Veris Residential (VRE) 10-K 21 Feb 18 2017 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Feb. 16, 2018	Jun. 30, 2017
Entity Registrant Name	MACK CALI REALTY CORP
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Entity Central Index Key	924,901
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Entity Current Reporting Status	Yes
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Public Float			$ 2,424,863,956
Entity Common Stock, Shares Outstanding		90,139,823
Mack-Cali Realty LP [Member]
Entity Registrant Name	MACK CALI REALTY LP
Entity Central Index Key	1,067,063
Entity Filer Category	Large Accelerated Filer

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Rental property
Land and leasehold interests	$ 786,789	$ 661,335
Buildings and improvements	3,955,122	3,758,210
Tenant improvements	330,686	364,092
Furniture, fixtures and equipment	30,247	21,230
Gross investment in rental property	5,102,844	4,804,867
Less - accumulated depreciation and amortization	(1,087,083)	(1,332,073)
Total investment in rental property	4,015,761	3,472,794
Rental property held for sale, net	171,578	39,743
Net investment in rental property	4,187,339	3,512,537
Cash and cash equivalents	28,180	31,611
Investments in unconsolidated joint ventures	252,626	320,047
Unbilled rents receivable, net	100,842	101,052
Deferred charges, goodwill and other assets, net	342,320	267,950
Restricted cash	39,792	53,952
Accounts receivable, net of allowance for doubtful accounts of $1,138 and $1,335	6,786	9,617
Total assets	4,957,885	4,296,766
LIABILITIES AND EQUITY
Senior unsecured notes, net	569,145	817,355
Unsecured revolving credit facility and term loans	822,288	634,069
Mortgages, loans payable and other obligations, net	1,418,135	888,585
Dividends and distributions payable	21,158	15,327
Accounts payable, accrued expenses and other liabilities	192,716	159,874
Rents received in advance and security deposits	43,993	46,442
Accrued interest payable	9,519	8,427
Total liabilities	3,076,954	2,570,079
Commitments and contingencies
Redeemable noncontrolling interests	212,208
Mack-Cali Realty stockholders' equity:
Common stock, $0.01 par value, 190,000,000 shares authorized, 89,914,113 and 89,696,713 shares outstanding	899	897
Additional paid-in capital	2,565,136	2,576,473
Dividends in excess of net earnings	(1,096,429)	(1,052,184)
Accumulated other comprehensive income (loss)	6,689	1,985
Total Mack-Cali Realty Corporation stockholders' equity	1,476,295	1,527,171
Noncontrolling interests in subsidiaries:
Operating Partnership	171,395	178,570
Consolidated joint ventures	21,033	20,946
Total noncontrolling interests in subsidiaries	192,428	199,516
Total equity	1,668,723	1,726,687
Total liabilities and equity	4,957,885	4,296,766
Mack-Cali Realty LP [Member]
Rental property
Land and leasehold interests	786,789	661,335
Buildings and improvements	3,955,122	3,758,210
Tenant improvements	330,686	364,092
Furniture, fixtures and equipment	30,247	21,230
Gross investment in rental property	5,102,844	4,804,867
Less - accumulated depreciation and amortization	(1,087,083)	(1,332,073)
Total investment in rental property	4,015,761	3,472,794
Rental property held for sale, net	171,578	39,743
Net investment in rental property	4,187,339	3,512,537
Cash and cash equivalents	28,180	31,611
Investments in unconsolidated joint ventures	252,626	320,047
Unbilled rents receivable, net	100,842	101,052
Deferred charges, goodwill and other assets, net	342,320	267,950
Restricted cash	39,792	53,952
Accounts receivable, net of allowance for doubtful accounts of $1,138 and $1,335	6,786	9,617
Total assets	4,957,885	4,296,766
LIABILITIES AND EQUITY
Senior unsecured notes, net	569,145	817,355
Unsecured revolving credit facility and term loans	822,288	634,069
Mortgages, loans payable and other obligations, net	1,418,135	888,585
Dividends and distributions payable	21,158	15,327
Accounts payable, accrued expenses and other liabilities	192,716	159,874
Rents received in advance and security deposits	43,993	46,442
Accrued interest payable	9,519	8,427
Total liabilities	3,076,954	2,570,079
Commitments and contingencies
Redeemable noncontrolling interests	212,208
Mack-Cali Realty stockholders' equity:
General Partner, 89,914,113 and 89,696,713 common units outstanding	1,407,366	1,467,569
Limited partners, 10,438,855 and 10,488,105 common units outstanding	233,635	236,187
Accumulated other comprehensive income (loss)	6,689	1,985
Total Mack-Cali Realty, L.P. partners' capital	1,647,690	1,705,741
Noncontrolling interests in subsidiaries:
Noncontrolling interests in consolidated joint ventures	21,033	20,946
Total equity	1,668,723	1,726,687
Total liabilities and equity	$ 4,957,885	$ 4,296,766

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Allowance for doubtful accounts receivable	$ 1,138	$ 1,335
Common stock, par value per share	$ 0.01	$ 0.01
Common stock, shares authorized	190,000,000	190,000,000
Common stock, shares outstanding	89,914,113	89,696,713
Mack-Cali Realty LP [Member]
Allowance for doubtful accounts receivable	$ 1,138	$ 1,335
General partner common units outstanding	89,914,113	89,696,713
Limited partner common units outstanding	10,438,855	10,488,105

Consolidated Statements Of Oper

Consolidated Statements Of Operations - USD ($) shares in Thousands, $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
REVENUES
Base rents										$ 501,334	$ 506,877	$ 487,041
Escalations and recoveries from tenants										58,767	60,505	62,481
Real estate services										23,129	26,589	29,620
Parking income										20,270	13,630	11,124
Other income										12,700	5,797	4,617
Total revenues		$ 143,529	$ 160,018	$ 162,766	$ 149,887	$ 153,731	$ 157,517	$ 149,227	$ 152,923	616,200	613,398	594,883
EXPENSES
Real estate taxes										81,364	87,379	82,688
Utilities										42,598	49,624	55,965
Operating services										107,379	103,954	107,951
Real estate services expenses										23,394	26,260	25,583
General and administrative										50,949	51,979	49,147
Acquisition-related costs											2,880	1,560
Depreciation and amortization										205,169	186,684	170,402
Impairments												197,919
Total expenses										510,853	508,760	691,215
Operating income (loss)										105,347	104,638	(96,332)
OTHER (EXPENSE) INCOME
Interest expense										(93,388)	(94,889)	(103,051)
Interest and other investment income (loss)										2,766	1,614	794
Equity in earnings (loss) of unconsolidated joint ventures	[1]									(6,081)	18,788	(3,172)
Gain on change of control of interests											15,347
Realized gains (losses) and unrealized losses on disposition of rental property, net										2,364	109,666	53,261
Gain on sale of investment in unconsolidated joint venture										23,131	5,670	6,448
Loss from extinguishment of debt, net										(421)	(30,540)
Total other income (expense)										(71,629)	25,656	(45,720)
Net income (loss)		5,411	44,703	(39,125)	22,729	16,764	(9,605)	54,366	68,769	33,718	130,294	(142,052)
Noncontrolling interest in consolidated joint ventures										1,018	651	1,044
Noncontrolling interest in Operating Partnership										(2,711)	(13,721)	15,256
Redeemable noncontrolling interest										(8,840)
Net income (loss) available to common shareholders		$ 2,582	$ 38,054	$ (37,330)	$ 19,879	$ 15,181	$ (8,541)	$ 48,393	$ 62,191	$ 23,185	$ 117,224	$ (125,752)
Basic earnings per common share:
Net income (loss) available to common shareholders		$ (0.01)	$ 0.39	$ (0.44)	$ 0.11	$ 0.17	$ (0.10)	$ 0.54	$ 0.69	$ 0.06	$ 1.31	$ (1.41)
Diluted earnings per common share:
Net income (loss) available to common shareholders		$ (0.01)	$ 0.39	$ (0.44)	$ 0.11	$ 0.17	$ (0.10)	$ 0.54	$ 0.69	$ 0.06	$ 1.30	$ (1.41)
Basic weighted average shares outstanding										90,005	89,746	89,291
Diluted weighted average shares outstanding										100,703	100,498	100,222
Mack-Cali Realty LP [Member]
REVENUES
Base rents										$ 501,334	$ 506,877	$ 487,041
Escalations and recoveries from tenants										58,767	60,505	62,481
Real estate services										23,129	26,589	29,620
Parking income										20,270	13,630	11,124
Other income										12,700	5,797	4,617
Total revenues		$ 143,529	$ 160,018	$ 162,766	$ 149,887	$ 153,731	$ 157,517	$ 149,227	$ 152,923	616,200	613,398	594,883
EXPENSES
Real estate taxes										81,364	87,379	82,688
Utilities										42,598	49,624	55,965
Operating services										107,379	103,954	107,951
Real estate services expenses										23,394	26,260	25,583
General and administrative										50,949	51,979	49,147
Acquisition-related costs											2,880	1,560
Depreciation and amortization										205,169	186,684	170,402
Impairments												197,919
Total expenses										510,853	508,760	691,215
Operating income (loss)										105,347	104,638	(96,332)
OTHER (EXPENSE) INCOME
Interest expense										(93,388)	(94,889)	(103,051)
Interest and other investment income (loss)										2,766	1,614	794
Equity in earnings (loss) of unconsolidated joint ventures										(6,081)	18,788	(3,172)
Gain on change of control of interests											15,347
Realized gains (losses) and unrealized losses on disposition of rental property, net										2,364	109,666	53,261
Gain on sale of investment in unconsolidated joint venture										23,131	5,670	6,448
Loss from extinguishment of debt, net										(421)	(30,540)
Total other income (expense)										(71,629)	25,656	(45,720)
Net income (loss)		5,411	44,703	(39,125)	22,729	16,764	(9,605)	54,366	68,769	33,718	130,294	(142,052)
Noncontrolling interest in consolidated joint ventures										1,018	651	1,044
Redeemable noncontrolling interest										(8,840)
Net income (loss) available to common shareholders		$ 2,881	$ 42,467	$ (41,626)	$ 22,174	$ 16,955	$ (9,540)	$ 54,055	$ 69,475	$ 25,896	$ 130,945	$ (141,008)
Basic earnings per common share:
Net income (loss) available to common shareholders		$ (0.01)	$ 0.39	$ (0.44)	$ 0.11	$ 0.17	$ (0.10)	$ 0.54	$ 0.69	$ 0.06	$ 1.31	$ (1.41)
Diluted earnings per common share:
Net income (loss) available to common shareholders		$ (0.01)	$ 0.39	$ (0.44)	$ 0.11	$ 0.17	$ (0.10)	$ 0.54	$ 0.69	$ 0.06	$ 1.30	$ (1.41)
Basic weighted average units outstanding										100,410	100,245	100,222
Diluted weighted average units outstanding										100,703	100,498	100,222
[1]	Amounts are net of amortization of basis differences of $792, $436 and $336 for the years ended December 31, 2017, 2016 and 2015, respectively.

