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 Document Fiscal Year Focus Document Fiscal Period Focus Entity Common Stock, Shares Outstanding Consolidated Balance Sheets [Abstract] ASSETS Rental Property [Abstract] Rental Property [Abstract] Rental property Land And Leasehold Land And Leasehold Land and leasehold interests Buildings and improvements Tenant improvements Furniture, fixtures and equipment Gross investment in rental property Gross investment in rental property Less - accumulated depreciation and amortization Less - accumulated depreciation and amortization Less - Accumulated depreciation Net book value Total investment in rental property Real Estate Held-for-sale Aggregate carrying value Rental property held for sale, net Rental property held for sale, net Net Investment In Rental Property And Rental Property Held For Sale Net Investment In Rental Property And Rental Property Held For Sale Net investment in rental property Cash and cash equivalents, beginning of period Cash and cash equivalents Restricted Cash And Cash Equivalents Total restricted cash Restricted cash Carrying Amount Total investments in unconsolidated joint ventures Carrying Value Investments in unconsolidated joint ventures Unbilled rents receivable, net Other Assets Total deferred charges, goodwill and other assets, net Deferred charges, goodwill and other assets, net Accounts Receivable Net Accounts receivable, net of allowance for doubtful accounts of $329 and $1,138 Total assets Total assets LIABILITIES AND EQUITY Senior Notes Senior unsecured notes, net Revolving credit facility Unsecured revolving credit facility and term loans Amount outstanding Outstanding borrowings under the facility Secured Debt Mortgages, loans payable and other obligations, net Dividends and distributions payable Accounts payable, accrued expenses and other liabilities 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 Total liabilities Total liabilities Commitments And Contingencies 2009 Commitments and contingencies Redeemable Noncontrolling Interest, Equity, Fair Value Redeemable noncontrolling interests as of June 30, 2018 Balance January 1, 2018 Redeemable noncontrolling interests Equity: Stockholders' Equity Attributable to Parent [Abstract] Mack-Cali Realty stockholders' equity: Common stock value Common stock, $0.01 par value, 190,000,000 shares authorized, 90,286,268 and 89,914,113 shares outstanding Additional Paid In Capital Additional paid-in capital General Partners' Capital Account General Partner, 90,286,268 and 89,914,113 common units outstanding Limited Partners' Capital Account Limited partners, 10,211,079 and 10,438,855 common units outstanding Retained Earnings Accumulated Deficit Dividends in excess of net earnings Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated other comprehensive income (loss) Stockholders' Equity Attributable to Parent Total Mack-Cali Realty Corporation stockholders' equity Partners' Capital Total Mack-Cali Realty, L.P. partners' capital Noncontrolling Interest Items [Abstract] Noncontrolling interests in subsidiaries: Operating Partnership Minority Interest In Joint Ventures Consolidated joint ventures Total noncontrolling interests in subsidiaries Balance, value Balance, value Total noncontrolling interests in subsidiaries Total equity Balance, value Balance, value Total equity Partners' Capital Attributable to Noncontrolling Interest Noncontrolling interests in consolidated joint ventures Partners' Capital, Including Portion Attributable to Noncontrolling Interest Balance, value Balance, value Total equity Liabilities And Stockholders Equity Total liabilities and equity Allowance for doubtful accounts receivable Allowance for doubtful accounts receivable Common stock, par value per share Common stock, shares authorized Common Stock Shares Outstanding Common stock, shares outstanding General Partners' Capital Account, Units Outstanding General partner common units outstanding Limited Partners' Capital Account, Units Outstanding Limited partner common units outstanding Consolidated Statements Of Operations [Abstract] Revenues Abstract REVENUES Revenues Total revenues Total revenues EXPENSES Real estate taxes Utilities Operating services The aggregate costs including administrative paperwork, real estate brokerage, title, and property management operations. Costs Of Real Estate Services Real estate services expenses General and administrative Depreciation and amortization Depreciation and amortization Costs and Expenses Total expenses Operating income Operating income OTHER (EXPENSE) INCOME Interest expense Interest expense Investment Income (Loss), Nonoperating Investment Income (Loss), Nonoperating Interest and other investment income (loss) Equity in earnings (loss) of unconsolidated joint ventures Equity in (earnings) loss of unconsolidated joint ventures Equity in earnings (loss) of unconsolidated joint ventures Company's equity in earnings of unconsolidated joint ventures Realized gains on disposition of rental property Realized gains (losses) and unrealized losses on disposition of rental property, net Gain (Loss) on Sale of Investments Gain on sale of investments in unconsolidated joint ventures Gain on sale of investment in unconsolidated joint venture Extinguishment of Debt, Gain (Loss), Net of Tax Loss from extinguishment of debt, net Nonoperating Income Expense Including Equity Method Investments Nonoperating Income Expense Including