating Leases Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Unconsolidated Joint Ventures Equity Method Investments Disclosure [Text Block] Supplemental Cash Flow Elements [Abstract] Schedule of Cash Flow, Supplemental Disclosures Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Income Tax Disclosure [Abstract] Schedule of Tax Basis Income Schedule of Tax Basis Income [Table Text Block] Schedule of reconciliation between GAAP basis financial statement net income and Income Tax basis net income, prior to dividends paid deduction. Schedule of Characterization Of Dividends To Common Stockholders Schedule of Characterization Of Dividends To Common Stockholders [Table Text Block] Schedule of characterization of dividends to common stockholders between ordinary income, capital gains, and return of capital. Derivative Instruments [Abstract] Derivative Instruments [Abstract] Derivative Instruments Derivative Instruments and Hedging Activities Disclosure [Text Block] Schedule of Variable Interest Entities Schedule of Variable Interest Entities [Table Text Block] Discontinued Operations [Abstract] Discontinued Operations [Abstract] Discontinued Operations Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] Commitments and Contingencies Disclosure [Abstract] Loss Contingencies [Table] Loss Contingencies [Table] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Maximum [Member] Maximum [Member] Major Property Class [Axis] Major Property Class [Axis] Major Property Class [Domain] Major Property Class [Domain] Land [Member] Land [Member] Long-term and Short-term Debt, Type [Axis] Long-term and Short-term Debt, Type [Axis] Long-term and Short-term Debt, Type [Axis] Long-term and Short-term Debt, Type [Domain] Long-term and Short-term Debt, Type [Domain] Long-term and Short-term Debt, Type [Domain] Secured Debt [Member] Secured Debt [Member] Unsecured Debt [Member] Unsecured Debt [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] $500 Million Unsecured Facility [Member] Unsecured 500Million Facility [Member] Unsecured 500Million Facility [Member] Letter of Credit Agreements by Expiration Date [Axis] Letter of Credit Agreements by Expiration Date [Axis] Letter of Credit Agreements by Expiration Date [Axis] Letter of Credit Agreements by Expiration Date [Domain] Letter of Credit Agreements by Expiration Date [Domain] Letter of Credit Agreements by Expiration Date [Domain] Letter Of Credit August 2012 [Member] Letter Of Credit August 2012 [Member] Letter Of Credit August 2012 [Member] Letter of Credit 2, February 2012 [Member] Letter of Credit 2, February 2012 [Member] Letter of Credit 2, February 2012 [Member] Letter of Credit, December 2012 [Member] Letter of Credit, December 2012 [Member] Letter of Credit, December 2012 [Member] Letter Of Credit, June 2012 [Member] Letter Of Credit June 2012 [Member] Letter Of Credit June 2012 [Member] Loss Contingencies by Nature of Contingency [Axis] Loss Contingencies by Nature of Contingency [Axis] Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Collectibility of Tenant Reimbursements [Member] Collectibility of Tenant Reimbursements [Member] Collectibility of Tenant Reimbursements [Member] Pending or Threatened Litigation [Member] Pending or Threatened Litigation [Member] Loss Contingencies [Line Items] Loss Contingencies [Line Items] Commitment to Provide Funding to Tenants for Capital Improvements Commitment to Provide Funding to Tenants for Capital Improvements Commitment to Provide Funding to Tenants for Capital Improvements Loss Contingency, Loss in Period Loss Contingency, Loss in Period Debt Instrument, Face Amount Debt Instrument, Face Amount Letters of Credit Outstanding, Amount Letters of Credit Outstanding, Amount Letter of Credit Renewal Period Letter of Credit Renewal Period Letter of Credit Renewal Period Property Subject to or Available for Operating Lease, Number of Units Property Subject to or Available for Operating Lease, Number of Units Operating Leases, Future Minimum Payments Due [Abstract] Operating Leases, Future Minimum Payments Due [Abstract] 2012 Operating Leases, Future Minimum Payments Due, Current 2013 Operating Leases, Future Minimum Payments, Due in Two Years 2014 Operating Leases, Future Minimum Payments, Due in Three Years 2015 Operating Leases, Future Minimum Payments, Due in Four Years 2016 Operating Leases, Future Minimum Payments, Due in Five Years Thereafter Operating Leases, Future Minimum Payments, Due Thereafter Total Operating Leases, Future Minimum Payments Due Operating Leases, Rent Expense Operating Leases, Rent Expense Property Subject to or Available for Operating Lease, Net Property Subject to or Available for Operating Lease, Net Number of Lawsuits as Defendant Number of Lawsuits as Defendant Number of Lawsuits as Defendant Loss Contingency, Damages Sought, Value Loss Contingency, Damages Sought, Value Estimated Insurance Recoveries Estimated Insurance Recoveries Loss Contingency, Range of Possible Loss, Minimum Loss Contingency, Range of Possible Loss, Minimum Loss Contingency, Range of Possible Loss, Maximum Loss Contingency, Range of Possible Loss, Maximum Derivative [Table] Derivative [Table] $300 Million Unsecured Term Loan [Member] Unsecured 300 Million Term Loan [Member] $300 Million Unsecured Term Loan [Member] $250 Million Unsecured Term Loan [Member] Unsecured 250Million Term Loan [Member] Unsecured 250Million Term Loan [Member] 500 W. Monroe Mezzanine I Loan- A Participation $45 Million [Member] Mezzanine I Loan-A Participation, 500 W. Monroe Building [Member] W. Monroe, 500 Mezzanine I Loan-A Participation [Member] $140.0 Million 500 W. Monroe Mortgage Loan [Member] Mortgage Loan, 500 W. Monroe Building [Member] W. Monroe, 500 Mortgage Loan [Member] Derivative Instruments, Gain (Loss) by Income Statement Location [Axis] Derivative Instruments, Gain (Loss) by Income Statement Location [Axis] Income Statement and Other Comprehensive Income (Loss) Location [Domain] Interest Expense [Member] Interest Expense [Member] Interest Rate Contract [Member] Interest Rate Contract [Member] Interest Rate Swap 1 [Member] Interest Rate Swap 1 [Member] Interest Rate Swap 2 [Member] Interest Rate Swap 2 [Member] Interest Rate Swap 3 [Member] Interest Rate Swap 3 [Member] Interest Rate Swap 4 [Member] Interest Rate Swap 4 [Member] Interest Rate Cap 1 [Member] Interest Rate Cap 1 [Member] Interest Rate Cap 1 [Member] Interest Rate Cap 2 [Member] Interest Rate Cap 2 [Member] Interest Rate Cap 2 [Member] Credit Risk Contract [Member] Credit Risk Contract [Member] Derivative [Line Items] Derivative [Line Items] Number of Interest Rate Derivatives Held Number of Interest Rate Derivatives Held Increase (Decrease) in Fair Value of Interest Rate Fair Value Hedging Instruments Increase (Decrease) in Fair Value of Interest Rate Fair Value Hedging Instruments Notional Amount Notional Amount of Interest Rate Cash Flow Hedge Derivatives Amount of loss recognized in OCI on derivative Unrealized Gain (Loss) on Interest Rate Cash Flow Hedges, Pretax, Accumulated Other Comprehensive Income (Loss) Amount of previously recorded loss reclassified from accumulated OCI into interest expense Interest Rate Cash Flow Hedge Gain (Loss) Reclassified to Earnings, Net Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net Assets Needed for Immediate Settlement, Aggregate Fair Value Assets Needed for Immediate Settlement, Aggregate Fair Value Stock Based Compensation [Abstract] Stock Based Compensation [Abstract] Stock Based Compensation Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Equity [Abstract] Number of Classes of Common Stock Number of Classes of Common Stock Number of Classes of Common Stock Summary of Significant Accounting Policies Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies [Text Block] Quarterly Financial Information Disclosure [Abstract] Revenues Revenues Real estate operating income Operating Income (Loss) Discontinued operations Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest Net income attributable to Parent Net Income (Loss) Attributable to Parent Basic earnings per share Earnings Per Share, Basic Diluted earnings per share Earnings Per Share, Diluted Dividends per share Notes Receivable [Abstract] Notes Receivable [Abstract] Notes Receivable and Variable Interest Entity [Table] Notes Receivable and Variable Interest Entity [Table] Notes Receivable and Variable Interest Entity [Table] Mezzanine I Loan-A Participation, 500 W. Monroe Building [Member] Component of Other Income, Nonoperating [Axis] Component of Other Income, Nonoperating [Axis] Component of Other Income, Nonoperating, Name [Domain] Component of Other Income, Nonoperating, Name [Domain] Operating Cash Flow On Foreclosed Property [Member] Operating Cash Flow On Foreclosed Property [Member] Operating Cash Flow On Foreclosed Property [Member] Notes Receivable [Line Items] Notes Receivable [Line Items] Notes Receivable [Line Items] Number of Investments Number of Investments Number of Investments Number of Notes Receivable Matured Number of Notes Receivable Matured Number of Notes Receivable Matured Number of Notes Receivable Number of Notes Receivable Number of Notes Receivable Variable Interest Entity, Initial Consolidation, Gain (Loss) Variable Interest Entity, Initial Consolidation, Gain (Loss) Other Nonoperating Income Other Nonoperating Income Schedule of Disposal Groups, Including Discontinued Operations, Results Of Operations Schedule of Disposal Groups, Including Discontinued Operations, Results Of Operations [Table Text Block] Schedule of Disposal Groups, Including Discontinued Operations, Results Of Operations [Table Text Block] Schedule of Disposal Groups, Including Discontinued Operations, Income Statement, Balance Sheet and Additional Disclosures Schedule of Disposal Groups, Including Discontinued Operations, Income Statement, Balance Sheet and Additional Disclosures [Table Text Block] Statement of Cash Flows [Abstract] Cash Flows from Operating Activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Operating distributions received from unconsolidated joint ventures Equity Method Investment, Dividends or Distributions Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Income attributable to noncontrolling interest- discontinued operations Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Noncontrolling Interest Depreciation Depreciation Amortization of deferred financing costs and fair market value adjustments on notes payable Amortization of Financing Costs and Discounts Other amortization Amortization of Intangible Assets Impairment loss on real estate assets Asset Impairment Charges Gain on extinguishment of debt Gains (Losses) on Extinguishment of Debt, Actual Cash Impact Gains (Losses) on Extinguishment of Debt, Actual Cash Impact Accretion of discount on notes receivable Accretion (Amortization) of Discounts and Premiums, Investments Stock compensation expense Share-based Compensation Equity in income of unconsolidated joint ventures Income (Loss) from Equity Method Investments, Actual Cash Impact Income (Loss) from Equity Method Investments, Actual Cash Impact Gain on consolidation of variable interest entity (Gain)/loss on sale of real estate assets Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax Changes in assets and liabilities: Increase (Decrease) in Operating Assets [Abstract] Increase in tenant receivables, net Increase (Decrease) in Accounts Receivable Decrease/(increase) in restricted cash and escrows Increase (Decrease) in Restricted Cash for Operating Activities Increase in prepaid expenses and other assets Increase (Decrease) in Prepaid Expense and Other Assets Increase in accounts payable and accrued expenses Increase (Decrease) in Accounts Payable and Accrued Liabilities (Decrease)/increase in deferred income Increase (Decrease) in Deferred Revenue Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Cash Flows from Investing Activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Investments in real estate assets and related intangibles Payments to Acquire Productive Assets Cash assumed upon consolidation of variable interest entity Assets Assumed Upon Consolidation Of Variable Interest Entity Net assets received as cash upon consolidation of a variable interest entity ("VIE"). Investment in mezzanine debt Payments to Acquire Receivables Net sales proceeds from wholly-owned properties and consolidated joint venture Proceeds from Divestiture of Businesses, Net of Cash Divested Net sales proceeds received from unconsolidated joint ventures Proceeds from Sale of Equity Method Investments Investments in unconsolidated joint ventures Payments to Acquire Equity Method Investments Liquidation of noncontrolling interest upon sale of consolidated joint venture Payments to Noncontrolling Interests Deferred lease costs paid Increase (Decrease) in Lease Acquisition Costs Net cash provided by/(used in) investing activities Net Cash Provided by (Used in) Investing Activities Cash Flows from Financing Activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Deferred financing costs paid Payments of Financing Costs Proceeds from line of credit and notes payable Proceeds from Notes Payable Repayments of line of credit and notes payable Repayments of Notes Payable Net proceeds from/(costs of) issuance of common stock Proceeds from Issuance of Common Stock Repurchases of common stock as part of announced program Payments for Repurchase of Common Stock Redemptions of common stock Payments for Redemptions of Common Stock Payments for Redemptions of Common Stock Dividends paid to stockholders and distributions to noncontrolling interest Payments of Dividends Common Stock, Distributions To Noncontrolling Interest and Discount on Dividend Reinvestment Sum of a) The cash outflow from the distribution of an entity's earnings in the form of dividends to common stockholders, and b) Distributions to noncontrolling interest, and c)Discount on dividend reinvestments. Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities Net increase/(decrease) in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents, beginning of period Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents, end of period Notes Receivable Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Operating Leases Leases of Lessor Disclosure [Text Block] Statement of Financial Position [Abstract] Assets: Land Land Buildings and improvements, less accumulated depreciation of $792,342 and $744,756 as of December 31, 2011 and December 31, 2010, respectively Investment Building and Building Improvements, Net Investment Building and Building Improvements, Net Intangible lease assets, less accumulated amortization of $119,419 and $145,742 as of December 31, 2011 and December 31, 2010, respectively Finite-Lived Intangible Assets, Net Construction in progress Construction in Progress, Gross Total real estate assets Real Estate Investment Property, Net Investments in unconsolidated joint ventures Equity Method Investments Cash and cash equivalents Tenant receivables, net of allowance for doubtful accounts of $631 and $1,298 as of December 31, 2011 and December 31, 2010, respectively Tenant Receivables Including Straight Line Rental Revenue Receivables Tenant Receivables Including Straight Line Rental Revenue Receivables Notes receivable Notes, Loans and Financing Receivable, Net Due from unconsolidated joint ventures Due from Joint Ventures Restricted cash and escrows Restricted Cash and Cash Equivalents Prepaid expenses and other assets Prepaid Expense and Other Assets Goodwill Goodwill Deferred financing costs, less accumulated amortization of $9,214 and $11,893 as of December 31, 2011 and December 31, 2010, respectively Deferred Finance Costs, Net Deferred lease costs, less accumulated amortization of $120,358 and $137,726 as of December 31, 2011 and December 31, 2010, respectively Deferred Costs, Leasing, Net Total assets Assets Line of credit and notes payable Notes Payable Accounts payable, accrued expenses, and accrued capital expenditures Accounts Payable and Accrued Liabilities Deferred income Deferred Revenue Intangible lease liabilities, less accumulated amortization of $63,981 and $84,308 as of December 31, 2011 and December 31, 2010, respectively Off-market Lease, Unfavorable Interest rate swaps Interest Rate Cash Flow Hedge Liability at Fair Value Total liabilities Liabilities Commitments and Contingencies Commitments and Contingencies Reedemable Common Stock Temporary Equity, Carrying Amount Shares-in-trust, 150,000,000 shares authorized; none outstanding as of December 31, 2011 or December 31, 2010 Common Stock Held in Trust Preferred stock, no par value, 100,000,000 shares authorized, none outstanding as of December 31, 2011 or December 31, 2010 Preferred Stock, Value, Issued Common stock, $.01 par value, 750,000,000 shares authorized, 172,629,748 shares issued and outstanding as of December 31, 2011; and 172,658,489 shares issued and outstanding as of December 31, 2010 Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital, Common Stock Cumulative distributions in excess of earnings Accumulated Distributions in Excess of Net Income Other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Piedmont stockholders' equity Stockholders' Equity Attributable to Parent Noncontrolling interest Stockholders' Equity Attributable to Noncontrolling Interest Total stockholders' equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Total liabilities and stockholders' equity Liabilities and Equity Impairment of Certain Real Estate Assets [Abstract] Impairment of Certain Real Estate Assets [Abstract] Schedule of Impaired Long-Lived Assets Held and Used [Table] Schedule of Impaired Long-Lived Assets Held and Used [Table] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value, Inputs, Level 3 [Member] Fair Value, Inputs, Level 3 [Member] Impaired Long-Lived Assets Held and Used by Type [Axis] Impaired Long-Lived Assets Held and Used by Type [Axis] Impaired Long-Lived Assets Held and Used, Asset Name [Domain] Impaired Long-Lived Assets Held and Used, Asset Name [Domain] Auburn Hills Corporate Center Building [Member] Auburn Hills Corporate Center Building [Member] Auburn Hills Corporate Center Building [Member] 1111 Durham Avenue Building [Member] Durham Avenue 1111 [Member] Durham Avenue 1111 [Member] 1441 West Long Lake Road Building [Member] West Long Lake Road 1441 [Member] West Long Lake Road 1441 [Member] Impaired Long-Lived Assets Held and Used [Line Items] Impaired Long-Lived Assets Held and Used [Line Items] Real Estate Investment Property, Net Impairment losses on real estate assets Impairment of Real Estate Impairment loss on real estate assets Disposal Group, Including Discontinued Operation, Loss on Write Down Disposal Group Including Discontinued Operation Loss on Write Down Real Estate Investment Property, Fair Value Real Estate Investment Property, Fair Value Real estate investment property, adjusted fair value for impairment recognized. Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangement by Share-based Payment Award, Award Type and Plan Name [Axis] Schedule of Share-based Compensation Arrangement by Share-based Payment Award, Award Type and Plan Name [Axis] Share-based Compensation Arrangements by Share-based Payment Award, Award Type and Plan Name [Domain] Share-based Compensation Arrangements by Share-based Payment Award, Award Type and Plan Name [Domain] Stock Awards [Member] Stock Awards [Member] Stock Awards [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Stock Awards, Performance Period Used In Calculation Stock Awards, Performance Period Used In Calculation Stock Awards, Performance Period Used In Calculation Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Allocated Share-based Compensation Expense Allocated Share-based Compensation Expense Share Based Compensation Arrangement By Share Based Payment Award, Equity Instruments Other Than Options, Amortization Of Nonvested Shares Share Based Compensation Arrangement By Share Based Payment Award, Equity Instruments Other Than Options, Amortization Of Nonvested Shares Share Based Compensation Arrangement By Share Based Payment Award, Equity Instruments Other Than Options, Amortization Of Nonvested Shares Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition Commitments and Contingencies [Abstract] Commitments and Contingencies Abstract Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Income Statement [Abstract] Revenues: Revenues [Abstract] Rental income Operating Leases, Income Statement, Lease Revenue Tenant reimbursements Tenant Reimbursements Property management fee revenue Management Fees Revenue Other rental income Gain (Loss) on Contract Termination Total revenues Expenses: Operating Expenses [Abstract] Property operating costs Direct Costs of Leased and Rented Property or Equipment Depreciation Depreciation, Continuing Operations The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives, from continuing operations. Amortization Adjustment for Amortization, Continuing Operations The aggregate amount of recurring noncash expense charged against earnings in the period to allocate the cost of assets over their estimated remaining economic lives, from continuing operations. General and administrative General and Administrative Expense Operating Expenses Operating Expenses Real estate operating income Other income (expense): Nonoperating Income (Expense) [Abstract] Interest expense Interest Expense Interest and other income Equity in income of unconsolidated joint ventures Income (Loss) from Equity Method Investments Gain on consolidation of variable interest entity Gain on extinguishment of debt Gains (Losses) on Extinguishment of Debt Nonoperating Income (Expense) Nonoperating Income (Expense) Income from continuing operations Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest Discontinued operations: Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent [Abstract] Operating income, excluding impairment loss Disposal Group, Including Discontinued Operation, Operating Income (Loss) Impairment loss Gain/(loss) on sale of real estate assets Income from discontinued operations Less: Net income attributable to noncontrolling interest Income (Loss) from Continuing Operations Attributable to Noncontrolling Interest Net income attributable to Piedmont Per share information – basic: Earnings Per Share, Basic [Abstract] Income from continuing operations Income (Loss) from Continuing Operations, Per Basic Share Income from discontinued operations Income (Loss) from Discontinued Operations, Net of Tax, Per Basic Share Income attributable to noncontrolling interest Income (Loss) from Continuing Operations Attributable to Noncontrolling Interest, Per Basic Share Income (Loss) from Continuing Operations Attributable to Noncontrolling Interest, Per Basic Share Net income available to common stockholders Per share information – diluted: Earnings Per Share, Diluted [Abstract] Income from continuing operations Income (Loss) from Continuing Operations, Per Diluted Share Income from discontinued operations Income (Loss) from Discontinued Operations, Net of Tax, Per Diluted Share Income attributable to noncontrolling interest Income (Loss) from Continuing Operations Attributable to Noncontrolling Interest, Per Diluted Share Income (Loss) from Continuing Operations Attributable to Noncontrolling Interest, Per Diluted Share Net income available to common stockholders Weighted-average common shares outstanding - basic (in shares) Weighted Average Number of Shares Outstanding, Basic Weighted-average common shares outstanding - diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Component of Other Operating Cost and Expense, General [Axis] Component of Other Operating Cost and Expense, General [Axis] Component of Other Operating Cost and Expense, Name [Domain] Component of Other Operating Cost and Expense, Name [Domain] Common Area Maintenance Costs [Member] Common Area Maintenance Costs [Member] Common Area Maintenance Costs [Member] Deferred Revenue Arrangement Type [Axis] Deferred Revenue Arrangement Type [Axis] Deferred Revenue Arrangement Type [Domain] Deferred Revenue Arrangement Type [Domain] Below Market Leases [Member] Below Market Leases [Member] Below Market Leases [Member] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Above-Market In-Place Lease Assets [Member] Above Market Leases [Member] Above Market Leases [Member] Absorption Period Costs [Member] Absorption Period Costs [Member] Absorption Period Costs [Member] Lease Origination Costs [Member] Lease Origination Costs [Member] Lease Origination Costs [Member] Piedmont Office Holdings, Inc [Member] Piedmont Office Holdings, Inc [Member] Piedmont Office Holdings, Inc [Member] Consolidated Joint Venture [Member] Consolidated Joint Venture [Member] Consolidated Joint Venture [Member] Building Improvements [Member] Building Improvements [Member] Land Improvements [Member] Land Improvements [Member] Furniture, fixtures, and equipment [Member] Furniture and Fixtures [Member] Minimum [Member] Minimum [Member] Number Of Unconsolidated Joint Venture Partnerships Number Of Unconsolidated Joint Venture Partnerships Number Of Unconsolidated Joint Venture Partnerships Property, Plant and Equipment, Useful Life, Average Property, Plant and Equipment, Useful Life, Average Property, Plant and Equipment, Useful Life, Minimum Property, Plant and Equipment, Useful Life, Minimum Property, Plant and Equipment, Useful Life, Maximum Property, Plant and Equipment, Useful Life, Maximum Finite-Lived Intangible Assets, Gross Finite-Lived Intangible Assets, Gross Finite-Lived Intangible Liabilities, Gross Finite-Lived Intangible Liabilities, Gross Finite-Lived Intangible Liabilities, Gross Amortization expense related to Intangible Lease Origination Costs and Absorption Period Costs: Amortization Of Intangible Lease Origination Costs And Absorption Period Costs Amortization Of Intangible Lease Origination Costs And Absorption Period Costs Amortization of Above-Market and Below-Market In-Place Lease intangibles as a net increase to rental revenues: Amortization Of Above