Consolidated Statements Of Comp

Consolidated Statements Of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net income (loss)	$ 33,718	$ 130,294	$ (142,052)
Other comprehensive income (loss):
Net unrealized gain (loss) on derivative instruments for interest rate swaps	5,250	2,216
Comprehensive income (loss)	38,968	132,510	(142,052)
Comprehensive (income) loss attributable to noncontrolling interest in consolidated joint ventures	1,018	651	1,044
Comprehensive (income) loss attributable to redeemable noncontrolling interest	(8,840)
Comprehensive (income) loss attributable to noncontrolling interest in Operating Partnership	(3,257)	(13,952)	15,256
Comprehensive income (loss) attributable to common shareholders	27,889	119,209	(125,752)
Mack-Cali Realty LP [Member]
Net income (loss)	33,718	130,294	(142,052)
Other comprehensive income (loss):
Net unrealized gain (loss) on derivative instruments for interest rate swaps	5,250	2,216
Comprehensive income (loss)	38,968	132,510	(142,052)
Comprehensive (income) loss attributable to noncontrolling interest in consolidated joint ventures	1,018	651	1,044
Comprehensive (income) loss attributable to redeemable noncontrolling interest	(8,840)
Comprehensive income (loss) attributable to common shareholders	$ 31,146	$ 133,161	$ (141,008)

Consolidated Statement Of Chang

Consolidated Statement Of Changes In Equity - USD ($) shares in Thousands, $ in Thousands	Mack-Cali Realty LP [Member]General Partner Common Units [Member]	Mack-Cali Realty LP [Member]Limited Partner Common Units [Member]	Mack-Cali Realty LP [Member]General Partner Common Unitholders [Member]	Mack-Cali Realty LP [Member]Limited Partner Common Unitholders [Member]	Mack-Cali Realty LP [Member]Noncontrolling Interest In Consolidated Joint Ventures [Member]	Mack-Cali Realty LP [Member]Accumulated Other Comprehensive Income (Loss) [Member]	Mack-Cali Realty LP [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Dividends In Excess Of Net Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interests In Subsidiaries [Member]	Total
Balance, value at Dec. 31, 2014								$ 891	$ 2,560,183	$ (936,293)		$ 257,230	$ 1,882,011
Balance, shares at Dec. 31, 2014								89,077
Balance, value at Dec. 31, 2014			$ 1,568,098	$ 258,856	$ 55,057		$ 1,882,011
Balance, units at Dec. 31, 2014	89,077	11,084
Net income (loss)			(125,752)	(15,256)	(1,044)		(142,052)			(125,752)		(16,300)	(142,052)
Common stock dividends										(53,567)			(53,567)
Common unit distributions			(53,567)	(6,505)			(60,072)					(6,505)	(6,505)
Increase (Decrease) in noncontrolling interest in consolidated joint ventures					3,128		3,128					3,128	3,128
Redemption of common units for common stock, value			(9,947)	9,947				$ (6)	(9,941)			9,947
Redemption of common units for shares of common stock, shares	567	(567)						567
Shares issued under Dividend Reinvestment and Stock Purchase Plan, value			60				60		60				60
Shares issued under Dividend Reinvestment and Stock Purchase Plan, shares	3							3
Directors' deferred compensation plan, value			397				397		397				397
Stock compensation, value			2,277				2,277		2,277				2,277
Stock compensation, shares	46							46
Cancellation of restricted shares, value			(2,041)				(2,041)	$ (1)	(2,040)				(2,041)
Cancellation of restricted shares, shares	(109)							(109)
Rebalancing of ownership percentage between parent and subsidiaries									(426)			426
Balance, value at Dec. 31, 2015								$ 896	2,570,392	(1,115,612)		228,032	1,683,708
Balance, shares at Dec. 31, 2015								89,584
Balance, value at Dec. 31, 2015			1,399,419	227,148	57,141		1,683,708
Balance, units at Dec. 31, 2015	89,584	10,517
Net income (loss)			117,224	13,721	(651)		130,294			117,224		13,070	130,294
Common stock dividends										(53,796)			(53,796)
Common unit distributions			(53,796)	(6,619)			(60,415)					(6,619)	(6,619)
Increase (Decrease) in noncontrolling interest in consolidated joint ventures			414		(35,544)		(35,130)		414			(35,544)	(35,130)
Redemption of common units for common stock, value			(474)	474					(474)			474
Redemption of common units for shares of common stock, shares	29	(29)						29
Shares issued under Dividend Reinvestment and Stock Purchase Plan, value			71				71		71				71
Shares issued under Dividend Reinvestment and Stock Purchase Plan, shares	3							3
Directors' deferred compensation plan, value			372				372		372				372
Stock compensation, value			3,466	2,180			5,646	$ 1	3,465			2,180	5,646
Stock compensation, shares	85							85
Cancellation of restricted shares, value			(75)				(75)		(75)				(75)
Cancellation of restricted shares, shares	(4)							(4)
Other comprehensive income				231		$ 1,985	2,216				$ 1,985	231	2,216
Rebalancing of ownership percentage between parent and subsidiaries									1,360			(1,360)
Balance, value at Dec. 31, 2016								$ 897	2,576,473	(1,052,184)	1,985	199,516	1,726,687
Balance, shares at Dec. 31, 2016								89,697
Balance, value at Dec. 31, 2016			1,467,569	236,187	20,946	1,985	1,726,687
Balance, units at Dec. 31, 2016	89,697	10,488
Net income (loss)			23,185	2,711	7,822		33,718			23,185		10,533	33,718
Common stock dividends										(67,430)			(67,430)
Common unit distributions			(67,430)	(8,629)			(76,059)					(8,629)	(8,629)
Issuance of limited partner common units, value				2,793			2,793					2,793	2,793
Issuance of limited partner common units, shares		99
Redeemable noncontrolling interest			(17,951)	(2,074)	(8,840)		(28,865)		(17,951)			(10,914)	(28,865)
Increase (Decrease) in noncontrolling interest in consolidated joint ventures			(3,756)		1,105		(2,651)		(3,756)			1,105	(2,651)
Redemption of common units for common stock, value			(2,531)	2,531				$ (1)	(2,530)			2,531
Redemption of common units for shares of common stock, shares	149	(149)						149
Shares issued under Dividend Reinvestment and Stock Purchase Plan, value			67				67		67				67
Shares issued under Dividend Reinvestment and Stock Purchase Plan, shares	2							2
Directors' deferred compensation plan, value			482				482		482				482
Stock compensation, value			2,815	4,632			7,447	$ 1	2,814			4,632	7,447
Stock compensation, shares	70							70
Cancellation of restricted shares, value			(146)				(146)		(146)				(146)
Cancellation of restricted shares, shares	(4)							(4)
Other comprehensive income				546		4,704	5,250				4,704	546	5,250
Rebalancing of ownership percentage between parent and subsidiaries									4,623			(4,623)
Balance, value at Dec. 31, 2017								$ 899	$ 2,565,136	$ (1,096,429)	$ 6,689	$ 192,428	$ 1,668,723
Balance, shares at Dec. 31, 2017								89,914
Balance, value at Dec. 31, 2017			$ 1,407,366	$ 233,635	$ 21,033	$ 6,689	$ 1,668,723
Balance, units at Dec. 31, 2017	89,914	10,438

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)		$ 33,718	$ 130,294	$ (142,052)
Adjustments to reconcile net income to net cash provided by Operating activities:
Depreciation and amortization, including related intangible assets		198,674	186,549	172,108
Amortization of directors deferred compensation stock units		482	372	397
Amortization of stock compensation		7,447	5,646	2,219
Amortization of deferred financing costs		4,612	4,582	3,790
Amortization of debt discount and mark-to-market		(287)	1,686	3,385
Equity in (earnings) loss of unconsolidated joint ventures	[1]	6,081	(18,788)	3,172
Distributions of cumulative earnings from unconsolidated joint ventures		8,186	6,120	5,644
Gain on change of control of interests			(15,347)
Realized (gains) losses and unrealized losses on disposition of rental property, net		(2,364)	(109,666)	(53,261)
Gain on sale of investments in unconsolidated joint ventures		(23,131)	(5,670)	(6,448)
Loss (gain) from extinguishment of debt		421	(12,420)
Impairments				197,919
Changes in operating assets and liabilities:
Increase in unbilled rents receivable, net		(11,286)	(12,775)	(1,760)
Increase in deferred charges, goodwill and other assets		(19,711)	(33,878)	(22,854)
Decrease (increase) in accounts receivable, net		2,831	596	(2,178)
Increase (decrease) in accounts payable, accrued expenses and other liabilities		(9,012)	(14,535)	6,960
Decrease in rents received in advance and security deposits		(1,817)	(3,297)	(2,408)
Increase (decrease) in accrued interest payable		1,296	(9,362)	4,822
Net cash provided by operating activities		196,140	100,107	169,455
CASH FLOWS FROM INVESTING ACTIVITIES
Rental property acquisitions and related intangibles		(619,350)	(407,869)	(70,455)
Rental property additions and improvements		(90,068)	(121,582)	(94,073)
Development of rental property and other related costs		(267,845)	(206,955)	(81,073)
Proceeds from the sales of rental property		311,923	607,457	81,049
Proceeds from the sale of investments in unconsolidated joint ventures		110,269	6,420	6,448
Investments in notes receivable		(47,049)
Repayment of notes receivable		74,945	500	8,250
Investment in unconsolidated joint ventures		(36,060)	(35,930)	(78,027)
Distributions in excess of cumulative earnings from unconsolidated joint ventures		5,877	22,231	6,445
Proceeds from investment receivable		3,625
Decrease (increase) in restricted cash		8,027	(1,934)	(1,098)
Net cash provided by investing activities		(545,706)	(137,662)	(222,534)
CASH FLOW FROM FINANCING ACTIVITIES
Borrowings from revolving credit facility		730,000	1,165,000	334,000
Repayment of revolving credit facility		(866,000)	(1,034,000)	(179,000)
Repayment of senior unsecured notes		(250,000)	(448,339)
Borrowings from unsecured term loan		325,000	350,000
Proceeds from mortgages and loans payable		513,989	455,190	10,752
Repayment of mortgages, loans payable and other obligations		(156,760)	(349,426)	(43,133)
Acquisition of noncontrolling interests		(2,021)	(37,946)
Issuance of redeemable noncontrolling interests, net		139,002
Payment of contingent consideration				(1,167)
Payment of financing costs		(9,230)	(9,414)	(2,998)
Contributions from (to) noncontrolling interests		(19)	1,065	2,140
Payment of dividends and distributions		(77,826)	(60,041)	(59,987)
Net cash provided by financing activities		346,135	32,089	60,607
Net (decrease) increase in cash and cash equivalents		(3,431)	(5,466)	7,528
Cash and cash equivalents, beginning of period		31,611	37,077	29,549
Cash and cash equivalents, end of period		28,180	31,611	37,077
Mack-Cali Realty LP [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)		33,718	130,294	(142,052)
Adjustments to reconcile net income to net cash provided by Operating activities:
Depreciation and amortization, including related intangible assets		198,674	186,549	172,108
Amortization of directors deferred compensation stock units		482	372	397
Amortization of stock compensation		7,447	5,646	2,219
Amortization of deferred financing costs		4,612	4,582	3,790
Amortization of debt discount and mark-to-market		(287)	1,686	3,385
Equity in (earnings) loss of unconsolidated joint ventures		6,081	(18,788)	3,172
Distributions of cumulative earnings from unconsolidated joint ventures		8,186	6,120	5,644
Gain on change of control of interests			(15,347)
Realized (gains) losses and unrealized losses on disposition of rental property, net		(2,364)	(109,666)	(53,261)
Gain on sale of investments in unconsolidated joint ventures		(23,131)	(5,670)	(6,448)
Loss (gain) from extinguishment of debt		421	(12,420)
Impairments				197,919
Changes in operating assets and liabilities:
Increase in unbilled rents receivable, net		(11,286)	(12,775)	(1,760)
Increase in deferred charges, goodwill and other assets		(19,711)	(33,878)	(22,854)
Decrease (increase) in accounts receivable, net		2,831	596	(2,178)
Increase (decrease) in accounts payable, accrued expenses and other liabilities		(9,012)	(14,535)	6,960
Decrease in rents received in advance and security deposits		(1,817)	(3,297)	(2,408)
Increase (decrease) in accrued interest payable		1,296	(9,362)	4,822
Net cash provided by operating activities		196,140	100,107	169,455
CASH FLOWS FROM INVESTING ACTIVITIES
Rental property acquisitions and related intangibles		(619,350)	(407,869)	(70,455)
Rental property additions and improvements		(90,068)	(121,582)	(94,073)
Development of rental property and other related costs		(267,845)	(206,955)	(81,073)
Proceeds from the sales of rental property		311,923	607,457	81,049
Proceeds from the sale of investments in unconsolidated joint ventures		110,269	6,420	6,448
Investments in notes receivable		(47,049)
Repayment of notes receivable		74,945	500	8,250
Investment in unconsolidated joint ventures		(36,060)	(35,930)	(78,027)
Distributions in excess of cumulative earnings from unconsolidated joint ventures		5,877	22,231	6,445
Proceeds from investment receivable		3,625
Decrease (increase) in restricted cash		8,027	(1,934)	(1,098)
Net cash provided by investing activities		(545,706)	(137,662)	(222,534)
CASH FLOW FROM FINANCING ACTIVITIES
Borrowings from revolving credit facility		730,000	1,165,000	334,000
Repayment of revolving credit facility		(866,000)	(1,034,000)	(179,000)
Repayment of senior unsecured notes		(250,000)	(448,339)
Borrowings from unsecured term loan		325,000	350,000
Proceeds from mortgages and loans payable		513,989	455,190	10,752
Repayment of mortgages, loans payable and other obligations		(156,760)	(349,426)	(43,133)
Acquisition of noncontrolling interests		(2,021)	(37,946)
Issuance of redeemable noncontrolling interests, net		139,002
Payment of contingent consideration				(1,167)
Payment of financing costs		(9,230)	(9,414)	(2,998)
Contributions from (to) noncontrolling interests		(19)	1,065	2,140
Payment of dividends and distributions		(77,826)	(60,041)	(59,987)
Net cash provided by financing activities		346,135	32,089	60,607
Net (decrease) increase in cash and cash equivalents		(3,431)	(5,466)	7,528
Cash and cash equivalents, beginning of period		31,611	37,077	29,549
Cash and cash equivalents, end of period		$ 28,180	$ 31,611	$ 37,077
[1]	Amounts are net of amortization of basis differences of $792, $436 and $336 for the years ended December 31, 2017, 2016 and 2015, respectively.