Equity Method Investments Total other income (expense) Net income Net income (loss) Net income (loss) Noncontrolling interest in consolidated joint ventures Add (deduct): Noncontrolling interest in consolidated joint ventures Noncontrolling interest in consolidated joint ventures Noncontrolling interest in operating partnership Noncontrolling interest in Operating Partnership Add (deduct): Noncontrolling interest in Operating Partnership Add (deduct): Noncontrolling interest in Operating Partnership Net Income (Loss) Attributable to Redeemable Noncontrolling Interest Redeemable noncontrolling interest Income Attributed to Noncontrolling Interests Net income (loss) available to common shareholders Net income (loss) available to common shareholders Basic earnings per common share: Earnings Per Share, Basic Net income (loss) available to common shareholders Diluted earnings per common share: Earnings Per Share Diluted Net income (loss) available to common shareholders Basic weighted average shares outstanding Basic EPS shares Weighted average common shares Diluted weighted average shares outstanding Weighted average common shares Diluted EPS Shares Weighted Average Limited Partnership Units Outstanding, Basic Basic EPS units Basic weighted average units outstanding Weighted average common units Weighted Average Limited Partnership Units Outstanding, Diluted Diluted EPU Units Diluted weighted average units outstanding Weighted average common unit Consolidated Statements Of Comprehensive Income (Loss) [Abstract] Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Other comprehensive income: Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax Net unrealized gain (loss) on derivative instruments for interest rate swaps Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Comprehensive income (loss) Comprehensive Income (Loss), Net Of Tax Attributable To Noncontrolling Interest Joint Venture Partners, Nonredeemable Comprehensive Income (Loss), Net Of Tax Attributable To Noncontrolling Interest Joint Venture Partners, Nonredeemable Comprehensive (income) loss attributable to noncontrolling interest in consolidated joint ventures Comprehensive Income Loss Net Of Tax Attributable To Redeemable Noncontrolling Interest Comprehensive Income Loss Net Of Tax Attributable To Redeemable Noncontrolling Interest Comprehensive (income) loss attributable to redeemable noncontrolling interest Comprehensive Income (Loss), Net Of Tax Attributable To, Noncontrolling Interest Operating Partnerships, Nonredeemable Comprehensive Income (Loss), Net Of Tax Attributable To, Noncontrolling Interest Operating Partnerships, Nonredeemable Comprehensive (income) loss attributable to noncontrolling interest in Operating Partnership Comprehensive Income (Loss), Net of Tax, Attributable to Parent Comprehensive income (loss) attributable to common shareholders Consolidated Statement Of Changes In Equity [Abstract] 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] Retained Earnings [Member] Dividends In Excess Of Net Earnings [Member] Noncontrolling Interest [Member] Noncontrolling Interests In Subsidiaries [Member] Shares, Issued Balance, shares Balance, shares Partners' Capital Account, Units Balance, units Balance, units Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest Net income Common stock dividends Common stock dividends Common unit distributions Common unit distributions Unit distributions Redeemable Noncontrolling Interest Redemption Value Adjustment Redeemable Noncontrolling Interest Redemption Value Adjustment Redemption Value Adjustment Redeemable noncontrolling interest Noncontrolling Interest, Period Increase (Decrease) Increase in noncontrolling interest Minority Interest, Increase (Decrease) From Redemptions Minority Interest, Increase (Decrease) From Redemptions Redemption of common units for common stock, value Stock Issued During Period, Shares, Conversion of Units Redemption of common units for shares of common stock, shares Adjustments to Additional Paid in Capital, Dividends in Excess of Retained Earnings Shares issued under Dividend Reinvestment and Stock Purchase Plan, value Stock Dividends, Shares Shares issued under Dividend Reinvestment and Stock Purchase Plan, shares Stock Issued During Period, Value, Restricted Stock Award, Gross Directors' deferred compensation plan, value Stock Issued During Period, Shares, Restricted Stock Award, Gross Directors' deferred compensation plan, shares Adjustments To Additional Paid In Capital Sharebased Compensation Value Adjustments To Additional Paid In Capital Sharebased Compensation Value Stock compensation, value Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures Stock compensation, shares Stock Issued During Period, Value, Share-based Compensation, Forfeited Cancellation of restricted shares, value Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period Cancellation of restricted shares, shares Shares forfeited and cancelled Other Comprehensive Income (Loss), Net of Tax Other comprehensive income (loss) Noncontrolling Interest, Increase (Decrease) from Subsidiary Equity Issuance Noncontrolling Interest, Increase (Decrease) from Subsidiary Equity Issuance Rebalancing of ownership percentage between parent and subsidiaries Consolidated Statements Of Cash Flows [Abstract] CASH FLOWS FROM OPERATING ACTIVITIES Adjustments to reconcile net income (loss) to net cash provided by Operating activities: Depreciation and amortization, including