And Below Market Leases Amortization of above and below Market Leases Finite-Lived Intangible Assets, Future Amortization Expense [Abstract] Finite-Lived Intangible Assets, Future Amortization Expense [Abstract] 2012 Future Amortization Expense, Year One 2013 Future Amortization Expense, Year Two 2014 Future Amortization Expense, Year Three 2015 Future Amortization Expense, Year Four 2016 Future Amortization Expense, Year Five Thereafter Future Amortization Expense, after Year Five Total Finite-Lived Intangible Assets, Future Amortization Expense 2012 Deferred Revenue, Amortization Year One Deferred Revenue, Amortization Year One 2013 Deferred Revenue, Amortization Year Two Deferred Revenue, Amortization Year Two 2014 Deferred Revenue, Amortization Year Three Deferred Revenue, Amortization Year Three 2015 Deferred Revenue, Amortization Year Four Deferred Revenue, Amortization Year Four 2016 Deferred Revenue, Amortization Year Five Deferred Revenue, Amortization Year Five Thereafter Deferred Revenue, Amortization, Thereafter Deferred Revenue, Amortization, Thereafter Total Deferred Revenue, Amortization Deferred Revenue, Amortization Weighted-Average Amortization Period (in years) Finite-Lived Intangible Assets, Weighted-Average Useful Life Weighted-Average Amortization Period (in years) Finite-Lived Intangible Liabilities, Weighted-Average Useful Life Finite-Lived Intangible Liabilities, Weighted-Average Useful Life Original Maturity Of Investments Accounted For As Cash Equivalents Original Maturity Of Investments Accounted For As Cash Equivalents Original Maturity Of Investments Accounted For As Cash Equivalents Valuation Allowances and Reserves, Recoveries Valuation Allowances and Reserves, Recoveries Provision for Doubtful Accounts Provision for Doubtful Accounts Amortization of deferred financing costs and fair market value adjustments on notes payable Amortization of Financing Costs Amortization of deferred lease costs Amortization of Deferred Leasing Fees Amortization of Lease Incentive Amortization of Lease Incentives Amortization of Lease Incentives Amortization of Debt Discount (Premium) Amortization of Debt Discount (Premium) Stock Repurchase Program, Authorized Amount Stock Repurchase Program, Authorized Amount Stock Repurchased and Retired During Period, Shares Stock Repurchased and Retired During Period, Shares Real Estate Investment Trust Status Required Taxable Income Distribution Rate Real Estate Investment Trust Status Required Taxable Income Distribution Rate Real Estate Investment Trust Status Required Taxable Income Distribution Rate Income Tax Expense (Benefit) Income Taxes Paid Dividend Reinvestment Plan, Shareholders Discount Dividend Reinvestment Plan, Shareholders Discount Dividend Reinvestment Plan, Shareholders Discount Schedule of Debt Instruments [Table] Schedule of Debt Instruments [Table] Schedule of Debt Instruments [Table] Interest Rate by Type [Axis] Interest Rate by Type [Axis] Interest Rate by Type [Axis] Interest Rate, Type [Domain] Interest Rate, Type [Domain] Interest Rate, Type [Domain] Base Rate [Member] Base Rate [Member] Base Rate [Member] LIBOR [Member] LIBOR [Member] LIBOR [Member] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Repayment of Debt [Member] Piedmont 500 West Monroe Mezz I LLC [Member] Piedmont 500 West Monroe Mezz I LLC [Member] $45.0 Million Fixed-Rate Loan [Member] Fixed-Rate 45Million Loan [Member] Fixed-Rate 45Million Loan [Member] $120.0 Million 35 West Wacker Drive Mortgage Note [Member] Mortgage Note, 35 West Wacker Building [Member] Mortgage Note, 35 West Wacker Building [Member] $200.0 Million Mortgage Note [Member] Aon Center Chicago 4.87 Mortgage Note [Member] Aon Center Chicago 4.87 Mortgage Note [Member] $25.0 Million Mortgage Note [Member] Aon Center Chicago 5.70 Mortgage Note [Member] Aon Center Chicago 5.70 Mortgage Note [Member] $350.0 Million Secured Pooled Facility [Member] Secured Pooled Facility [Member] Secured Pooled Facility [Member] $105.0 Million Fixed-Rate Loan [Member] Fixed-Rate 105Million Loan [Member] Fixed-Rate 105Million Loan [Member] $125.0 Million Fixed-Rate Loan [Member] Fixed-Rate 125Million Loan [Member] Fixed-Rate 125Million Loan [Member] $42.5 Million Fixed-Rate Loan [Member] Fixed-Rate 42.5Million Loan [Member] Fixed-Rate 42.5Million Loan [Member] $140 Million WDC Mortgage Notes [Member] WDC Mortgage Notes [Member] WDC Mortgage Notes [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Repayments of Secured Debt Repayments of Secured Debt Gains (Losses) on Extinguishment of Debt Debt Instrument, Interest Rate, Effective Percentage Debt Instrument, Interest Rate, Effective Percentage Derivative, Cap Interest Rate Derivative, Cap Interest Rate Write off of Deferred Debt Issuance Cost Write off of Deferred Debt Issuance Cost Line Of Credit Facility Extension Period Line Of Credit Facility Extension Period Line Of Credit Facility Extension Period Line of Credit Facility, Extension Fee Percentage Line of Credit Facility, Extension Fee Percentage Line of Credit Facility, Extension Fee Percentage Option to Request Establishment of New Term Loan Commitments, Aggregate Amount Option to Request Establishment of New Term Loan Commitments, Aggregate Amount Option to Request Establishment of New Term Loan Commitments, Aggregate Amount Option to Request Establishment of New Term Loan Commitments, Request Amount Option to Request Establishment of New Term Loan Commitments, Minimum Per Occurrence Option to Request Establishment of New Term Loan Commitments, Minimum Per Occurrence Option to Request Establishment of New Term Loan Commitments, Number of Requests Option to Request Establishment of New Term Loan Commitments, Number of Requests Option to Request Establishment of New Term Loan Commitments, Number of Commitments Option to Request Establishment of New Term Loan Commitments, Number of Commitments Option to Request Establishment of New Term Loan Commitments, Number of Commitments Debt Instrument, Maturity Term Debt Instrument, Maturity Term Rate Debt Instrument, Interest Rate, Stated Percentage Debt Weighted Average Interest Rate Excluding Discontinued Operation Debt Weighted Average Interest Rate Excluding Discontinued Operation Reflects the calculation as of the balance sheet date, excluding notes payable held for sale, of the average interest rate weighted by the amount of secured debt outstanding by type or by instrument at that time. Line of credit and notes payable, outstanding Notes and Loans Payable Debt, Weighted Average Interest Rate