Organization And Basis Of Prese

Organization And Basis Of Presentation	12 Months Ended
	Dec. 31, 2017
Organization And Basis Of Presentation [Line Items]
Organization And Basis Of Presentation	1. ORGANIZATION AND BASIS OF PRESENTATION  Organization Mack-Cali Realty Corporation, a Maryland corporation, together with its subsidiaries (collectively, the “ General Partner ”), is a fully-integrated, self-administered, self-managed real estate investment trust (“REIT”) . The General Partner controls Mack-Cali Realty, L.P., a Delaware limited partnership, together with its subsidiaries (collectively, the “Operating Partnership”), as its sole general partner and owned an 89.6 percent and 89.5 percent common unit interest in the Operating Partnership as of December 31, 2017 and December 31, 2016 , respectively. The General Partner’s business is the ownership of interests in and operation of the Operating Partnership and all of the General Partner’s expenses are incurred for the benefit of the Operating Partnership. The General Partner is reimbursed by the Operating Partnership for all expenses it incurs relating to the ownership and operation of the Operating Partnership.  The Operating Partnership conducts the business of providing leasing, management, acquisition, development, and tenant-related services for its General Partner. The Operating Partnership, through its operating divisions and subsidiaries, including the Mack-Cali property-owning partnerships and limited liability companies, is the entity through which all of the General Partner’s operations are conducted. Unless stated otherwise or the context requires, the “Company” refers to the General Partner and its subsidiaries, including the Operating Partnership and its subsidiaries.  As of December 31, 2017 , the Company owned or had interests in 157 properties, consisting of 69 office and 70 flex properties, totaling approximately 17.7 million square feet, leased to approximately 900 commercial tenants, and 18 multi-family rental properties containing 5,826 apartments , plus developable land (collectively, the “Properties”). The Properties are comprised of 69 office buildings totaling approximately 14.1 million square feet (which include four buildings aggregating approximately 0.5 million square feet owned by unconsolidated joint ventures in which the Company has investment interests), 56 office/flex buildings totaling approximately 3.1 million square feet, six industrial/warehouse buildings totaling approximately 387,400 square feet, 18 multi-family properties totaling 5,826 apartments (which include eight properties aggregating 3,275 apartments owned by unconsolidated joint ventures in which the Company has investment interests), six parking/retail properties totaling approximately 137,100 square feet (which include two buildings aggregating 81,700 square feet owned by unconsolidated joint ventures in which the Company has investment interests), a hotel (which is owned by an unconsolidated joint venture in which the Company has an investment interest) and a parcel of land leased to others. The Properties are located in six states, primarily in the Northeast, plus the District of Columbia.  BASIS OF PRESENTATION The accompanying consolidated financial statements include all accounts of the Company, its majority-owned and/or controlled subsidiaries, which consist principally of the Operating Partnership and variable interest entities for which the Company has determined itself to be the primary beneficiary, if any. See Note 2: Significant Accounting Policies – Investments in Unconsolidated Joint Ventures, for the Company’s treatment of unconsolidated joint venture interests. Intercompany accounts and transactions have been eliminated.  Accounting Standards Codification (“ASC”) 810, Consolidation, provides guidance on the identification of entities for which control is achieved through means other than voting rights (“variable interest entities” or “VIEs”) and the determination of which business enterprise, if any, should consolidate the VIEs. Generally, the consideration of whether an entity is a VIE applies when either: (1) the equity investors (if any) lack (i) the ability to make decisions about the entity's activities through voting or similar rights, (ii) the obligation to absorb the expected losses of the entity, or (iii) the right to receive the expected residual returns of the entity; (2) the equity investment at risk is insufficient to finance that entity’s activities without additional subordinated financial support; or (3) the equity investors have voting rights that are not proportionate to their economic interests and substantially all of the activities of the entity involve or are conducted on behalf of an investor with a disproportionately small voting interest. The Company consolidates VIEs in which it is considered to be the primary beneficiary. The primary beneficiary is defined by the entity having both of the following characteristics: (1) the power to direct the activities that, when taken together, most significantly impact the variable interest entity’s performance: and (2) the obligation to absorb losses and right to receive the returns from the VIE that would be significant to the VIE.  On January 1, 2016, the Company adopted accounting guidance under ASC 810, Consolidation, modifying the analysis it must perform to determine whether it should consolidate certain types of legal entities. The guidance does not amend the existing disclosure requirements for variable interest entities or voting interest model entities. The guidance, however, modified the requirements to qualify under the voting interest model. Under the revised guidance, the Operating Partnership will be a variable interest entity of the parent company, Mack-Cali Realty Corporation. As the Operating Partnership is already consolidated in the balance sheets of Mack-Cali Realty Corporation, the identification of this entity as a variable interest entity has no impact on the consolidated financial statements of Mack-Cali Realty Corporation. There were no other legal entities qualifying under the scope of the revised guidance that were consolidated as a result of the adoption.  As of December 31, 2017 and 2016 , the Company’s investments in consolidated real estate joint ventures , which are variable interest entities in which the Company is deemed to be the primary beneficiary , other than Roseland Residential, L.P. (See Note 3: Rockpoint Transaction), have total real estate assets of $215.5 million and $201.9 million, respectively, mortgages of $81.2 million and $78.4 million, respectively, and other liabilities of $19.3 million and $19.2 million, respectively.  The financial statements have been prepared in conformity with GAAP. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. These estimates and assumptions are based on management’s historical experience that are believed to be reasonable at the time. However, because future events and their effects cannot be determined with certainty, the determination of estimates requires the exercise of judgment. Actual results could differ from those estimates. Certain reclassifications have been made to prior period amounts in order to conform wi th current period presentation.
Mack-Cali Realty LP [Member]
Organization And Basis Of Presentation [Line Items]
Organization And Basis Of Presentation	1. ORGANIZATION AND BASIS OF PRESENTATION  Organization Mack-Cali Realty Corporation, a Maryland corporation, together with its subsidiaries (collectively, the “ General Partner ”), is a fully-integrated, self-administered, self-managed real estate investment trust (“REIT”) . The General Partner controls Mack-Cali Realty, L.P., a Delaware limited partnership, together with its subsidiaries (collectively, the “Operating Partnership”), as its sole general partner and owned an 89.6 percent and 89.5 percent common unit interest in the Operating Partnership as of December 31, 2017 and December 31, 2016 , respectively. The General Partner’s business is the ownership of interests in and operation of the Operating Partnership and all of the General Partner’s expenses are incurred for the benefit of the Operating Partnership. The General Partner is reimbursed by the Operating Partnership for all expenses it incurs relating to the ownership and operation of the Operating Partnership.  The Operating Partnership conducts the business of providing leasing, management, acquisition, development, and tenant-related services for its General Partner. The Operating Partnership, through its operating divisions and subsidiaries, including the Mack-Cali property-owning partnerships and limited liability companies, is the entity through which all of the General Partner’s operations are conducted. Unless stated otherwise or the context requires, the “Company” refers to the General Partner and its subsidiaries, including the Operating Partnership and its subsidiaries.  As of December 31, 2017 , the Company owned or had interests in 157 properties, consisting of 69 office and 70 flex properties, totaling approximately 17.7 million square feet, leased to approximately 900 commercial tenants, and 18 multi-family rental properties containing 5,826 apartments , plus developable land (collectively, the “Properties”). The Properties are comprised of 69 office buildings totaling approximately 14.1 million square feet (which include four buildings aggregating approximately 0.5 million square feet owned by unconsolidated joint ventures in which the Company has investment interests), 56 office/flex buildings totaling approximately 3.1 million square feet, six industrial/warehouse buildings totaling approximately 387,400 square feet, 18 multi-family properties totaling 5,826 apartments (which include eight properties aggregating 3,275 apartments owned by unconsolidated joint ventures in which the Company has investment interests), six parking/retail properties totaling approximately 137,100 square feet (which include two buildings aggregating 81,700 square feet owned by unconsolidated joint ventures in which the Company has investment interests), a hotel (which is owned by an unconsolidated joint venture in which the Company has an investment interest) and a parcel of land leased to others. The Properties are located in six states, primarily in the Northeast, plus the District of Columbia.  BASIS OF PRESENTATION The accompanying consolidated financial statements include all accounts of the Company, its majority-owned and/or controlled subsidiaries, which consist principally of the Operating Partnership and variable interest entities for which the Company has determined itself to be the primary beneficiary, if any. See Note 2: Significant Accounting Policies – Investments in Unconsolidated Joint Ventures, for the Company’s treatment of unconsolidated joint venture interests. Intercompany accounts and transactions have been eliminated.  Accounting Standards Codification (“ASC”) 810, Consolidation, provides guidance on the identification of entities for which control is achieved through means other than voting rights (“variable interest entities” or “VIEs”) and the determination of which business enterprise, if any, should consolidate the VIEs. Generally, the consideration of whether an entity is a VIE applies when either: (1) the equity investors (if any) lack (i) the ability to make decisions about the entity's activities through voting or similar rights, (ii) the obligation to absorb the expected losses of the entity, or (iii) the right to receive the expected residual returns of the entity; (2) the equity investment at risk is insufficient to finance that entity’s activities without additional subordinated financial support; or (3) the equity investors have voting rights that are not proportionate to their economic interests and substantially all of the activities of the entity involve or are conducted on behalf of an investor with a disproportionately small voting interest. The Company consolidates VIEs in which it is considered to be the primary beneficiary. The primary beneficiary is defined by the entity having both of the following characteristics: (1) the power to direct the activities that, when taken together, most significantly impact the variable interest entity’s performance: and (2) the obligation to absorb losses and right to receive the returns from the VIE that would be significant to the VIE.  On January 1, 2016, the Company adopted accounting guidance under ASC 810, Consolidation, modifying the analysis it must perform to determine whether it should consolidate certain types of legal entities. The guidance does not amend the existing disclosure requirements for variable interest entities or voting interest model entities. The guidance, however, modified the requirements to qualify under the voting interest model. Under the revised guidance, the Operating Partnership will be a variable interest entity of the parent company, Mack-Cali Realty Corporation. As the Operating Partnership is already consolidated in the balance sheets of Mack-Cali Realty Corporation, the identification of this entity as a variable interest entity has no impact on the consolidated financial statements of Mack-Cali Realty Corporation. There were no other legal entities qualifying under the scope of the revised guidance that were consolidated as a result of the adoption.  As of December 31, 2017 and 2016 , the Company’s investments in consolidated real estate joint ventures , which are variable interest entities in which the Company is deemed to be the primary beneficiary , other than Roseland Residential, L.P. (See Note 3: Rockpoint Transaction), have total real estate assets of $215.5 million and $201.9 million, respectively, mortgages of $81.2 million and $78.4 million, respectively, and other liabilities of $19.3 million and $19.2 million, respectively.  The financial statements have been prepared in conformity with GAAP. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. These estimates and assumptions are based on management’s historical experience that are believed to be reasonable at the time. However, because future events and their effects cannot be determined with certainty, the determination of estimates requires the exercise of judgment. Actual results could differ from those estimates. Certain reclassifications have been made to prior period amounts in order to conform wi th current period presentation.

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Significant Accounting Policies [Line Items]
Significant Accounting Policies	2. SIGNIFICANT ACCOUNTING POLICIES  Rental Property Rental properties are stated at cost less accumulated depreciation and amortization. Costs directly related to the acquisition, development and construction of rental properties are capitalized. Acquisition–related costs were expensed as incurred through December 31, 2016. The Company early adopted the recently issued FASB guidance Accounting Standards Update (“ASU”) 2017-01 on January 1, 2017 which revises the definition of a business and is expected to result in more transactions to be accounted for as asset acquisitions and significantly limit transactions that would be accounted for as business combinations. Where an acquisition has been determined to be an asset acquisition, acquisition-related costs are capitalized. Capitalized development and construction costs include pre-construction costs essential to the development of the property, development and construction costs, interest, property taxes, insurance, salaries and other project costs incurred during the period of development. Capitalized development and construction salaries and related costs approximated $ 2.2 million, $ 2.6 million and $4.2 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. Included in total rental property is construction, tenant improvement and development in-progress of $ 559.5 million and $ 361.1 million as of December 31, 2017 and 2016 , respectively. Ordinary repairs and maintenance are expensed as incurred; major replacements and betterments, which improve or extend the life of the asset, are capitalized and depreciated over their estimated useful lives. Fully-depreciated assets are removed from the accounts.  The Company considers a construction project as substantially completed and held available for occupancy upon the substantial completion of tenant improvements, but no later than one year from cessation of major construction activity (as distinguished from activities such as routine maintenance and cleanup). If portions of a rental project are substantially completed and occupied by tenants, or held available for occupancy, and other portions have not yet reached that stage, the substantially completed portions are accounted for as a separate project. The Company allocates costs incurred between the portions under construction and the portions substantially completed and held available for occupancy, primarily based on a percentage of the relative square footage of each portion, and capitalizes only those costs associated with the portion under construction.  Properties are depreciated using the straight-line method over the estimated useful lives of the assets. The estimated useful lives are as follows:   Leasehold interests Remaining lease term Buildings and improvements 5 to 40 years Tenant improvements The shorter of the term of the  related lease or useful life Furniture, fixtures and equipment 5 to 10 years  Upon acquisition of rental property, the Company estimates the fair value of acquired tangible assets, consisting of land, building and improvements, and identified intangible assets and liabilities assumed, generally consisting of the fair value of (i) above and below market leases, (ii) in-place leases and (iii) tenant relationships. The Company allocates the purchase price to the assets acquired and liabilities assumed based on their fair values. The Company records goodwill or a gain on bargain purchase (if any) if the net assets acquired/liabilities assumed differ from the purchase consideration of a business transaction.  In estimating the fair value of the tangible and intangible assets acquired, the Company considers information obtained about each property as a result of its due diligence and marketing and leasing activities, and utilizes various valuation methods, such as estimated cash flow projections utilizing appropriate discount and capitalization rates, estimates of replacement costs net of depreciation, and available market information. The fair value of the tangible assets of an acquired property considers the value of the property as if it were vacant.  