Document and Entity Information [Abstract] Document And Entity Information [Abstract] Statement [Table] Statement [Line Items] Entity Registrant Name Document Type Amendment Flag Document Period End Date Entity Central Index Key Current Fiscal Year End Date Entity Filer Category Entity Common Stock, Shares Outstanding Document Fiscal Year Focus Document Fiscal Period Focus Consolidated Balance Sheets [Abstract] ASSETS Land and leasehold interests Buildings and improvements Investment Building and Building Improvements, Total Tenant improvements Furniture, fixtures and equipment Furniture, fixtures and equipment Gross investment in rental property Rental property, net Gross investment in rental property Less - accumulated depreciation and amortization Less - accumulated depreciation and amortization Less - accumulated depreciation and amortization Less - accumulated depreciation and amortization Net investment in rental property Net investment in rental property Properties aggregate net book value Cash and cash equivalents, beginning of period Cash and cash equivalents, end of period Cash and cash equivalents, beginning of period Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value, Total Investments In Affiliates Subsidiaries Associates And Joint Ventures Company's investment in unconsolidated joint ventures, net Investment in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures, Total Investments in unconsolidated joint ventures Unbilled rents receivable, net Deferred charges and other assets, net Other assets Total deferred charges and other assets, net Restricted Cash And Cash Equivalents Restricted cash Accounts Receivable Net Accounts receivable, net of allowance for doubtful accounts of $2,790 and $2,036 Accounts receivable, net of allowance for doubtful accounts of $2,905 and $2,319 Accounts receivable, net of allowance for doubtful accounts of $2,575 and $2,790 Total assets Total assets LIABILITIES AND EQUITY Unsecured Debt Senior unsecured notes Unsecured Debt, Total Revolving credit facility Long-term Line of Credit, Total Outstanding borrowings under the facility Secured Debt Mortgages, loans payable and other obligations Secured Debt, Total Mortgage loan Dividends and distributions payable Accounts payable, accrued expenses and other liabilities Accounts Payable and Accrued Liabilities, Total Amount at the balance sheet date including both: (a) rents and other amounts paid in advance by tenants and clients; and (b) security deposits paid in advance to protect the provider of a service, such as a lessor, against damage or nonpayment by the tenant (lessee) during the term of the agreement. Such damages may include physical damage to the property, theft of property, and other contractual breaches. Rents received in advance and security deposits Accrued interest payable Accrued interest payable Total liabilities Total liabilities and partners'/members' capital (deficit) Total liabilities Commitments And Contingencies 2009 Commitments and contingencies Equity: Preferred stock, $0.01 par value, 5,000,000 shares authorized, 10,000 and 10,000 shares outstanding, at liquidation preference Preferred Stock, Value, Issued, Ending Balance Preferred Stock, Value, Issued, Beginning Balance Preferred stock issued Preferred Stock, Value, Issued, Total Series C preferred stock redemption value Common stock value Common stock, $0.01 par value, 190,000,000 shares authorized, 79,398,646 and 78,969,752 shares outstanding Common stock, $0.01 par value, 190,000,000 shares authorized, 79,398,646 and 78,969,752 shares outstanding Common stock, $0.01 par value, 190,000,000 shares authorized, 79,398,646 and 78,969,752 shares outstanding Common stock, $0.01 par value, 190,000,000 shares authorized, 79,398,646 and 78,969,752 shares outstanding Common stock, $0.01 par value, 190,000,000 shares authorized, 87,141,716 and 79,605,474 shares outstanding Additional Paid In Capital Additional Paid in Capital, Ending Balance Additional Paid in Capital, Beginning Balance Additional paid-in capital Additional Paid in Capital, Total Retained Earnings Accumulated Deficit Retained Earnings (Accumulated Deficit), Ending Balance Retained Earnings (Accumulated Deficit), Beginning Balance Dividends in excess of net earnings Dividends in excess of net earnings Stockholders' Equity Attributable to Parent Stockholders' Equity Attributable to Parent, Ending Balance Stockholders' Equity Attributable to Parent, Beginning Balance Total Mack-Cali Realty Corporation stockholders' equity Noncontrolling Interest Items [Abstract] Noncontrolling interests in subsidiaries: Operating Partnership Preferred unit in operating partnership Operating patnership acquired Minority Interest In Joint Ventures Consolidated joint ventures Consolidated joint ventures Noncontrolling interests in consolidated joint ventures Total noncontrolling interests in subsidiaries Balance at September 30, 2010 Balance at January 1, 2010 Total noncontrolling interests in subsidiaries Total equity Balance, value Balance, value Total equity Liabilities And Stockholders Equity Total liabilities and equity Total liabilities