Debt, Weighted Average Interest Rate Debt Instrument, Basis Spread on Variable Rate Debt Instrument, Basis Spread on Variable Rate LIBOR Interest Rate In Effect LIBOR Interest Rate In Effect LIBOR Interest Rate In Effect Debt Instrument, Description of Variable Rate Basis Debt Instrument, Description of Variable Rate Basis Prime Rate In Effect Prime Rate In Effect Company-specific short term borrowing rate. Interest Payments on Debt Facilities Interest Paid, Net Maturities of Long-term Debt [Abstract] 2012 Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months 2013 Long-term Debt, Maturities, Repayments of Principal in Year Two 2014 Long-term Debt, Maturities, Repayments of Principal in Year Three 2015 Long-term Debt, Maturities, Repayments of Principal in Year Four 2016 Long-term Debt, Maturities, Repayments of Principal in Year Five Thereafter Long-term Debt, Maturities, Repayments of Principal after Year Five Total Long-term Debt Recapitalization, Listing and Offering of Common Stock Stockholders' Equity Note Disclosure [Text Block] Impairment of Certain Real Estate Assets Asset Impairment Charges [Text Block] Net income Depreciation and amortization expense for financial reporting purposes in excess of amounts for income tax purposes Income Reconciliation, Nondeductible Expense, Depreciation and Amortization Income Reconciliation, Nondeductible Expense, Depreciation and Amortization Rental income accrued for income tax purposes less than amounts for financial reporting purposes Income Reconciliation, Deductions, Rental Income Accrued Income Reconciliation, Deductions, Rental Income Accrued Net amortization of above/below-market lease intangibles for financial reporting purposes in excess of amounts for income tax purposes Income Reconciliation, Deductions, Net Amortization Of Lease Intangibles Income Reconciliation, Deductions, Net Amortization Of Lease Intangibles Gain on disposal of property for financial reporting purposes in excess of amounts for income tax purposes Income Reconciliation, Gain On Disposal Of Property Income Reconciliation, Deductions, Gain On Disposal Of Property Taxable income of Piedmont Washington Properties, Inc., in excess of amount for financial reporting purposes Income Reconciliation, Taxable Income Income Reconciliation, Taxable Income Other expenses for financial reporting purposes in excess of amounts for income tax purposes Income Reconciliation, Nondeductible Expense, Other Expenses Income Reconciliation, Nondeductible Expense, Other Expenses Income tax basis net income, prior to dividends paid deduction Income Tax Basis Net Income Prior To Dividends Paid Deduction Income Tax Basis Net Income Prior To Dividends Paid Deduction Ordinary income Common Stock Dividends, Ordinary Income, Percent Common Stock Dividends, Ordinary Income, Percent Capital gains Common Stock Dividends, Capital Gains, Percent Common Stock Dividends, Capital Gains, Percent Return of capital Common Stock Dividends, Return Of Capital, Percent Common Stock Dividends, Return Of Capital, Percent Common Stock Dividends, Percent Common Stock Dividends, Percent Common Stock Dividends, Percent Tax Basis Of Total Assets Tax Basis Of Total Assets Tax Basis Of Total Assets Liability for Uncertain Tax Positions, Noncurrent Liability for Uncertain Tax Positions, Noncurrent Income Tax Examination, Penalties and Interest Expense Income Tax Examination, Penalties and Interest Expense Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Schedule of Equity Method Investment, Equity Method Investee, Name [Axis] Equity Method Investee, Name [Domain] Equity Method Investee, Name [Domain] Fund XIII And REIT Joint Venture [Member] Fund XIII And REIT Joint Venture [Member] Fund XII REIT and Joint Venture [Member] Fund XII REIT and Joint Venture [Member] Fund Xl Xll and REIT Joint Venture [Member] Fund Xl Xll and REIT Joint Venture [Member] Wells Fremont Associates [Member] Wells Fremont Associates [Member] Fund IX, X, XI and REIT Joint Venture [Member] Fund IX, X, XI and REIT Joint Venture [Member] Investment [Line Items] Equity Method Investment, Ownership Percentage Equity Method Investment, Ownership Percentage Equity Method Investments Equity Method Investment, Sale Price of Real Estate Sold Sale Price of Real Estate Sold Sale Price of Real Estate Sold Equity Method Investment, Realized Gain (Loss) on Disposal Equity Method Investment, Realized Gain (Loss) on Disposal Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Table] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Table] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Axis] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Axis] Disposal Groups, Including Discontinued Operations, Name [Domain] Disposal Groups, Including Discontinued Operations, Name [Domain] Sylvan Avenue 111 Building [Member] Sylvan Avenue 111 Building [Member] Sylvan Avenue 111 Building [Member] Eastpointe Corporate Center [Member] Eastpointe Corporate Center [Member] Eastpointe Corporate Center [Member] Corporate Court 5000 [Member] Corporate Court 5000 [Member] Corporate Court 5000 [Member] W Wacker Building 35 [Member] W Wacker Building 35 [Member] W Wacker Building 35 [Member] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Net Sales Proceeds Percent of Ownership Interest In Real Estate Property Disposal Percent of Ownership Interest In Real Estate Property Disposal Percent of Ownership Interest In Real Estate Property Disposal Rental Income Disposal Group, Including Discontinued Operation, Rental Income Disposal Group, Including Discontinued Operation, Rental Income Tenant Reimbursement Disposal Group, Including Discontinued Operation, Tenant Reimbursement Disposal Group, Including Discontinued Operation, Tenant Reimbursement Lease termination income Disposal Group, Including Discontinued Operation, Lease Termination Income Disposal Group, Including Discontinued Operation, Lease Termination Income Revenue Disposal Group, Including Discontinued Operation, Revenue Expenses: Expenses [Abstract] Expenses [Abstract] Property operating costs Disposal Group, Including Discontinued Operation, Property Operating Costs Disposal Group, Including Discontinued Operation, Property Operating Costs Depreciation Disposal Group, Including Discontinued Operation, Depreciation Disposal Group, Including Discontinued Operation, Depreciation Amortization of deferred leasing costs Disposal Group, Including Discontinued Operation, Amortization Disposal Group, Including Discontinued Operation, Amortization General and