Above-market and below-market lease values for acquired properties are initially recorded based on the present value (using a discount rate which reflects the risks associated with the leases acquired) of the difference between (i) the contractual amounts to be paid pursuant to each in-place lease and (ii) management’s estimate of fair market lease rates for each corresponding in-place lease, measured over a period equal to the remaining term of the lease for above-market leases and the remaining initial term plus the term of any below-market fixed rate renewal options for below-market leases. The capitalized above-market lease values are amortized as a reduction of base rental revenue over the remaining terms of the respective leases, and the capitalized below-market lease values are amortized as an increase to base rental revenue over the remaining initial terms plus the terms of any below-market fixed rate renewal options of the respective leases.  Other intangible assets acquired include amounts for in-place lease values and tenant relationship values, which are based on management’s evaluation of the specific characteristics of each tenant’s lease and the Company’s overall relationship with the respective tenant. Factors to be considered by management in its analysis of in-place lease values include an estimate of carrying costs during hypothetical expected lease-up periods considering current market conditions, and costs to execute similar leases. In estimating carrying costs, management includes real estate taxes, insurance and other operating expenses and estimates of lost rentals at market rates during the expected lease-up periods, depending on local market conditions. In estimating costs to execute similar leases, management considers leasing commissions, legal and other related expenses. Characteristics considered by management in valuing tenant relationships include the nature and extent of the Company’s existing business relationships with the tenant, growth prospects for developing new business with the tenant, the tenant’s credit quality and expectations of lease renewals. The value of in-place leases are amortized to expense over the remaining initial terms of the respective leases. The value of tenant relationship intangibles are amortized to expense over the anticipated life of the relationships.  On a periodic basis, management assesses whether there are any indicators that the value of the Company’s rental properties held for use may be impaired. In addition to identifying any specific circumstances which may affect a property or properties, management considers other criteria for determining which properties may require assessment for potential impairment. The criteria considered by management include reviewing low leased percentages, significant near-term lease expirations, current and historical operating and/or cash flow losses, near-term mortgage debt maturities and/or other factors, including those that might impact the Company’s intent and ability to hold the property. A property’s value is impaired only if management’s estimate of the aggregate future cash flows (undiscounted and without interest charges) to be generated by the property is less than the carrying value of the property. To the extent impairment has occurred, the impairment loss shall be measured as the excess of the carrying value of the property over the fair value of the property. The Company’s estimates of aggregate future cash flows expected to be generated by each property are based on a number of assumptions. These assumptions are generally based on management’s experience in its local real estate markets and the effects of current market conditions. The assumptions are subject to economic and market uncertainties including, among others, demand for space, competition for tenants, changes in market rental rates, and costs to operate each property. As these factors are difficult to predict and are subject to future events that may alter management’s assumptions, the future cash flows estimated by management in its impairment analyses may not be achieved, and actual losses or impairments may be realized in the future.  Rental Property Held for Sale When assets are identified by management as held for sale, the Company discontinues depreciating the assets and estimates the sales price, net of selling costs, of such assets. The Company generally considers assets to be held for sale when the transaction has received appropriate corporate authority, and there are no significant contingencies relating to the sale. If, in management’s opinion, the estimated net sales price, net of selling costs, of the assets which have been identified as held for sale is less than the carrying value of the assets, a valuation allowance (which is recorded as unrealized losses on disposition of rental property) is established. If circumstances arise that previously were considered unlikely and, as a result, the Company decides not to sell a property previously classified as held for sale, the property is reclassified as held and used. A property that is reclassified is measured and recorded individually at the lower of (a) its carrying value before the property was classified as held for sale, adjusted for any depreciation (amortization) expense that would have been recognized had the property been continuously classified as held and used, or (b) the fair value at the date of the subsequent decision not to sell.  Investments in Unconsolidated Joint Ventures The Company accounts for its investments in unconsolidated joint ventures under the equity method of accounting. The Company applies the equity method by initially recording these investments at cost, as Investments in Unconsolidated Joint Ventures, subsequently adjusted for equity in earnings and cash contributions and distributions. The outside basis portion of the Company’s joint ventures is amortized over the anticipated useful lives of the underlying ventures’ tangible and intangible assets acquired and liabilities assumed. Generally, the Company would discontinue applying the equity method when the investment (and any advances) is reduced to zero and would not provide for additional losses unless the Company has guaranteed obligations of the venture or is otherwise committed to providing further financial support for the investee. If the venture subsequently generates income, the Company only recognizes its share of such income to the extent it exceeds its share of previously unrecognized losses.  If the venture subsequently makes distributions and the Company does not have an implied or actual commitment to support the operations of the venture, including a general partner interest in the investee, the Company will not record a basis less than zero, rather such amounts will be recorded as equity in earnings of unconsolidated joint ventures. On a periodic basis, management assesses whether there are any indicators that the value of the Company’s investments in unconsolidated joint ventures may be impaired. An investment is impaired only if management’s estimate of the value of the investment is less than the carrying value of the investment, and such decline in value is deemed to be other than temporary. To the extent impairment has occurred, the loss shall be measured as the excess of the carrying value of the investment over the value of the investment. The Company’s estimates of value for each investment (particularly in real estate joint ventures) are based on a number of assumptions that are subject to economic and market uncertainties including, among others, demand for space, competition for tenants, changes in market rental rates, and operating costs. As these factors are difficult to predict and are subject to future events that may alter management’s assumptions, the values estimated by management in its impairment analyses may not be realized, and actual losses or impairment may be realized in the future. See Note 4: Investments in Unconsolidated Joint Ventures. Cash and Cash Equivalents All highly liquid investments with an original maturity of three months or less when purchased are considered to be cash equivalents. Deferred Financing Costs Costs incurred in obtaining financing are capitalized and amortized over the term of the related indebtedness. Deferred financing costs are presented in the balance sheet as a direct deduction from the carrying value of the debt liability to which they relate, except deferred financing costs related to the revolving credit facility, which are presented in deferred charges, goodwill and other assets. In all cases, amortization of such costs is included in interest expense and was $ 4,612,000 , $ 4,582,000 and $ 3,790,000 for the years ended December 31, 2017 , 2016 and 2015 , respectively. If a financing obligation is extinguished early, any unamortized deferred financing costs are written off and included in gains (losses) from extinguishment of debt. Included in loss from extinguishment of debt, net of gains, of $0.4 million, $30.5 million and zero for the years ended December 31, 2017 , 2016 and 2015 were unamortized deferred financing costs which were written off amounting to $0.4 million, $ 0.7 million and zero , respectively. Deferred Leasing Costs Costs incurred in connection with successfully executed commercial leases are capitalized and amortized on a straight-line basis over the terms of the related leases and included in depreciation and amortization. Unamortized deferred leasing costs are charged to amortization expense upon early termination of the lease. Certain employees of the Company are compensated for providing leasing services to the Properties. The portion of such compensation related to commercial leases, which is capitalized and amortized, and included in deferred charges, goodwill and other assets, net was approximately $ 3,146,000 , $ 3,270,000 and $ 3,521,000 for the years ended December 31, 2017 , 2016 and 2015 , respectively. Goodwill Goodwill represents the excess of the purchase price over the fair value of net tangible and intangible assets acquired in a business combination. Goodwill is allocated to various reporting units, as applicable. Each of the Company’s segments consists of a reporting unit. Goodwill is not amortized. Management performs an annual impairment test for goodwill during the fourth quarter and between annual tests, management evaluates the recoverability of goodwill whenever events or changes in circumstances indicate that the carrying value of goodwill may not be fully recoverable. In its impairment tests of goodwill, management first assesses qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying value. If based on this assessment, management determines that the fair value of the reporting unit is not less than its carrying value, then performing the additional two-step impairment test is unnecessary. If the carrying value of goodwill exceeds its fair value, an impairment charge is recognized. The Company determined that its goodwill was not impaired at December 31, 2017 after management performed its impairment tests. Derivative Instruments The Company measures derivative instruments, including certain derivative instruments embedded in other contracts, at fair value and records them as an asset or liability, depending on the Company’s rights or obligations under the applicable derivative contract. For derivatives designated and qualifying as fair value hedges, the changes in the fair value of both the derivative instrument and the hedged item are recorded in earnings. For derivatives designated as cash flow hedges, the effective portions of the derivative are reported in other comprehensive income (“OCI”) and are subsequently reclassified into earnings when the hedged item affects earnings. Changes in fair value of derivative instruments not designated as hedging and ineffective portions of hedges are recognized in earnings in the affected period. Revenue Recognition Base rental revenue is recognized on a straight-line basis over the terms of the respective leases. Unbilled rents receivable represents the cumulative amount by which straight-line rental revenue exceeds rents currently billed in accordance with the lease agreements.  Above-market and below-market lease values for acquired properties are initially recorded based on the present value (using a discount rate which reflects the risks associated with the leases acquired) of the difference between (i) the contractual amounts to be paid pursuant to each in-place lease and (ii) management’s estimate of fair market lease rates for each corresponding in-place lease, measured over a period equal to the remaining term of the lease for above-market leases and the remaining initial term plus the term of any below-market fixed-rate renewal options for below-market leases. The capitalized above-market lease values for acquired properties are amortized as a reduction of base rental revenue over the remaining terms of the respective leases, and the capitalized below-market lease values are amortized as an increase to base rental revenue over the remaining initial terms plus the terms of any below-market fixed-rate renewal options of the respective leases.  Escalations and recoveries from tenants are received from tenants for certain costs as provided in the lease agreements. These costs generally include real estate taxes, utilities, insurance, common area maintenance and other recoverable costs. See Note 13: Tenant Leases.  Real estate services revenue includes property management, development, construction and leasing commission fees and other services, and payroll and related costs reimbursed from clients. Fee income derived from the Company’s unconsolidated joint ventures (which are capitalized by such ventures) are recognized to the extent attributable to the unaffiliated ownership interests.  Parking income includes income from parking spaces leased to tenants and others.  Other income includes income from tenants for additional services arranged for by the Company and income from tenants for early lease terminations.    Allowance for Doubtful Accounts Management performs a detailed review of amounts due from tenants to determine if an allowance for doubtful accounts is required based on factors affecting the collectability of the accounts receivable balances. The factors considered by management in determining which individual tenant receivable balances, or aggregate receivable balances, require a collectability allowance include the age of the receivable, the tenant’s payment history, the nature of the charges, any communications regarding the charges and other related information. Management’s estimate of the allowance for doubtful accounts requires management to exercise significant judgment about the timing, frequency and severity of collection losses, which affects the allowance and net income. Income and Other Taxes The General Partner has elected to be taxed as a REIT under Sections 856 through 860 of the Internal Revenue Code of 1986, as amended (the “IRS Code”). As a REIT, the General Partner generally will not be subject to corporate federal income tax on net income that it currently distributes to its shareholders, provided that the General Partner satisfies certain organizational and operational requirements including the requirement to distribute at least 90 percent of its REIT taxable income (determined by excluding any net capital gains) to its shareholders. If and to the extent the General Partner retains and does not distribute any net capital gains, the General Partner will be required to pay federal, state and local taxes, as applicable, on such net capital gains at the rate applicable to capital gains of a corporation.  The Operating Partnership is a partnership, and, as a result, all income and losses of the partnership are allocated to the partners for inclusion in their respective tax returns. Accordingly, no provision or benefit for income taxes has been made in the accompanying financial statements.  As of December 31, 2017 , the estimated net basis of the rental property for federal income tax purposes was lower than the net assets as reported in the Operating Partnership’s financial statements by approximately $231,067,000 . The Operating Partnership’s taxable income for the year ended December 31, 2017 was estimated to be approximately $97,037,000 and for the years ended December 31, 2016 and 2015 was approximately $30,208,000 and $63,285,000 , respectively. The differences between book income and taxable income primarily result from differences in depreciation expenses, the recording of rental income, differences in the deductibility of certain expenses for tax purposes, differences in revenue recognition and the rules for tax purposes of a property exchange.  The General Partner has elected to treat certain of its corporate subsidiaries as taxable REIT subsidiaries (each a “TRS”). In general, a TRS of the General Partner may perform additional services for tenants of the Company and generally may engage in any real estate or non-real estate related business (except for the operation or management of health care facilities or lodging facilities or the providing to any person, under a franchise, license or otherwise, rights to any brand name under which any lodging facility or health care facility is operated). A TRS is subject to corporate federal income tax. The General Partner has conducted business through its TRS entities for certain property management, development, construction and other related services, as well as to hold a joint venture interest in a hotel and other matters.  The deferred tax balance at December 31, 2017 is $ 11.7 million which has been fully reserved through a valuation allowance. New tax reform legislation enacted in late 2017 reduces the corporate tax rate to 21 percent, effective January 1, 2018. Consequently, the Company’s deferred tax assets were re-measured to reflect the reduction in the future U.S. corporate income tax rate as of the enactment date . As a result, the Company recorded a decrease related to deferred tax assets of $5.3 million and a decrease to the associated valuation allowance of $5.3 million at December 31, 2017. If the General Partner fails to qualify as a REIT in any taxable year, the Company will be subject to federal income tax on its taxable income at regular corporate tax rates. The Company is subject to certain state and local taxes.  