related intangible assets Amortization Of Deferred Stock Units Amortization Of Deferred Stock Units Amortization of directors deferred compensation stock units Stock compensation Amortization of stock compensation Amortization of deferred financing costs Amortization Of Debt Discount And Mark-To-Market Amortization Of Debt Discount And Mark-To-Market Amortization of debt discount and mark-to-market Write off of Deferred Debt Issuance Cost Write-off of unamortized deferred financing costs Write off of unamortized deferred financing costs related to early extinguishment Equity Method Investment Dividends Or Distributions Distributions of cumulative earnings from unconsolidated joint ventures Realized Gains Loss On Disposition Of Assets, Including Discontinued Operations Realized Gains Loss On Disposition Of Assets, Including Discontinued Operations Realized (gains) losses and unrealized losses on disposition of rental property, net Gains (Losses) on Extinguishment of Debt Loss from extinguishment of debt Loss from extinguishment of debt, net Changes in operating assets and liabilities: Increase Decrease In Unbilled Rent Receivables Increase Decrease In Unbilled Rent Receivables Increase in unbilled rents receivable, net Increase in deferred charges and other assets, net Increase in deferred charges, goodwill and other assets (Increase) decrease in accounts receivable, net Decrease in accounts receivable, net Increase (decrease) in accounts payable, accrued expenses and other liabilities Increase (decrease) in accounts payable, accrued expenses and other liabilities 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 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 Payments to Acquire Businesses, Net of Cash Acquired Rental property acquisitions and related intangibles Payments to Acquire and Develop Real Estate Rental property additions and improvements Purchase price of property Payments to Develop Real Estate Assets Development of rental property and other related costs Net Sales Proceeds Proceeds from the sales of rental property Proceeds from Divestiture of Interest in Joint Venture Proceeds from the sale of investments in unconsolidated joint ventures Payments to Acquire Notes Receivable Investments in notes receivable Proceeds from Collection of Loans Receivable Repayment of notes receivable Investment in unconsolidated joint ventures Investment in unconsolidated joint ventures 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 Proceeds From Investment Receivable Proceeds From Investment Receivable Proceeds from investment receivable Net cash used in investing activities Net cash provided by (used in) investing activities CASH FLOW FROM FINANCING ACTIVITIES Borrowings from revolving credit facility Repayment of revolving credit facility and money market loans Repayment of revolving credit facility Payment for borrowings Proceeds From Unsecured Term Loan Proceeds From Unsecured Term Loan Borrowings from unsecured term loan Proceeds from Issuance of Secured Debt Proceeds from mortgages and loans payable Repayment of mortgages, loans payable and other obligations Repayment of mortgages, loans payable and other obligations Payments To Acquire Minority Interest Payments To Acquire Minority Interest Acquisition of noncontrolling interests Proceeds From Issuance Of Redeemable Noncontrolling Interests Proceeds From Issuance Of Redeemable Noncontrolling Interests Issuance of redeemable noncontrolling interests, net Payment of financing costs Payment of financing costs Proceeds from (Payments to) Noncontrolling Interests (Distribution to) contributions from noncontrolling interests Payment of dividends and distributions Payments of dividends and distributions Net cash provided used in financing activities Net cash (used in) provided by financing activities Net (decrease) increase in cash and cash equivalents Net decrease in cash and cash equivalents Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash, cash equivalents and restricted cash, end of period Cash, cash equivalents and restricted cash, beginning of period Organization And Basis Of Presentation [Abstract] Organization And Basis Of Presentation [Table] Organization And Basis Of Presentation [Table] Organization And Basis Of Presentation [Line Items] Organization And Basis Of Presentation [Line Items] Organization Consolidation And Presentation Of Financial Statements Disclosure TextBlock Organization And Basis Of Presentation Significant Accounting Policies [Abstract] Significant Accounting Policies [Table] Significant Accounting Policies [Table] Significant Accounting Policies [Line Items] Significant Accounting Policies [Line Items] Significant Accounting Policies Textblock Significant Accounting Policies Recent Transactions [Abstract] Recent Transactions [Abstract] Recent Transactions [Table] Recent Transactions [Table] Recent Transactions [Line Items] Recent Transactions [Line Items] Recent Transactions [Text Block] Recent Transactions [Text Block] Recent Transactions Investments In Unconsolidated Joint Ventures [Abstract] Investments In Unconsolidated Joint Ventures [Table] Investments In Unconsolidated Joint Ventures [Table] Investments In Unconsolidated Joint Ventures [Line Items] Investments In Unconsolidated Joint Ventures [Line Items] Equity Method Investments Disclosure TextBlock Investments In Unconsolidated Joint Ventures Deferred Charges, Goodwill And Other Assets, Net [Abstract]