administrative expense Disposal Group, Including Discontinued Operation, General and Administrative Expense Disposal Group, Including Discontinued Operation, General and Administrative Expense Expenses Disposal Group, Including Discontinued Operation, Operating Expense Other income (expense): Other Income and Expenses [Abstract] Interest expense Disposal Group, Including Discontinued Operation, Interest Expense Interest and other income Disposal Group Including Discontinued Operation Interest And Other Income Expense Disposal Group Including Discontinued Operation Interest And Other Income Expense Net income attributable to noncontrolling interest Other income (expense) Disposal Group Including Discontinued Other Income Expense Disposal Group Including Discontinued Other Income Expense Operating income, excluding impairment loss and gain on sale Gain/(loss) on sale of real estate assets Income from discontinued operations Earnings Per Share [Abstract] Weighted-average common shares – basic (in shares) Restricted stock awards (in shares) Incremental Common Shares Attributable to Share-based Payment Arrangements Weighted-average common shares – diluted (in shares) Supplemental Disclosures of Noncash Activities Cash Flow, Supplemental Disclosures [Text Block] Schedule of Weighted Average Number of Shares Schedule of Weighted Average Number of Shares [Table Text Block] Acquisitions [Abstract] Acquisitions [Abstract] Schedule of Business Acquisitions, by Acquisition Schedule of Business Acquisitions, by Acquisition [Table Text Block] Acquisitions Business Combination Disclosure [Text Block] Accrued capital expenditures and deferred lease costs Increase Decrease In Accrued Capital Expenditures AndDeferred Lease Costs Net change in the balance of accrued lease acquisition costs and accrued capital expenditures during the period. These accrued costs consist of items such as leasing commissions, lease incentives, procurement fees, tenant improvements, and/or general building improvements. Change in accrued offering costs related to issuance of common stock Increase (Decrease) in Deferred Offering Costs Change in specific incremental costs directly attributable to a proposed or actual offering of securities which are deferred at the end of the reporting period. Net assets assumed upon consolidation of variable interest entity, net of notes receivable previously recorded Net Assets Assumed Upon Consolidation Of Variable Interest Entity, Net Of Notes Receivable Previously Recorded Net Assets within a variable interest entity ("VIE") structure assumed at estimated fair market value, net of notes receivable previously recorded. Liabilities assumed upon consolidation of variable interest entity Liabilities Assumed Upon Consolidation Of Variable Interest Entity Liabilities within a variable interest entity ("VIE") structure assumed at estimated fair market value. Discounts applied to issuance of common stock Stock Issued in Noncash Activities, Discounts Applied Stock Issued in Noncash Activities, Discounts Applied Discounts reduced as result of redemptions of common stock Increase (Decrease) In Discounts Due To Redemptions Of Common Stock Increase (Decrease) In Discounts Due To Redemptions Of Common Stock Redeemable common stock Redeemable Common Stock Value Change in redeemable common stock value during the period. Stock Awards, Granted May 6, 2009 [Member] Stock Awards, Granted May 6, 2009 [Member] Stock Awards, Granted May 6, 2009 [Member] Stock Awards, Granted May 11, 2010 [Member] Stock Awards, Granted May 11, 2010 [Member] Stock Awards, Granted May 11, 2010 [Member] Stock Awards 1, Granted May 24, 2010 [Member] Stock Awards 1, Granted May 24, 2010 [Member] Stock Awards 1, Granted May 24, 2010 [Member] Stock Awards 2, Granted May 24, 2010 [Member] Stock Awards 2, Granted May 24, 2010 [Member] Stock Awards 2, Granted May 24, 2010 [Member] Stock Awards, Granted April 5, 2011 [Member] Stock Awards, Granted April 5, 2011 [Member] Stock Awards, Granted April 5, 2011 [Member] Stock Awards 2, Granted April 5, 2011 [Member] Stock Awards 2, Granted April 5, 2011 [Member] Stock Awards 2, Granted April 5, 2011 [Member] Rollforward of deferred stock award activity Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward] Unvested Deferred Stock Awards at beginning of year (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Deferred Stock Awards Granted During Fiscal Year 2011 (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Deferred Stock Awards Vested During Fiscal Year 2011 (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Deferred Stock Awards Forfeited During Fiscal Year 2011 (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Unvested Deferred Stock Awards at end of year (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward] Unvested Deferred Stock Awards, Weighted-Average Grant Date Fair Value at beginning of year Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Deferred Stock Awards Granted During Fiscal Year 2011, Weighted-Average Grant Date Fair Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Deferred Stock Awards Vested During Fiscal Year 2011, Weighted-Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Deferred Stock Awards Forfeited During Fiscal Year 2011, Weighted Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period, Weighted Average Grant Date Fair Value Unvested Deferred Stock Awards, Weighted-Average Grant Date Fair Value at end of year Net Shares Granted Share Based Compensation Arrangement By Share Based Payment Award, Equity Instruments Other Than Options, Net Shares Granted The number of share grants, net of shares surrended for taxes, made on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). Grant Date Fair Value Unvested Shares (in shares) Of the shares granted, % vested Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested Percent At Reported Date Share Based Compensation Arrangement By Share Based Payment Award, Equity Instruments Other Than Options, Vested Percent At Reported Date Of the shares granted, % expected to vest within one year Share Based Compensation Arrangement By Share Based Payment Award, Equity Instruments Other Than Options, Expected to Vest Within One Year, Percent Share Based Compensation Arrangement By Share Based Payment Award, Equity Instruments Other Than Options, Expected to Vest Within One Year, Percent Of the shares granted, % expected to vest in two years Share Based Compensation Arrangement By Share Based Payment Award, Equity Instruments Other Than Options, Expected to