Pursuant to the amended provisions related to uncertain tax provisions of ASC 740, Income Taxes, the Company recognized no material adjustments regarding its tax accounting treatment. The Company expects to recognize interest and penalties related to uncertain tax positions, if any, as income tax expense, which is included in general and administrative expense.  In the normal course of business, the Company or one of its subsidiaries is subject to examination by federal, state and local jurisdictions in which it operates, where applicable. As of December 31, 2017 , the tax years that remain subject to examination by the major tax jurisdictions under the statute of limitations are generally from the year 2013 forward.  Earnings Per Share or Unit The Company presents both basic and diluted earnings per share or unit (“EPS or EPU”). Basic EPS or EPU excludes dilution and is computed by dividing net income available to common shareholders or unitholders by the weighted average number of shares or units outstanding for the period. Diluted EPS or EPU reflects the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock, where such exercise or conversion would result in a lower EPS or EPU from continuing operations amount. Shares or Units whose issuance is contingent upon the satisfaction of certain conditions shall be considered outstanding and included in the computation of diluted EPS or EPU as follows (i) if all necessary conditions have been satisfied by the end of the period (the events have occurred), those shares or units shall be included as of the beginning of the period in which the conditions were satisfied (or as of the date of the grant, if later) or (ii) if all necessary conditions have not been satisfied by the end of the period, the number of contingently issuable shares or units included in diluted EPS or EPU shall be based on the number of shares or units, if any, that would be issuable if the end of the reporting period were the end of the contingency period (for example, the number of shares or units that would be issuable based on current period earnings or period-end market price) and if the result would be dilutive. Those contingently issuable shares or units shall be included in the denominator of diluted EPS or EPU as of the beginning of the period (or as of the date of the grant, if later).  Dividends and Distributions Payable The dividends and distributions payable at December 31, 2017 represents dividends payable to common shareholders ( 89,914,658 shares) and distributions payable to noncontrolling interest unitholders of the Operating Partnership ( 10,438,855 common units and 1,230,877 LTIP units) for all such holders of record as of January 3, 2018 with respect to the fourth quarter 2017 . The fourth quarter 2017 common stock dividends and unit distributions of $ 0.20 per common share, common unit and LTIP unit were approved by the General Partner’s Board of Directors on December 12, 2017 and paid on January 12, 2018 .  The dividends and distributions payable at December 31, 2016 represents dividends payable to common shareholders ( 89,696,824 shares) and distributions payable to noncontrolling interest unitholders of the Operating Partnership ( 10,488,105 common units and 657,373 LTIP units) for all such holders of record as of January 5, 2017 with respect to the fourth quarter 2016 . The fourth quarter 2016 common stock dividends and unit distributions of $ 0.15 per common share, common unit and LTIP unit were approved by the General Partner’s Board of Directors on December 13, 2016 and paid on January 13, 2017 .  The Company has determined that the $ 0.70 dividend per common share paid during the year ended December 31, 2017 represented 100 percent ordinary income; the $ 0.60 dividend per common share paid during the year ended December 31, 2016 represented 100 percent return of capital; and the $ 0.60 dividend per common share paid during the year ended December 31, 2015 represented approximately 90 percent ordinary income and approximately 10 percent return of capital.  Costs Incurred For Stock Issuances Costs incurred in connection with the Company’s stock issuances are reflected as a reduction of additional paid ‑in capital.  Stock Compensation The Company accounts for stock compensation in accordance with the provisions of ASC 718, Compensation-Stock Compensation. These provisions require that the estimated fair value of restricted stock (“Restricted Stock Awards”), performance share units, long term incentive plan awards and stock options at the grant date be amortized ratably into expense over the appropriate vesting period. The Company recorded stock compensation expense of $ 7,447,000 , $ 5,646,000 and $ 2,219,000 for the years ended December 31, 2017 , 2016 and 2015 , respectively.  Other Comprehensive Income (Loss) Other comprehensive income (loss) includes items that are recorded in equity, such as effective portions of derivatives designated as cash flow hedges or unrealized holding gains or losses on marketable securities available for sale.  Fair Value Hierarchy The standard Fair Value Measurements specifies a hierarchy of valuation techniques based upon whether the inputs to those valuation techniques reflect assumptions other market participants would use based upon market data obtained from independent sources (observable inputs). The following summarizes the fair value hierarchy:  · Level 1: Quoted prices in active markets that are unadjusted and accessible at the measurement date for identical, unrestricted assets or liabilities; · Level 2: Quoted prices for identical assets and liabilities in markets that are inactive, quoted prices for similar assets and liabilities in active markets or financial instruments for which significant inputs are observable, either directly or indirectly, such as interest rates and yield curves that are observable at commonly quoted intervals and · Level 3: Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable.  In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, the level in the fair value hierarchy within which the fair value measurement in its entirety falls has been determined based on the lowest level input that is significant to the fair value measurement in its entirety. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment and considers factors specific to the asset or liability.  Impact Of Recently-Issued Accounting Standards In May 2014, the FASB issued Accounting Standards Update (“ASU”) 2014-09 Revenue from Contracts with Customers (Topic 606) ("ASU 2014-09"). ASU 2014-09 is a comprehensive new revenue recognition model requiring a company to recognize revenue to depict the transfer of goods or services to a customer at an amount reflecting the consideration it expects to receive in exchange for those goods or services. In adopting ASU 2014-09, companies may use either a full retrospective or a modified retrospective approach. Additionally, this guidance requires improved disclosures regarding the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. ASU 2014-09 is effective for the first interim period within annual reporting periods beginning after December 15, 2017, and early adoption is permitted for periods beginning after December 15, 2016. While lease contracts with customers, which constitute the majority of the Company’s revenues, are a specific scope exception of ASU 2014-09, certain of the Company’s revenue streams , including management services and other fee income, may be impacted by ASU 2014-09. The Company ha s evaluate d the effect the adoption will have on the Company’s revenue , and does not expect it will have a material impact on the Company’s consolidated financial statements, and also does not believe the adoption will significantly affect the timing of the recognition of the Company’s services income. The Company plans to adopt this standard using the modified retrospective approach, which requires a cumulative effect adjustment as of the date of adoption.  In February 2016, the FASB issued ASU 2016-02, modifying the principles for the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e. lessees and lessors). The new standard requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase by the lessee. This classification will determine whether lease expense is recognized based on an effective interest method or on a straight line basis over the term of the lease, respectively. A lessee is also required to record a right-of-use asset and a lease liability for all leases with a term of greater than 12 months regardless of their classification. Leases with a term of 12 months or less will be accounted for in the same manner as operating leases today. The new standard requires lessors to account for leases using an approach that is substantially equivalent to existing guidance for sales-type leases, direct financing leases and operating leases. The guidance is expected to impact the consolidated financial statements as the Company has certain operating and land lease arrangements for which it is the lessee. The guidance supersedes previously issued guidance under ASC Topic 840 “Leases.” The guidance is effective on January 1, 2019, with early adoption permitted. The Company is currently in the process of evaluating the impact the adoption of ASU 2016-02 will have on the Company’s consolidated financial statements.  In August 2016, the FASB
Mack-Cali Realty LP [Member]
Significant Accounting Policies [Line Items]
Significant Accounting Policies	2. SIGNIFICANT ACCOUNTING POLICIES  Rental Property Rental properties are stated at cost less accumulated depreciation and amortization. Costs directly related to the acquisition, development and construction of rental properties are capitalized. Acquisition–related costs were expensed as incurred through December 31, 2016. The Company early adopted the recently issued FASB guidance Accounting Standards Update (“ASU”) 2017-01 on January 1, 2017 which revises the definition of a business and is expected to result in more transactions to be accounted for as asset acquisitions and significantly limit transactions that would be accounted for as business combinations. Where an acquisition has been determined to be an asset acquisition, acquisition-related costs are capitalized. Capitalized development and construction costs include pre-construction costs essential to the development of the property, development and construction costs, interest, property taxes, insurance, salaries and other project costs incurred during the period of development. Capitalized development and construction salaries and related costs approximated $ 2.2 million, $ 2.6 million and $4.2 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. Included in total rental property is construction, tenant improvement and development in-progress of $ 559.5 million and $ 361.1 million as of December 31, 2017 and 2016 , respectively. Ordinary repairs and maintenance are expensed as incurred; major replacements and betterments, which improve or extend the life of the asset, are capitalized and depreciated over their estimated useful lives. Fully-depreciated assets are removed from the accounts.  The Company considers a construction project as substantially completed and held available for occupancy upon the substantial completion of tenant improvements, but no later than one year from cessation of major construction activity (as distinguished from activities such as routine maintenance and cleanup). If portions of a rental project are substantially completed and occupied by tenants, or held available for occupancy, and other portions have not yet reached that stage, the substantially completed portions are accounted for as a separate project. The Company allocates costs incurred between the portions under construction and the portions substantially completed and held available for occupancy, primarily based on a percentage of the relative square footage of each portion, and capitalizes only those costs associated with the portion under construction.  Properties are depreciated using the straight-line method over the estimated useful lives of the assets. The estimated useful lives are as follows:   Leasehold interests Remaining lease term Buildings and improvements 5 to 40 years Tenant improvements The shorter of the term of the  related lease or useful life Furniture, fixtures and equipment 5 to 10 years  Upon acquisition of rental property, the Company estimates the fair value of acquired tangible assets, consisting of land, building and improvements, and identified intangible assets and liabilities assumed, generally consisting of the fair value of (i) above and below market leases, (ii) in-place leases and (iii) tenant relationships. The Company allocates the purchase price to the assets acquired and liabilities assumed based on their fair values. The Company records goodwill or a gain on bargain purchase (if any) if the net assets acquired/liabilities assumed differ from the purchase consideration of a business transaction.  In estimating the fair value of the tangible and intangible assets acquired, the Company considers information obtained about each property as a result of its due diligence and marketing and leasing activities, and utilizes various valuation methods, such as estimated cash flow projections utilizing appropriate discount and capitalization rates, estimates of replacement costs net of depreciation, and available market information. The fair value of the tangible assets of an acquired property considers the value of the property as if it were vacant.  Above-market and below-market lease values for acquired properties are initially recorded based on the present value (using a discount rate which reflects the risks associated with the leases acquired) of the difference between (i) the contractual amounts to be paid pursuant to each in-place lease and (ii) management’s estimate of fair market lease rates for each corresponding in-place lease, measured over a period equal to the remaining term of the lease for above-market leases and the remaining initial term plus the term of any below-market fixed rate renewal options for below-market leases. The capitalized above-market lease values are amortized as a reduction of base rental revenue over the remaining terms of the respective leases, and the capitalized below-market lease values are amortized as an increase to base rental revenue over the remaining initial terms plus the terms of any below-market fixed rate renewal options of the respective leases.  Other intangible assets acquired include amounts for in-place lease values and tenant relationship values, which are based on management’s evaluation of the specific characteristics of each tenant’s lease and the Company’s overall relationship with the respective tenant. Factors to be considered by management in its analysis of in-place lease values include an estimate of carrying costs during hypothetical expected lease-up periods considering current market conditions, and costs to execute similar leases. In estimating carrying costs, management includes real estate taxes, insurance and other operating expenses and estimates of lost rentals at market rates during the expected lease-up periods, depending on local market conditions. In estimating costs to execute similar leases, management considers leasing commissions, legal and other related expenses. Characteristics considered by management in valuing tenant relationships include the nature and extent of the Company’s existing business relationships with the tenant, growth prospects for developing new business with the tenant, the tenant’s credit quality and expectations of lease renewals. The value of in-place leases are amortized to expense over the remaining initial terms of the respective leases. The value of tenant relationship intangibles are amortized to expense over the anticipated life of the relationships.  On a periodic basis, management assesses whether there are any indicators that the value of the Company’s rental properties held for use may be impaired. In addition to identifying any specific circumstances which may affect a property or properties, management considers other criteria for determining which properties may require assessment for potential impairment. The criteria considered by management include reviewing low leased percentages, significant near-term lease expirations, current and historical operating and/or cash flow losses, near-term mortgage debt maturities and/or other factors, including those that might impact the Company’s intent and ability to hold the property. A property’s value is impaired only if management’s estimate of the aggregate future cash flows (undiscounted and without interest charges) to be generated by the property is less than the carrying value of the property. To the extent impairment has occurred, the impairment loss shall be measured as the excess of the carrying value of the property over the fair value of the property. The Company’s estimates of aggregate future cash flows expected to be generated by each property are based on a number of assumptions. These assumptions are generally based on management’s experience in its local real estate markets and the effects of current market conditions. The assumptions are subject to economic and market uncertainties including, among others, demand for space, competition for tenants, changes in market rental rates, and costs to operate each property. As these factors are difficult to predict and are subject to future events that may alter management’s assumptions, the future cash flows estimated by management in its impairment analyses may not be achieved, and actual losses or impairments may be realized in the future.  