and equity Allowance for doubtful accounts receivable Allowance for doubtful accounts Preferred stock, par or stated value per share Preferred stock, par value per share Preferred stock, shares authorized Preferred stock, shares outstanding Preferred Stock, Shares Outstanding, Ending Balance Preferred Stock, Shares Outstanding, Beginning Balance Preferred stock, shares outstanding at liquidation preference Preferred shares Common stock, par value per share Common stock, shares authorized Common Stock Shares Outstanding Common Stock, Shares, Outstanding, Ending Balance Common Stock, Shares, Outstanding, Beginning Balance Common stock, shares outstanding Common shares / units Consolidated Statements Of Operations [Abstract] REVENUES Base rents Operating Leases, Income Statement, Lease Revenue, Total Escalations and recoveries from tenants Construction services Other Real Estate Revenue Real estate services Other income Operating and other Operating and other Other income Real Estate Revenue, Net Total revenues Total revenues EXPENSES Real estate taxes Utilities Operating services Operating Costs and Expenses, Total Direct construction costs General and administrative General and Administrative Expense, Total Depreciation and amortization Depreciation and amortization Depreciation and amortization Costs and Expenses Total expenses Operating income Operating income OTHER (EXPENSE) INCOME Interest expense Interest expense Interest Expense, Total Interest and other investment income Investment Income, Interest and Dividend, Total Equity in earnings (loss) of unconsolidated joint ventures Equity in earnings of unconsolidated joint venture, net Company's equity in earnings (loss) of unconsolidated joint ventures Income (Loss) from Equity Method Investments, Total Nonoperating Income (Expense) Total other (expense) income Income from continuing operations Income from continuing operations Discontinued Operations And Disposal Groups Abstract Discontinued operations: Income (loss) from discontinued operations for diluted earnings per share Discontinued Operation, Income (Loss) from Discontinued Operation During Phase-out Period, Net of Tax Income from discontinued operations before gains (losses) and unrealized losses on disposition of rental property Income from discontinued operations before gains (losses) and unrealized losses on disposition of rental property Income (loss) from discontinued operations Gain (Loss) on Disposition of Assets Realized gains (losses) and unrealized losses on disposition of rental property, net Gain (Loss) on Disposition of Assets, Total Realized gains (losses) and unrealized losses on disposition of rental property, net Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest Total discontinued operations, net Total discontinued operations, net Income (loss) from discontinued operations for diluted earnings per share Net income Net income Net income Noncontrolling interest in consolidated joint ventures Noncontrolling interest in consolidated joint ventures Equity in (earnings) loss of unconsolidated joint venture, net Add: Noncontrolling interest in consolidated joint ventures Noncontrolling interest in operating partnership Noncontrolling interest in Operating Partnership Noncontrolling interest in operating partnership Add: Noncontrolling interest in operating partnership Deduct: Noncontrolling interest in Operating Partnership Amount of net income (loss) for the period allocated to noncontrolling partners in discontinued operations included in the entity's consolidated financial statements. Noncontrolling interest in discontinued operations Noncontrolling interest in discontinued operations Dividends Preferred Stock Preferred stock dividends Preferred stock dividends Preferred stock dividends Dividends, Preferred Stock, Total Deduct: Preferred stock dividends Net Income Loss Net income available to common shareholders Net income available to common shareholders Net operating income Basic earnings per common share: Income Loss From Continuing Operations Per Basic Share Income from continuing operations Income from continuing operations available to common shareholders Income from continuing operations available to common shareholders Income (Loss) from Discontinued Operations, Net of Tax, Per Basic Share Discontinued operations Discontinued operations Income (Loss) from Discontinued Operations, Net of Tax, Per Outstanding Share, Total Income (loss) from discontinued operations available to common shareholders Net income available to common shareholders Net income available to common shareholders Net income available to common shareholders Diluted earnings per common share: Income Loss From Continuing Operations Per Diluted Share Income from continuing operations Income from continuing operations available to common shareholders Income from continuing operations available to common shareholders Income (Loss) from Discontinued Operations, Net of Tax, Per Diluted Share Discontinued operations Income (Loss) from Discontinued Operations, Net of Tax, Per Diluted Share, Total Income (loss) from discontinued operations available to common