Vest In Two Years, Percent Share Based Compensation Arrangement By Share Based Payment Award, Equity Instruments Other Than Options, Expected to Vest In Two Years, Percent Of the shares granted, % expected to vest in three years Share Based Compensation Arrangement By Share Based Payment Award, Equity Instruments Other Than Options, Expected to Vest In Three Years, Percent Share Based Compensation Arrangement By Share Based Payment Award, Equity Instruments Other Than Options, Expected to Vest In Three Years, Percent Schedule Of Tenant Receivables Schedule Of Tenant Receivables [Table Text Block] Schedule Of Tenant Receivables [Table Text Block] Subsequent Events [Abstract] Subsequent Events Subsequent Events [Text Block] Details of Impairment of Long-Lived Assets Held and Used by Asset Details of Impairment of Long-Lived Assets Held and Used by Asset [Table Text Block] Fair Value, Assets Measured on Nonrecurring Basis, Unobservable Input Reconciliation Fair Value, Assets Measured on Nonrecurring Basis, Unobservable Input Reconciliation [Table Text Block] Tabular disclosure of the fair value measurement of assets on nonrecurring basis using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes during the period attributable to the following: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets) and gains or losses recognized in other comprehensive income, and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (2) purchases, sales, issuances, and settlements (each type disclosed separately); and (3) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs), by class of asset. 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[Domain] Real Estate Properties [Axis] Real Estate Properties [Axis] Real Estate Properties [Domain] Real Estate Properties [Domain] Wholly Owned Properties [Member] Wholly Owned Properties [Member] Partially Owned Properties [Member] Partially Owned Properties [Member] Variable Interest Entities by Classification of Entity [Axis] Variable Interest Entities by Classification of Entity [Axis] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Classification [Domain] Eye Street 1225 NW Associates LLC [Member] Eye Street 1225 NW Associates LLC [Member] Eye Street 1225 NW Associates LLC [Member] Eye Street 1201 NW Associates LLC [Member] Eye Street 1201 NW Associates LLC [Member] Eye Street 1201 NW Associates LLC [Member] Interlocken Building 360 [Member] Interlocken Building 360 [Member] Interlocken Building 360 [Member] Kato Road 47300 Building [Member] Kato Road 47300 Building [Member] Kato Road 47300 Building [Member] 1225 Equity LLC [Member] 1225 Equity LLC 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Monroe Fee LLC [Member] Piedmont 500 W. Monroe Fee LLC [Member] Piedmont 500 W. 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net of allowance for doubtful accounts of $631 and $1,298 as of December 31, 2011 and 2010, respectively Accounts Receivable, Net Cumulative rental revenue recognized on a straight-line basis in excess of cash received in accordance with lease terms Deferred Rent Receivables, Net Tenant receivables Schedule of Notional Amounts of Outstanding Derivative Positions Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block] Schedule of Derivative Instruments, Effect on Other Comprehensive Income (Loss) Schedule of Derivative Instruments, Effect on Other Comprehensive Income (Loss) [Table Text Block] Schedule of Finite-Lived Intangible Assets by Major Class Schedule of Finite-Lived Intangible Assets by Major Class [Table Text Block] Amortization Of Intangible Lease Costs Amortization Of Intangible Lease Costs [Table Text Block] Amortization Of Intangible Lease Costs [Table Text Block] Schedule of Finite-Lived Intangible Assets, Future Amortization Expense Schedule 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Financing [Member] Dividend Declared [Member] Dividend Declared [Member] Subsequent Event [Line Items] Subsequent Event [Line Items] Dividends declared (in dollars per share) Common Stock, Dividends, Per Share, Declared Organization Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Statement, Equity Components [Axis] Statement, Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common Stock [Member] Common Stock [Member] Additional Paid-In Capital [Member] Additional Paid-in Capital [Member] Cumulative Distributions in Excess of Earnings [Member] Retained Earnings [Member] Redeemable Common Stock [Member] Redeemable Common Stock [Member] Redeemable Common Stock [Member] Other Comprehensive Loss [Member] Accumulated Other Comprehensive Income (Loss) [Member] Non-controlling Interest [Member] Noncontrolling Interest [Member] Balance, value Balance (in shares) Stock repurchases as part of announced program (See Note 2) Stock Repurchased and Retired During Period, Value Stock repurchases as part of announced program (see Note 2) (in shares) Issuance of common stock Stock Issued During Period, Value, New Issues Issuance of common stock (in shares) Stock Issued During Period, Shares, New Issues Redemptions of common stock Stock Redeemed or Called During Period, Value Redemptions of common stock (in shares) Stock Redeemed or Called During Period, Shares Redeemable common stock Additional Paid In Capital, Change In Redeemable Common Stock Outstanding The change in the value reclassified as Redeemable Common Stock. Offering costs associated with issuance of common stock Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs Attribution of asset sales proceeds to noncontrolling interest Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Dividends ($1.2600 per share),distributions to noncontrolling interest, and dividends reinvested Dividends, Minority Interest (Decrease) From Distributions to Noncontrolling Interest Holders and Stock Issued During Period Value Dividend Reinvestment Plan Sum of a) Equity impact of aggregate cash, stock, and paid-in-kind dividends declared for all securities (common shares, preferred shares, etc.) during the period, b) Decrease in noncontrolling interest balance from payment of dividends or other distributions by the non-wholly owned subsidiary or partially owned entity, included in the consolidation of the parent entity, to the noncontrolling interest holders, and c) Value of stock issued during the period from a dividend reinvestment plan (DRP). A dividend reinvestment plan allows the holder of the stock to reinvest dividends paid to them by the entity on new issues of stock by the entity. 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