Rental Property Held for Sale When assets are identified by management as held for sale, the Company discontinues depreciating the assets and estimates the sales price, net of selling costs, of such assets. The Company generally considers assets to be held for sale when the transaction has received appropriate corporate authority, and there are no significant contingencies relating to the sale. If, in management’s opinion, the estimated net sales price, net of selling costs, of the assets which have been identified as held for sale is less than the carrying value of the assets, a valuation allowance (which is recorded as unrealized losses on disposition of rental property) is established. If circumstances arise that previously were considered unlikely and, as a result, the Company decides not to sell a property previously classified as held for sale, the property is reclassified as held and used. A property that is reclassified is measured and recorded individually at the lower of (a) its carrying value before the property was classified as held for sale, adjusted for any depreciation (amortization) expense that would have been recognized had the property been continuously classified as held and used, or (b) the fair value at the date of the subsequent decision not to sell.  Investments in Unconsolidated Joint Ventures The Company accounts for its investments in unconsolidated joint ventures under the equity method of accounting. The Company applies the equity method by initially recording these investments at cost, as Investments in Unconsolidated Joint Ventures, subsequently adjusted for equity in earnings and cash contributions and distributions. The outside basis portion of the Company’s joint ventures is amortized over the anticipated useful lives of the underlying ventures’ tangible and intangible assets acquired and liabilities assumed. Generally, the Company would discontinue applying the equity method when the investment (and any advances) is reduced to zero and would not provide for additional losses unless the Company has guaranteed obligations of the venture or is otherwise committed to providing further financial support for the investee. If the venture subsequently generates income, the Company only recognizes its share of such income to the extent it exceeds its share of previously unrecognized losses.  If the venture subsequently makes distributions and the Company does not have an implied or actual commitment to support the operations of the venture, including a general partner interest in the investee, the Company will not record a basis less than zero, rather such amounts will be recorded as equity in earnings of unconsolidated joint ventures. On a periodic basis, management assesses whether there are any indicators that the value of the Company’s investments in unconsolidated joint ventures may be impaired. An investment is impaired only if management’s estimate of the value of the investment is less than the carrying value of the investment, and such decline in value is deemed to be other than temporary. To the extent impairment has occurred, the loss shall be measured as the excess of the carrying value of the investment over the value of the investment. The Company’s estimates of value for each investment (particularly in real estate joint ventures) are based on a number of assumptions that are subject to economic and market uncertainties including, among others, demand for space, competition for tenants, changes in market rental rates, and operating costs. As these factors are difficult to predict and are subject to future events that may alter management’s assumptions, the values estimated by management in its impairment analyses may not be realized, and actual losses or impairment may be realized in the future. See Note 4: Investments in Unconsolidated Joint Ventures. Cash and Cash Equivalents All highly liquid investments with an original maturity of three months or less when purchased are considered to be cash equivalents. Deferred Financing Costs Costs incurred in obtaining financing are capitalized and amortized over the term of the related indebtedness. Deferred financing costs are presented in the balance sheet as a direct deduction from the carrying value of the debt liability to which they relate, except deferred financing costs related to the revolving credit facility, which are presented in deferred charges, goodwill and other assets. In all cases, amortization of such costs is included in interest expense and was $ 4,612,000 , $ 4,582,000 and $ 3,790,000 for the years ended December 31, 2017 , 2016 and 2015 , respectively. If a financing obligation is extinguished early, any unamortized deferred financing costs are written off and included in gains (losses) from extinguishment of debt. Included in loss from extinguishment of debt, net of gains, of $0.4 million, $30.5 million and zero for the years ended December 31, 2017 , 2016 and 2015 were unamortized deferred financing costs which were written off amounting to $0.4 million, $ 0.7 million and zero , respectively. Deferred Leasing Costs Costs incurred in connection with successfully executed commercial leases are capitalized and amortized on a straight-line basis over the terms of the related leases and included in depreciation and amortization. Unamortized deferred leasing costs are charged to amortization expense upon early termination of the lease. Certain employees of the Company are compensated for providing leasing services to the Properties. The portion of such compensation related to commercial leases, which is capitalized and amortized, and included in deferred charges, goodwill and other assets, net was approximately $ 3,146,000 , $ 3,270,000 and $ 3,521,000 for the years ended December 31, 2017 , 2016 and 2015 , respectively. Goodwill Goodwill represents the excess of the purchase price over the fair value of net tangible and intangible assets acquired in a business combination. Goodwill is allocated to various reporting units, as applicable. Each of the Company’s segments consists of a reporting unit. Goodwill is not amortized. Management performs an annual impairment test for goodwill during the fourth quarter and between annual tests, management evaluates the recoverability of goodwill whenever events or changes in circumstances indicate that the carrying value of goodwill may not be fully recoverable. In its impairment tests of goodwill, management first assesses qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying value. If based on this assessment, management determines that the fair value of the reporting unit is not less than its carrying value, then performing the additional two-step impairment test is unnecessary. If the carrying value of goodwill exceeds its fair value, an impairment charge is recognized. The Company determined that its goodwill was not impaired at December 31, 2017 after management performed its impairment tests. Derivative Instruments The Company measures derivative instruments, including certain derivative instruments embedded in other contracts, at fair value and records them as an asset or liability, depending on the Company’s rights or obligations under the applicable derivative contract. For derivatives designated and qualifying as fair value hedges, the changes in the fair value of both the derivative instrument and the hedged item are recorded in earnings. For derivatives designated as cash flow hedges, the effective portions of the derivative are reported in other comprehensive income (“OCI”) and are subsequently reclassified into earnings when the hedged item affects earnings. Changes in fair value of derivative instruments not designated as hedging and ineffective portions of hedges are recognized in earnings in the affected period. Revenue Recognition Base rental revenue is recognized on a straight-line basis over the terms of the respective leases. Unbilled rents receivable represents the cumulative amount by which straight-line rental revenue exceeds rents currently billed in accordance with the lease agreements.  Above-market and below-market lease values for acquired properties are initially recorded based on the present value (using a discount rate which reflects the risks associated with the leases acquired) of the difference between (i) the contractual amounts to be paid pursuant to each in-place lease and (ii) management’s estimate of fair market lease rates for each corresponding in-place lease, measured over a period equal to the remaining term of the lease for above-market leases and the remaining initial term plus the term of any below-market fixed-rate renewal options for below-market leases. The capitalized above-market lease values for acquired properties are amortized as a reduction of base rental revenue over the remaining terms of the respective leases, and the capitalized below-market lease values are amortized as an increase to base rental revenue over the remaining initial terms plus the terms of any below-market fixed-rate renewal options of the respective leases.  Escalations and recoveries from tenants are received from tenants for certain costs as provided in the lease agreements. These costs generally include real estate taxes, utilities, insurance, common area maintenance and other recoverable costs. See Note 13: Tenant Leases.  Real estate services revenue includes property management, development, construction and leasing commission fees and other services, and payroll and related costs reimbursed from clients. Fee income derived from the Company’s unconsolidated joint ventures (which are capitalized by such ventures) are recognized to the extent attributable to the unaffiliated ownership interests.  Parking income includes income from parking spaces leased to tenants and others.  Other income includes income from tenants for additional services arranged for by the Company and income from tenants for early lease terminations.    Allowance for Doubtful Accounts Management performs a detailed review of amounts due from tenants to determine if an allowance for doubtful accounts is required based on factors affecting the collectability of the accounts receivable balances. The factors considered by management in determining which individual tenant receivable balances, or aggregate receivable balances, require a collectability allowance include the age of the receivable, the tenant’s payment history, the nature of the charges, any communications regarding the charges and other related information. Management’s estimate of the allowance for doubtful accounts requires management to exercise significant judgment about the timing, frequency and severity of collection losses, which affects the allowance and net income. Income and Other Taxes The General Partner has elected to be taxed as a REIT under Sections 856 through 860 of the Internal Revenue Code of 1986, as amended (the “IRS Code”). As a REIT, the General Partner generally will not be subject to corporate federal income tax on net income that it currently distributes to its shareholders, provided that the General Partner satisfies certain organizational and operational requirements including the requirement to distribute at least 90 percent of its REIT taxable income (determined by excluding any net capital gains) to its shareholders. If and to the extent the General Partner retains and does not distribute any net capital gains, the General Partner will be required to pay federal, state and local taxes, as applicable, on such net capital gains at the rate applicable to capital gains of a corporation.  The Operating Partnership is a partnership, and, as a result, all income and losses of the partnership are allocated to the partners for inclusion in their respective tax returns. Accordingly, no provision or benefit for income taxes has been made in the accompanying financial statements.  As of December 31, 2017 , the estimated net basis of the rental property for federal income tax purposes was lower than the net assets as reported in the Operating Partnership’s financial statements by approximately $231,067,000 . The Operating Partnership’s taxable income for the year ended December 31, 2017 was estimated to be approximately $97,037,000 and for the years ended December 31, 2016 and 2015 was approximately $30,208,000 and $63,285,000 , respectively. The differences between book income and taxable income primarily result from differences in depreciation expenses, the recording of rental income, differences in the deductibility of certain expenses for tax purposes, differences in revenue recognition and the rules for tax purposes of a property exchange.  The General Partner has elected to treat certain of its corporate subsidiaries as taxable REIT subsidiaries (each a “TRS”). In general, a TRS of the General Partner may perform additional services for tenants of the Company and generally may engage in any real estate or non-real estate related business (except for the operation or management of health care facilities or lodging facilities or the providing to any person, under a franchise, license or otherwise, rights to any brand name under which any lodging facility or health care facility is operated). A TRS is subject to corporate federal income tax. The General Partner has conducted business through its TRS entities for certain property management, development, construction and other related services, as well as to hold a joint venture interest in a hotel and other matters.  The deferred tax balance at December 31, 2017 is $ 11.7 million which has been fully reserved through a valuation allowance. New tax reform legislation enacted in late 2017 reduces the corporate tax rate to 21 percent, effective January 1, 2018. Consequently, the Company’s deferred tax assets were re-measured to reflect the reduction in the future U.S. corporate income tax rate as of the enactment date . As a result, the Company recorded a decrease related to deferred tax assets of $5.3 million and a decrease to the associated valuation allowance of $5.3 million at December 31, 2017. If the General Partner fails to qualify as a REIT in any taxable year, the Company will be subject to federal income tax on its taxable income at regular corporate tax rates. The Company is subject to certain state and local taxes.  Pursuant to the amended provisions related to uncertain tax provisions of ASC 740, Income Taxes, the Company recognized no material adjustments regarding its tax accounting treatment. The Company expects to recognize interest and penalties related to uncertain tax positions, if any, as income tax expense, which is included in general and administrative expense.  In the normal course of business, the Company or one of its subsidiaries is subject to examination by federal, state and local jurisdictions in which it operates, where applicable. As of December 31, 2017 , the tax years that remain subject to examination by the major tax jurisdictions under the statute of limitations are generally from the year 2013 forward.  Earnings Per Share or Unit The Company presents both basic and diluted earnings per share or unit (“EPS or EPU”). Basic EPS or EPU excludes dilution and is computed by dividing net income available to common shareholders or unitholders by the weighted average number of shares or units outstanding for the period. Diluted EPS or EPU reflects the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock, where such exercise or conversion would result in a lower EPS or EPU from continuing operations amount. Shares or Units whose issuance is contingent upon the satisfaction of certain conditions shall be considered outstanding and included in the computation of diluted EPS or EPU as follows (i) if all necessary conditions have been satisfied by the end of the period (the events have occurred), those shares or units shall be included as of the beginning of the period in which the conditions were satisfied (or as of the date of the grant, if later) or (ii) if all necessary conditions have not been satisfied by the end of the period, the number of contingently issuable shares or units included in diluted EPS or EPU shall be based on the number of shares or units, if any, that would be issuable if the end of the reporting period were the end of the contingency period (for example, the number of shares or units that would be issuable based on current period earnings or period-end market price) and if the result would be dilutive. Those contingently issuable shares or units shall be included in the denominator of diluted EPS or EPU as of the beginning of the period (or as of the date of the grant, if later).  Dividends and Distributions Payable The dividends and distributions payable at December 31, 2017 represents dividends payable to common shareholders ( 89,914,658 shares) and distributions payable to noncontrolling interest unitholders of the Operating Partnership ( 10,438,855 common units and 1,230,877 LTIP units) for all such holders of record as of January 3, 2018 with respect to the fourth quarter 2017 . The fourth quarter 2017 common stock dividends and unit distributions of $ 0.20 per common share, common unit and LTIP unit were approved by the General Partner’s Board of Directors on December 12, 2017 and paid on January 12, 2018 .  The dividends and distributions payable at December 31, 2016 represents dividends payable to common shareholders ( 89,696,824 shares) and distributions payable to noncontrolling interest unitholders of the Operating Partnership ( 10,488,105 common units and 657,373 LTIP units) for all such holders of record as of January 5, 2017 with respect to the fourth quarter 2016 . The fourth quarter 2016 common stock dividends and unit distributions of $ 0.15 per common share, common unit and LTIP unit were approved by the General Partner’s Board of Directors on December 13, 2016 and paid on January 13, 2017 .  The Company has determined that the $ 0.70 dividend per common share paid during the year ended December 31, 2017 represented 100 percent ordinary income; the $ 0.60 dividend per common share paid during the year ended December 31, 2016 represented 100 percent return of capital; and the $ 0.60 dividend per common share paid during the year ended December 31, 2015 represented approximately 90 percent ordinary income and approximately 10 percent return of capital.  Costs Incurred For Stock Issuances Costs incurred in connection with the Company’s stock issuances are reflected as a reduction of additional paid ‑in capital.  Stock Compensation The Company accounts for stock compensation in accordance with the provisions of ASC 718, Compensation-Stock Compensation. These provisions require that the estimated fair value of restricted stock (“Restricted Stock Awards”), performance share units, long term incentive plan awards and stock options at the grant date be amortized ratably into expense over the appropriate vesting period. The Company recorded stock compensation expense of $ 7,447,000 , $ 5,646,000 and $ 2,219,000 for the years ended December 31, 2017 , 2016 and 2015 , respectively.  