shareholders Earnings Per Share Diluted Net income available to common unitholders Net income available to common shareholders Basic weighted average shares outstanding Basic EPS shares Basic weighted average shares outstanding Weighted average common shares Diluted weighted average shares outstanding Weighted average common shares Diluted EPS Shares Diluted EPS Shares Consolidated Statement Of Changes In Equity [Abstract] Shares, Issued Balance, shares Balance, shares Common stock dividends Common stock dividends Dividends, Common Stock, Total Common unit distributions Common unit distributions Common stock offering Common stock offering, value Common stock offering, shares Increase in noncontrolling interest Decrease in noncontrolling interest Decrease in noncontrolling interest Noncontrolling Interest, Period Increase (Decrease), Total Redemption of common units for common stock, value Redemption of common units for common stock, value Redemption of common units for common stock, shares Redemption of common units for shares of Common Stock Redemption of common units for shares of common stock Shares issued under Dividend Reinvestment and Stock Purchase Plan, value Shares issued under Dividend Reinvestment and Stock Purchase Plan, shares Stock options exercised, value Stock options exercised, shares Share Under Options - Exercised Share Under Options - Exercised Stock Compensation, value Stock compensation Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition, Total Accrued Redemption Of Preferred Stock Accrued Redemption Of Preferred Stock Accrued redemption of preferred stock Accrued redemption of preferred stock Rebalancing of ownership percent between parent and subsidiaries Decrease in additional paid-in capital Statement, Equity Components [Axis] Equity Component [Domain] Preferred Stock [Member] Common Stock [Member] Additional Paid-In Capital [Member] Dividends In Excess Of Net Earnings [Member] Noncontrolling Interests In Subsidiaries [Member] Consolidated Statements Of Cash Flows [Abstract] CASH FLOWS FROM OPERATING ACTIVITIES Adjustments to reconcile net income to net cash provided by Operating activities: Depreciation and amortization, including related intangible assets Depreciation, Depletion and Amortization, Total Depreciation Amortization On Discontinued Operations Depreciation Amortization On Discontinued Operations Depreciation and amortization on discontinued operations Depreciation and amortization Depreciation and amortization on discontinued operations Stock compensation Amortization of stock compensation Amortization of stock compensation Amortization of deferred financing costs and debt discount Amortization of Financing Costs and Discounts, Total Gain (Loss) on Disposition of Property Realized gains on disposition of rental property (Realized gains) unrealized losses on disposition of rental property Gain on disposal of office property Gain (Loss) on Disposition of Property, Total Equity Method Investment Dividends Or Distributions Distributions of cumulative earnings from unconsolidated joint ventures Distributions of cumulative earnings from unconsolidated joint ventures Changes in operating assets and liabilities: Increase in unbilled rents receivable, net Increase in unbilled rents receivable, net Increase in deferred charges and other assets, net Increase in deferred charges and other assets, net (Increase) decrease in deferred charges and other assets, net (Increase) decrease in deferred charges and other assets, net Increase (Decrease) in Other Operating Assets, Total (Increase) decrease in accounts receivable, net Decrease (increase) in accounts receivable, net Increase (decrease) in accounts payable, accrued expenses and other liabilities Increase (decrease) in accounts payable, accrued expenses and other liabilities Decrease in accounts payable, accrued expenses and other liabilities Increase in accounts payable, accrued expenses and other liabilities Increase (Decrease) in Accounts Payable and Accrued Liabilities, Total The net change during the reporting period in the amount at the balance sheet date including both: (a) rents and other amounts paid in advance by tenants and clients; and (b) security deposits paid in advance to protect the provider of a service, such as a lessor, against damage or nonpayment by the tenant (lessee) during the term of the agreement Increase Decrease In Rents Received In Advance And Security Deposits (Decrease) increase in rents received in advance and security deposits Increase (decrease) in rents received in advance and security deposits Decrease in rents received in advance and security deposits Decrease in accrued interest payable Decrease in accrued interest payable Decrease in accrued interest payable Decrease in accrued interest payable (Decrease) increase in accrued interest payable Net cash provided by operating activities Net cash provided by operating activities CASH FLOWS FROM INVESTING ACTIVITIES Additions to rental property and related intangibles Additions to rental property and related intangibles Additions to rental property and related intangibles Additions to rental property and related intangibles Investment in unconsolidated joint ventures Investment in unconsolidated joint ventures Acquisition cost This item represents the amount of distributions in excess of net earnings, which represents a return of investment, received from unconsolidated joint ventures and subsidiaries; these investments are accounted for under the equity method of accounting. Distributions In Excess Of Cumulative Earnings From Jvs Distributions in excess of cumulative earnings from unconsolidated joint ventures Distributions in excess of cumulative earnings from unconsolidated joint ventures Increase Decrease In Restricted Cash (Increase) decrease in restricted cash (Increase) decrease in restricted cash (Increase) decrease in restricted cash Decrease (increase) in restricted cash Net cash used in investing activities Net cash used in investing activities CASH FLOW FROM FINANCING ACTIVITIES Borrowings from revolving credit facility Borrowings from revolving credit facility Unsecured credit facility Repayment of revolving credit facility and money market loans Repayment of revolving credit facility Repayments of senior unsecured notes Repayment of senior unsecured notes Proceeds from offering of Common Stock Proceeds from offering of common stock Proceeds from issuance of common stock Repayment of mortgages, loans payable and other obligations Repayment of mortgages, loans payable and other obligations Repayment of mortgages, loans payable Payment of financing costs Payment of financing costs Payments of Financing Costs, Total Proceeds from stock options exercised Payment of dividends and distributions Payment of dividends and distributions Payment of dividends and distributions Payment of dividends and distributions Net cash provided used in financing activities Net cash used in financing activities Net (decrease) increase in cash and cash equivalents Net decrease in cash and cash equivalents Organization And Basis Of Presentation [Abstract] Organization Consolidation And Presentation Of Financial Statements Disclosure TextBlock Organization And Basis Of Presentation Significant Accounting Policies [Abstract] Significant Accounting Policies Textblock Significant Accounting Policies Real Estate Transaction [Abstract] Real Estate Transactions Textblock Real Estate Transaction REAL ESTATE TRANSACTION Investments In Unconsolidated Joint Ventures [Abstract] Equity Method Investments Disclosure TextBlock Investments In Unconsolidated Joint Ventures Deferred Charges and Other Assets [Abstract] Deferred Charges And Other Assets [Abstract] Deferred Costs Capitalized Prepaid And Other Assets Disclosure TextBlock Deferred Charges And Other Assets Discontinued Operations [Abstract] Discontinued Operations [Abstract] Discontinued operations: Discontinued Operations Policy TextBlock Discontinued Operations DISCONTINUED OPERATIONS Senior Unsecured Notes Senior Unsecured Notes [Abstract] Description of an entity's senior unsecured notes Senior Unsecured Notes [Text Block] Senior Unsecured Notes SENIOR UNSECURED NOTES Unsecured Revolving Credit Facility [Abstract] Unsecured Revolving Credit Facility [Abstract] Schedule Of Line Of Credit Facilities TextBlock Unsecured Revolving Credit Facility Mortgages, Loans Payable and Other Obligations [Abstract] Mortgages, Loans Payable And Other Obligations [Abstract] Description of an entity's mortgages, loans payable and other obligations Mortgages And Notes Payable [Text Block] Mortgages, Loans Payable And Other Obligations MORTGAGES, LOANS PAYABLE AND OTHER OBLIGATIONS Employee Benefit 401(k) Plans [Abstract] Pension And Other Postretirement Benefits Disclosure TextBlock Employee Benefit 401(k) Plans EMPLOYEE BENEFIT 401(k) PLANS Disclosure Of Fair Value Of Financial Instruments [Abstract] Fair Value Disclosures TextBlock Disclosure Of Fair Value Of Financial Instruments Commitments And Contingencies [Abstract] Commitments and Contingencies Disclosure Textblock Commitments And Contingencies Tenant Leases [Abstract] Tenant Leases [Abstract] Leases Of Lessor Disclosure TextBlock Tenant Leases Mack-Cali Realty Corporation Stockholders' Equity [Abstract] Stockholders Equity Note Disclosure TextBlock Mack-Cali Realty Corporation Stockholders' Equity Noncontrolling Interests in Subsidiaries [Abstract] Noncontrolling Interests In Subsidiaries [Abstract] Minority Interest Disclosure TextBlock Noncontrolling Interests In Subsidiaries NONCONTROLLING INTERESTS IN SUBSIDIARIES Segment Reporting [Abstract] Segment Reporting Disclosure Textblock Segment Reporting Property, Plant and Equipment, Policy [Text Block] Estimated Useful Lives of Assets Rental Property Real Estate Held for Development and Sale, Policy Rental Property Held For Sale And Discontinued Operations Equity Method Investments, Policy Investments In Unconsolidated Joint Ventures Cash and Cash Equivalents, Policy [Text Block] Cash And Cash Equivalents Marketable Securities, Policy Marketable Securities Disclosure of entity's accounting policy for costs incurred in connection with obtaining finance. Deferred Financing Costs Policy Text Block Deferred Financing Costs