Other Comprehensive Income (Loss) Other comprehensive income (loss) includes items that are recorded in equity, such as effective portions of derivatives designated as cash flow hedges or unrealized holding gains or losses on marketable securities available for sale.  Fair Value Hierarchy The standard Fair Value Measurements specifies a hierarchy of valuation techniques based upon whether the inputs to those valuation techniques reflect assumptions other market participants would use based upon market data obtained from independent sources (observable inputs). The following summarizes the fair value hierarchy:  · Level 1: Quoted prices in active markets that are unadjusted and accessible at the measurement date for identical, unrestricted assets or liabilities; · Level 2: Quoted prices for identical assets and liabilities in markets that are inactive, quoted prices for similar assets and liabilities in active markets or financial instruments for which significant inputs are observable, either directly or indirectly, such as interest rates and yield curves that are observable at commonly quoted intervals and · Level 3: Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable.  In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, the level in the fair value hierarchy within which the fair value measurement in its entirety falls has been determined based on the lowest level input that is significant to the fair value measurement in its entirety. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment and considers factors specific to the asset or liability.  Impact Of Recently-Issued Accounting Standards In May 2014, the FASB issued Accounting Standards Update (“ASU”) 2014-09 Revenue from Contracts with Customers (Topic 606) ("ASU 2014-09"). ASU 2014-09 is a comprehensive new revenue recognition model requiring a company to recognize revenue to depict the transfer of goods or services to a customer at an amount reflecting the consideration it expects to receive in exchange for those goods or services. In adopting ASU 2014-09, companies may use either a full retrospective or a modified retrospective approach. Additionally, this guidance requires improved disclosures regarding the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. ASU 2014-09 is effective for the first interim period within annual reporting periods beginning after December 15, 2017, and early adoption is permitted for periods beginning after December 15, 2016. While lease contracts with customers, which constitute the majority of the Company’s revenues, are a specific scope exception of ASU 2014-09, certain of the Company’s revenue streams , including management services and other fee income, may be impacted by ASU 2014-09. The Company ha s evaluate d the effect the adoption will have on the Company’s revenue , and does not expect it will have a material impact on the Company’s consolidated financial statements, and also does not believe the adoption will significantly affect the timing of the recognition of the Company’s services income. The Company plans to adopt this standard using the modified retrospective approach, which requires a cumulative effect adjustment as of the date of adoption.  In February 2016, the FASB issued ASU 2016-02, modifying the principles for the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e. lessees and lessors). The new standard requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase by the lessee. This classification will determine whether lease expense is recognized based on an effective interest method or on a straight line basis over the term of the lease, respectively. A lessee is also required to record a right-of-use asset and a lease liability for all leases with a term of greater than 12 months regardless of their classification. Leases with a term of 12 months or less will be accounted for in the same manner as operating leases today. The new standard requires lessors to account for leases using an approach that is substantially equivalent to existing guidance for sales-type leases, direct financing leases and operating leases. The guidance is expected to impact the consolidated financial statements as the Company has certain operating and land lease arrangements for which it is the lessee. The guidance supersedes previously issued guidance under ASC Topic 840 “Leases.” The guidance is effective on January 1, 2019, with early adoption permitted. The Company is currently in the process of evaluating the impact the adoption of ASU 2016-02 will have on the Company’s consolidated financial statements.  In August 2016, the FASB

Recent Transactions

Recent Transactions	12 Months Ended
	Dec. 31, 2017
Recent Transactions [Line Items]
Recent Transactions	3. RECENT TRANSACTIONS  Management Changes On April 5, 2017, the Company announced that Michael J. DeMarco would be assuming the title of chief executive officer of the Company and Mitchell Rudin, formerly the chief executive officer, was being named the vice chairman of the Company effective April 4, 2017. Mr. DeMarco had joined the Company in 2015 as the president and chief operating officer.  On January 29, 2018, the Company announced the appointment of David J. Smetana as chief financial officer and Nicholas Hilton as executive vice president of leasing of the General Partner. Mr. Smetana will begin to perform his duties as chief financial officer and Anthony Krug shall cease to serve as chief financial officer immediately following the filing of this Annual Report on Form 10-K for the year ended December 31, 2017. Mr. Krug will remain an employee of the General Partner and will provide transition services through March 31, 2018. Mr. Hilton’s employment commenced on February 12, 2018 following the departure of Christopher DeLorenzo.  Acquisitions  201 7 The Company acquired the following office properties (which were determined to be asset acquisitions in accordance with ASU 2017-01) during the year ended December 31, 2017 (dollars in thousands) :    Acquisition # of Rentable Acquisition  Date Property Address Location Bldgs. Square Feet Cost  01/11/17 Red Bank portfolio (a) Red Bank, New Jersey 3 279,472 $ 27,228  03/06/17 Short Hills/Madison portfolio (b) Short Hills & Madison, New Jersey 6 1,113,028 367,361   Total Acquisitions 9 1,392,500 $ 394,589   (a) This acquisition was funded through borrowings under the Company's unsecured revolving credit facility.  (b) This acquisition was funded through borrowings under the Company’s unsecured revolving credit facility and a new $124.5 million loan secured by three of the properties.  The purchase prices were allocated to the net assets acquired, as follows (in thousands) :     Red Bank Short Hills/Madison  Portfolio Portfolio Total  Land and leasehold interest $ 7,914 $ 30,336 $ 38,250  Buildings and improvements and other assets 16,047 295,299 311,346  Above market leases (a) 118 6,367 6,485  In-place lease values (a) 3,171 45,604 48,775  27,250 377,606 404,856  Less: Below market lease values (a) (22) (10,245) (10,267)  Net assets recorded upon acquisition $ 27,228 $ 367,361 $ 394,589  (a) Above market, in-place and below market leases are being amortized over a weighted-average term of 5.4 years.  The Company acquired three developable land parcels located in Jersey City, Morris Township and Red Bank, New Jersey, for approximately $80 million during the year ended December 31, 2017. The acquisitions were funded using available cash and borrowings under the Company’s unsecured revolving credit facility.  2016 The Company acquired the following office properties during the year ended December 31, 2016 ( dollars in thousands) :     Acquisition # of Rentable Acquisition  Date Property Address Location Bldgs. Square Feet Cost  04/04/16 11 Martine Avenue (a) White Plains, New York 1 82,000 $ 10,750  04/07/16 320, 321 University Avenue (b) Newark, New Jersey 2 147,406 23,000  06/02/16 101 Wood Avenue South (c) Edison, New Jersey 1 262,841 82,300  07/01/16 111 River Street (c) Hoboken, New Jersey 1 566,215 210,761   Total Acquisitions 5 1,058,462 $ 326,811   (a) Acquisition represented four units of condominium interests which collectively comprise floors 2 through 5. Upon completion of the acquisition,  the Company owns the entire 14-story 262,000 square-foot building. The acquisition was funded using available cash.  (b) This acquisition was funded through borrowings under the Company’s unsecured revolving credit facility.  (c) This acquisition was funded using available cash and through borrowings under the Company’s unsecured revolving credit facility.  The purchase prices were allocated to the net assets acquired, as follows (in thousands) :    320,321  11 Martine University 101 Wood 111 River  Avenue Avenue Avenue Street  Land and leasehold interest $ 2,460 $ 7,305 $ 8,509 $ 204  Buildings and improvements 8,290 15,695 72,738 198,609  Above market leases (a) - - 58 617  In-place lease values (a) - - 6,743 43,801  Other assets - - - 11,279  88,048 254,510  Less: Below market lease values (a) - - (5,748) (43,749)  Net assets recorded upon acquisition $ 10,750 $ 23,000 $ 82,300 $ 210,761  (a) Above market, in-place and below market leases are being amortized over a weighted-average term of 8.1 years.  Properties Commencing Initial Operations The following properties commenced initial operations during the year ended December 31, 2016 ( dollars in thousands ):     Total  In-Service # of Development  Date Property Location Type Apartment Units Costs  12/01/16 Quarry Place at Tuckahoe Eastchester, NY Multi-Family 108 $ 56,961 (a)  12/01/16 The Chase II at Overlook Ridge Malden, MA Multi-Family 292 65,218 (b)  Totals 400 $ 122,179  (a) Development costs as of December 31, 2016 included approximately $5.6 million in land costs. (b) Development costs as of December 31, 2016 included approximately $10.8 million in land costs. As of December 31, 2016, the Company anticipates additional costs of approximately $9.7 million, which will be funded from a construction loan.  Consolidations  2017 On February 3, 2017, the Operating Partnership issued 42,800 shares of a new class of 3.5 percent Series A Preferred Limited Partnership Units of the Operating Partnership (the “Series A Units”) valued at $42.8 million. The Series A Units were issued to the Company’s partners in the Plaza VIII & IX Associates L.L.C. joint venture that owns a development site adjacent to the Company’s Harborside property in Jersey City, New Jersey as non-cash consideration for their approximate 37.5 percent interest in the joint venture. Concurrent with the issuance of the Series A Units, the Company purchased from other partners in the Plaza VIII & IX Associates L.L.C. joint venture their approximate 12.5 percent interest for approximately $14.3 million in cash. The results of these transactions increased the Company’s interests in the joint venture from 50 percent to 100 percent. Upon these acquisitions, the Company consolidated Plaza VIII & IX Associates L.L.C., a voting interest entity, substantially all of which is comprised of land for development. As an acquisition of the additional 50 percent of the land, the Company accounted for the transaction as an asset acquisition under a cost accumulation model, resulting in total consolidated assets of $60.6 million, substantially all of which is classified as land on the Balance Sheet.  On February 28, 2017, the Operating Partnership authorized the issuance of 9,213 shares of a new class of 3.5 percent Series A-1 Preferred Limited Partnership Units of the Operating Partnership (the “Series A-1 Units”). 9,122 Series A-1 Units were issued on February 28, 2017, valued at $9.1 million, to the Company’s partner in a joint venture with the Operating Partnership, which owns Monaco Towers in Jersey City, New Jersey that includes 523 apartment homes in two fifty -story towers with 558 parking spaces and 12,300 square feet of ground floor retail space. The Series A-1 Units were issued as non-cash consideration for the partner’s approximate 13.8 percent ownership interest in the joint venture to increase the Company’s unconsolidated investment to 29 percent. In April 2017, an additional 91 Series A-1 Units were issued by the Operating Partnership to purchase from other partners in the same joint venture their approximate 71.2 percent ownership interest for approximately $130.9 million in cash and $171.2 million in assumed debt in transactions which closed in April 2017. The results of these transactions increased the Company’s interests in the joint venture to 100 percent. Upon these acquisitions, the Company consolidated RoseGarden Monaco Holdings, L.L.C., a voting interest entity.  As an acquisition of the remaining interests in the venture which owns the Monaco Towers, the Company accounted for the transaction as an asset acquisition under a cost accumulation model, resulting in total consolidated net assets of $139.9 million which is allocated, as follows (in thousands):     Monaco Monaco  North South Total  Land and leasehold interest $ 27,300 $ 31,461 $ 58,761  Buildings and improvements and other assets 112,841 129,895 242,736  Above market leases (a) 350 - 350  In-place lease values (a) 4,585 4,913 9,498  Less: Below market lease values (a) (141) (118) (259)  144,935 166,151 311,086  Less: Debt assumed at fair value (79,544) (91,656) (171,200)  Net assets recorded upon consolidation $ 65,391 $ 74,495 $ 139,886  (a) Above market, in-place and below market leases are being amortized over a weighted-average term of 8 months.  2016 On January 5, 2016, the Company, which held a 50 percent subordinated interest in the unconsolidated joint venture, Overlook Ridge Apartment Investors LLC, a 371 -unit multi-family operating property located in Malden, Massachusetts, acquired the remaining interest for $39.8 million in cash plus the assumption of a first mortgage loan secured by the property with a principal balance of $52.7 million. The cash portion of the acquisition was funded primarily through borrowings under the Company’s unsecured revolving credit facility. Upon acquisition, the Company consolidated the asset and accordingly, remeasured its equity interests, as required by the FASB’s consolidation guidance, at fair value (based upon the income approach using current rates and market cap rates and discount rates). As a result, the Company recorded a gain on change of control of interests of $10.2 million in the year ended December 31, 2016. On January 19, 2016, the Company repaid the assumed loan and obtained a new loan secured by the property in the amount of $72.5 million, which bears interest at 3.625 percent and matures in February 2023 . See Note 9: Mortgages, Loans Payable and Other Obligations.  During the second quarter 2016, the Company, which held a 38.25 percent subordinate interest in the unconsolidated Portside Apartment Developers, L.L.C., a joint venture which owns a 175 -unit operating multi-family property located in East Boston, Massachusetts, acquired the remaining interests of its joint venture partners for $39.6 million in cash plus the assumption of a mortgage loan secured by the property with a principal balance of $42.5 million. The cash portion of the acquisition was funded primarily through borrowings under the Company’s unsecured revolving credit facility. Upon acquisition, the Company consolidated the asset and accordingly, remeasured its equity interests, as required by the FASB’s consolidation guidance, at fair value (based upon the income approach using current rates and market cap rates and discount rates). As a result, the Company recorded a gain on change of control of interests of $5.2 million in the year ended December 31, 2016. On July 8, 2016, the Company repaid the assumed loan and obtained a new loan secured by the property in the amount of $59 million, which bears interest at 3.44 percent and matures in August 2023 . See Note 9: Mortgages, Loans Payable and Other Obligations.  The purchase prices were preliminarily allocated to the net assets acquired upon consolidation, as follows (in thousands) :     Overlook Portside  Ridge Apts  Land and leasehold interest $ 11,072 $ -  Buildings and improvements 87,793 73,713  Furniture, fixtures and equipment 1,695 1,038  Other assets 237 10,181  In-place lease values (a) 4,389 2,637  Less: Below market lease values (a) (489) (242)  Sub Total 104,697 87,327   Less: Debt assumed (52,662) (42,500)   Net assets recorded upon consolidation $ 52,035 $ 44,827  (a) In-place lease values and below-market lease values are be ing amortized over a weighted average term of 7.4 months .  Other Investments in 2016 On April 26, 2016, the Company acquired the remaining non-controlling interest in a development project located in Weehawken, New Jersey for $36.4 million. The project includes developable land for approximately 1,100 multi-family units, 290,000 square feet of office space, a 52.5 percent ownership interest in Port Imperial 4/5 Garage and Retail operating properties. The initial phase, Port Imperial South 11, a 295 -unit multi-family project, began construction in the first quarter 2016.  Dispositions /Rental Property Held for Sale  201 7 The Company disposed of the following office properties during the year ended December 31, 201 7 (dollars in thousands) :     Realized  Gains  Rentable Net Net (losses)/  Disposition # of Square Sales Carrying Unrealized  Date Property/Address Location Bldgs. Feet Proceeds Value Losses, net  01/30/17 Cranford portfolio Cranford, New Jersey 6 435,976 $ 26,598 $ 22,736 $ 3,862  01/31/17 440 Route 22 East (a) Bridgewater, New Jersey 1 198,376 10,074 10,069 5  02/07/17 3 Independence Way Princeton, New Jersey 1 111,300 11,549 9,910 1,639  05/15/17 103 Carnegie Center Princeton, New Jersey 1 96,000 15,063 8,271 6,792  08/29/17 400 Chestnut Ridge Road Woodcliff Lake, New Jersey 1 89,200 6,891 7,498 (607)  08/30/17 140 E. Ridgewood Avenue Paramus, New Jersey 1 239,680 30,201 30,737 (536)  08/30/17 Bergen portfolio Woodcliff Lake, Paramus and 5 1,061,544 86,973 (c) 135,121 (48,148)  Rochelle Park, New Jersey  09/11/17 377 Summerhill Road East Brunswick, New Jersey 1 40,000 3,221 2,172 1,049  09/13/17 700 Executive Boulevard Elmsford, New York - - (b) 5,717 970 4,747  09/20/17 Totowa Portfolio Totowa, New Jersey 13 499,243 63,624 27,630 35,994  09/27/17 890 Mountain Avenue (d) New Providence, New Jersey 1 80,000 4,852 6,139 (1,287)  09/28/17 135 Chestnut Ridge Road Montvale, New Jersey 1 66,150 5,844 (e) 2,929 2,915  09/29/17 Moorestown portfolio Moorestown and Burlington, New Jersey 26 1,260,398 73,393 (f) 56,186 17,207  10/19/17 1 Enterprise Boulevard Yonkers, New York - - (b) 3,230 1,380 1,850  11/15/17 61 South Paramus Road Paramus, New Jersey 1 269,191 23,255 37,184 (13,929)  12/06/17 300 Tice Boulevard Woodcliff Lake, New Jersey 1 230,000 28,847 25,705 3,142  Sub-total 60 4,677,058 399,332 384,637 14,695   Unrealized losses on rental property held for sale (12,331)   Totals 60 4,677,058 $ 399,332 $ 384,637 $ 2,364   (a) The Company recorded a valuation allowance of $7.7 million on this property during the year ended December 31, 2016.  (b) This disposition is of a ground leased land property.  (c) At closing, the Company provided short term seller financing aggregating $65 million through mortgage notes receivable to the buyers. These notes were paid off in November  and December 2017.  (d) The Company recorded an impairment charge of $7.0 million on this property during the year ended December 31, 2015.  (e) The Company recorded an impairment charge of $4.2 million on this property during the year ended December 31, 2015. $5.9 million of the sales proceeds from this sale were  held by a qualified intermediary, which is noncash and recorded in deferred charges, goodwill and other assets as of December 31, 2017. See Note 5: Deferred Charges,  Goodwill and Other Assets, Net.  (f) $15.3 million of the sales proceeds from this sale were held by a qualified intermediary, which is noncash and recorded in deferred charges, goodwill and other assets  as of December 31, 2017. See Note 5: Deferred Charges, Goodwill and Other Assets, Net.   The Company identified as held for sale 21 office properties totaling approximately 2 million square feet as of December 31, 2017. The properties are located in Parsippany, Paramus, Rochelle Park, Hamilton and Wall, New Jersey and White Plains, New York. The total estimated sales proceeds from the sales are expected to be approximately $223 million. The Company determined that the carrying value of seven of the office properties was not expected to be recovered from estimated net sales proceeds and accordingly recognized an unrealized loss allowance of $12.3 million during the year ended December 31, 2017. In February 2018, the Company completed the disposition of one of these properties for sales proceeds of $25.9 million.  The following table summarizes the rental property held for sale, net, as of December 31, 2017: (dollars in thousands)     December 31,  2017  Land $ 37,024  Buildings and improvements 273,388  Less: Accumulated depreciation (126,503)  Less: Unrealized losses on properties held for sale (12,331)  Rental property held for sale,net $ 171,578   Other assets and liabilities related to the rental properties held for sale, as of December 31, 2017, include $9.8 million in deferred charges, and other assets, $4.7 million in Unbilled rents receivable and $ 4.6 million in Accounts payable, accrued expenses and other liabilities. Approximately $13.4 million of these assets and $ 0.3 million of these liabilities are expected to be written off with the completion of the sales.  2016 The Company disposed of the following office and multi-family properties during the year ended December 31, 201 6 (dollars in thousands) :     Realized  Gains  Net Net (losses)/  Disposition # of Sales Carrying Unrealized  Date Property/Address Location Bldgs. Proceeds Value Losses, net  03/11/16 2 Independence Way (a) Princeton, New Jersey 1 $ 4,119 $ 4,283 $ (164)  03/24/16 1201 Connecticut Avenue, NW Washington, D.C. 1 90,591 31,827 58,764  04/26/16 125 Broad Street (b) New York, New York 1 192,323 200,183 (7,860)  05/09/16 9200 Edmonston Road Greenbelt, Maryland 1 4,083 (c) 3,837 246  05/18/16 1400 L Street Washington, D.C. 1 68,399 30,053 38,346  07/14/16 600 Parsippany Road Parsippany, New Jersey 1 10,465 (d) 5,875 4,590  07/14/16 4,5,6 Century Drive (e) Parsippany, New Jersey 3 14,533 17,308 (2,775)  08/11/16 Andover Place Andover, Massachusetts 1 39,863 37,150 2,713  09/26/16 222,233 Mount Airy Road (f) Basking Ridge, New Jersey 2 8,817 9,039 (222)  09/27/16 10 Mountainview Road Upper Saddle River, New Jersey 1 18,990 19,571 (581)  11/07/16 100 Willowbrook, 2,3,4 Paragon (g) Freehold, New Jersey 4 14,634 19,377 (4,743)  12/05/16 4 Becker Farm Road Roseland, New Jersey 1 41,400 (h) 31,001 10,399  12/09/16 101,103,105 Eisenhower Parkway Roseland, New Jersey 3 46,423 45,999 424  12/22/16 Capital Office Park, Ivy Lane (i) Greenbelt, Maryland 6 46,570 65,064 (18,494)  12/22/16 100 Walnut Avenue Clark, New Jersey 1 28,428 7,529 20,899  12/22/16 20 Commerce Drive Cranford, New Jersey 1 28,878 13,071 15,807  12/29/16 4200 Parliament Place (j) Lanham, Maryland 1 5,965 5,983 (18)  Sub-total 30 664,481 547,150 117,331   Unrealized losses on rental property held for sale (7,665)   Totals 30 $ 664,481 $ 547,150 $ 109,666   (a) The Company recorded an impairment charge of $3.2 million on this property during the year ended December 31, 2015.  (b) The Company recorded impairment charges of $83.2 million on this property during the year ended December 31, 2015.  (c) The Company transferred the deed for this property to the lender in satisfaction of its obligations. The Company recorded an impairment charge of $3.0 million  on this property during the year ended December 31, 2012.  (d) $10.5 million of the net sales proceeds from this sale were held by a qualified intermediary. The Company received these proceeds on January 11, 2017.  (e) The Company recorded impairment charges of $9.8 million on these properties during the year ended December 31, 2015.  (f) The Company recorded impairment charges of $1.0 million on these properties during the year ended December 31, 2015.  (g) The Company recorded impairment charges of $7.4 million on these properties during the year ended December 31, 2015.  (h) The Company transferred the deed for this property to the lender in satisfaction of its obligations.  (i) The Company recorded impairment charges of $66.5 million on these properties during the year ended December 31, 2015.  (j) The Company recorded an impairment charge of $4.2 million on this property during the year ended December 31, 2015.  As of December 31, 2016, the Company identified as held for sale eight office properties totaling approximately 750,000 square feet. The properties were located in Princeton, Cranford and Bridgewater, New Jersey. The Company determined that the carrying value of one of the office properties was not expected to be recovered from estimated net sales proceeds and accordingly recognized an unrealized loss allowance of $7.7 million at December 31, 2016. In January and February 2017, the Company completed the disposition of these properties for sales proceeds of approximately $45.8 million.  The following table summarizes the rental property held for sale, net, as of December 31, 2016: (dollars in thousands)     December 31,  2016  Land $ 10,934  Buildings and improvements 68,266  Less: Accumulated depreciation (31,792)  Less: Unrealized losses on properties held for sale (7,665)  Rental property held for sale,net $ 39,743  Other assets and liabilities related to the rental properties held for sale, as of December 31, 2016, include $1.7 million in deferred charges, and other assets, $1.2 million in Unbilled rents receivable, $ 1.1 million in Accounts payable, accrued expenses and other liabilities, and $1.9 million in Rents received in advance and security deposits. Approximately $2.9 million of these assets and $ 0.5 million of these liabilities are expected to be written off with the completion of the sales.  Rockpoint Transaction On February 27, 2017, the Company, Roseland Residential Trust (“RRT”), the Company’s wholly-owned subsidiary through which the Company conducts its multi-family residential real estate operations, Roseland Residential, L.P. (“RRLP”), the operating partnership through which RRT conducts all of its operations, and certain other affiliates of the Company entered into an equity investment agreement (the “Investment Agreement”) with Rockpoint Group, L.L.C. and certain of its affiliates (collectively, “Rockpoint”). The Investment Agreement provides for multiple equity investments by Rockpoint in RRLP from time to time for up to an aggregate of $300 million of equity units of limited partnership interests of RRLP (the “Rockpoint Units”). The initial closing under the Investment Agreement occurred on March 10, 2017 for $150 million of Rockpoint Units. Additional closings of Rockpoint Units to be issued and sold to Rockpoint pursuant to the Investment Agreement may occur from time to time in increments of not less than $10 million per closing, with the balance of the full $300 million by March 1, 2019. See Note 14: Redeemable Noncontrolling Interests.  RRLP has been identified as a variable interest entity in which the Company is deemed to be the primary beneficiary. As of December 31, 2017 and December 31, 2016, the Company’s consolidated RRLP entity had total assets of $1.9 billion and $1.3 billion, respectively, total mortgages and loan payable of $769.7 million and $480.7 million, respectively, and other liabilities of $95.9 million and $40.1 million, respectively.  Unconsolidated Joint Venture Activity On April 1, 2016, the Company bought out its partner PruRose Riverwalk G, L.L.C. for $11.3 million and increased its subordinated interest in Riverwalk G Urban Renewal, L.L.C. from 25 percent to 50 percent using borrowings on the Company’s unsecured credit facility. Riverwalk G Urban Renewal, L.L.C., owns a 316 -unit operating multi-family property located in West New York, New Jersey. Concurrent with the refinancing in October 2016, the Company executed an agreement with the remaining partner which converted the 50 percent subordinated interest to 22.5 percent pari passu interest.  On May 26, 2016, the Company sold its 50 percent interest in Port Imperial South 15, L.L.C. (“RiversEdge”) and its 20 percent interest in Port Imperial South 13 Urban Renewal, L.L.C. (“RiverParc”), joint ventures that own the 236 -unit and the 280 -unit multi-family operating properties, respectively, located in Weehawken, New Jersey for $6.4 million. The Company realized a gain on the sale of $5.7 million.  On January 31 , 2017, the Company sold its interest in the KPG-P 100 IMW JV, LLC, Keystone-Penn and Keystone-Tristate joint ventures that own operating properties, located in Philadelphia, Pennsylvania for a n aggregate sales price of $9.7 million and realized a gain on the sale of the unconsolidated joint venture of $7.4 million.  On February 15, 2017, the Company sold its 7.5 percent interest in the Elmajo Urban Renewal Associates, LLC and Estuary Urban Renewal Unit B, LLC joint ventures that own operating multi-family properties located in Weehawken, New Jersey for a sales price of $5.1 million and realized a gain on the sale of the unconsolidated joint venture of $5.1 million.  On September 21, 2017, the RoseGarden Monaco, L.L.C. joint venture agreement was terminated. Accordingly, the Company wrote off the carrying value of its investment in the joint venture and recorded a loss of $1.4 million on the disposition of its joint venture interest.  On September 29, 2017, the Company sold its interests in the KPG-MCG Curtis joint venture that owns an operating property located in Philadelphia, Pennsylvania for a sales price of $102.5 million, which included the retirement of the Company’s share in a mortgage payable of $75 million, and realized a gain on the sale of the unconsolidated joint venture of $12 million. $5.6 million of the net sales proceeds from this sale were held by a qualified intermediary, which is considered non cash and recorded in deferred charges, goodwill and other assets. See Note 5: Deferred Charges, Goodwill and Other Assets, Net.
Mack-Cali Realty LP [Member]
Recent Transactions [Line Items]
Recent Transactions	3. RECENT TRANSACTIONS  Management Changes On April 5, 2017, the Company announced that Michael J. DeMarco would be assuming the title of chief executive officer of the Company and Mitchell Rudin, formerly the chief executive officer, was being named the vice chairman of the Company effective April 4, 2017. Mr. DeMarco had joined the Company in 2015 as the president and chief operating officer.  On January 29, 2018, the Company announced the appointment of David J. Smetana as chief financial officer and Nicholas Hilton as executive vice president of leasing of the General Partner. Mr. Smetana will begin to perform his duties as chief financial officer and Anthony Krug shall cease to serve as chief financial officer immediately following the filing of this Annual Report on Form 10-K for the year ended December 31, 2017. Mr. Krug will remain an employee of the General Partner and will provide transition services through March 31, 2018. Mr. Hilton’s employment commenced on February 12, 2018 following the departure of Christopher DeLorenzo.  Acquisitions  201 7 The Company acquired the following office properties (which were determined to be asset acquisitions in accordance with ASU 2017-01) during the year ended December 31, 2017 (dollars in thousands) :    Acquisition # of Rentable Acquisition  Date Property Address Location Bldgs. Square Feet Cost  01/11/17 Red Bank portfolio (a) Red Bank, New Jersey 3 279,472 $ 27,228  03/06/17 Short Hills/Madison portfolio (b) Short Hills & Madison, New Jersey 6 1,113,028 367,361   Total Acquisitions 9 1,392,500 $ 394,589   (a) This acquisition was funded through borrowings under the Company's unsecured revolving credit facility.  (b) This acquisition was funded through borrowings under the Company’s unsecured revolving credit facility and a new $124.5 million loan secured by three of the properties.  The purchase prices were allocated to the net assets acquired, as follows (in thousands) :     Red Bank Short Hills/Madison  Portfolio Portfolio Total  Land and leasehold interest $ 7,914 $ 30,336 $ 38,250  Buildings and improvements and other assets 16,047 295,299 311,346  Above market leases (a) 118 6,367 6,485  In-place lease values (a) 3,171 45,604 48,775  27,250 377,606 404,856  Less: Below market lease values (a) (22) (10,245) (10,267)  Net assets recorded upon acquisition $ 27,228 $ 367,361 $ 394,589  (a) Above market, in-place and below market leases are being amortized over a weighted-average term of 5.4 years.  The Company acquired three developable land parcels located in Jersey City, Morris Township and Red Bank, New Jersey, for approximately $80 million during the year ended December 31, 2017. The acquisitions were funded using available cash and borrowings under the Company’s unsecured revolving credit facility.  2016 The Company acquired the following office properties during the year ended December 31, 2016 ( dollars in thousands) :     Acquisition # of Rentable Acquisition  Date Property Address Location Bldgs. Square Feet Cost  04/04/16 11 Martine Avenue (a) White Plains, New York 1 82,000 $ 10,750  04/07/16 320, 321 University Avenue (b) Newark, New Jersey 2 147,406 23,000  06/02/16 101 Wood Avenue South (c) Edison, New Jersey 1 262,841 82,300  07/01/16 111 River Street (c) Hoboken, New Jersey 1 566,215 210,761   Total Acquisitions 5 1,058,462 $ 326,811   (a) Acquisition represented four units of condominium interests which collectively comprise floors 2 through 5. Upon completion of the acquisition,  the Company owns the entire 14-story 262,000 square-foot building. The acquisition was funded using available cash.  (b) This acquisition was funded through borrowings under the Company’s unsecured revolving credit facility.  (c) This acquisition was funded using available cash and through borrowings under the Company’s unsecured revolving credit facility.  The purchase prices were allocated to the net assets acquired, as follows (in thousands) :    320,321  11 Martine University 101 Wood 111 River  Avenue Avenue Avenue Street  Land and leasehold interest $ 2,460 $ 7,305 $ 8,509 $ 204  Buildings and improvements 8,290 15,695 72,738 198,609  Above market leases (a) - - 58 617  In-place lease values (a) - - 6,743 43,801  Other assets - - - 11,279  88,048 254,510  Less: Below market lease values (a) - - (5,748) (43,749)  Net assets recorded upon acquisition $ 10,750 $ 23,000 $ 82,300 $ 210,761  (a) Above market, in-place and below market leases are being amortized over a weighted-average term of 8.1 years.  Properties Commencing Initial Operations The following properties commenced initial operations during the year ended December 31, 2016 ( dollars in thousands ):     Total  In-Service # of Development  Date Property Location Type Apartment Units Costs  12/01/16 Quarry Place at Tuckahoe Eastchester, NY Multi-Family 108 $ 56,961 (a)  12/01/16 The Chase II at Overlook Ridge Malden, MA Multi-Family 292 65,218 (b)  Totals 400 $ 122,179  (a) Development costs as of December 31, 2016 included approximately $5.6 million in land costs. (b) Development costs as of December 31, 2016 included approximately $10.8 million in land costs. As of December 31, 2016, the Company anticipates additional costs of approximately $9.7 million, which will be funded from a construction loan.  Consolidations  2017 On February 3, 2017, the Operating Partnership issued 42,800 shares of a new class of 3.5 percent Series A Preferred Limited Partnership Units of the Operating Partnership (the “Series A Units”) valued at $42.8 million. The Series A Units were issued to the Company’s partners in the Plaza VIII & IX Associates L.L.C. joint venture that owns a development site adjacent to the Company’s Harborside property in Jersey City, New Jersey as non-cash consideration for their approximate 37.5 percent interest in the joint venture. Concurrent with the issuance of the Series A Units, the Company purchased from other partners in the Plaza VIII & IX Associates L.L.C. joint venture their approximate 12.5 percent interest for approximately $14.3 million in cash. The results of these transactions increased the Company’s interests in the joint venture from 50 percent to 100 percent. Upon these acquisitions, the Company consolidated Plaza VIII & IX Associates L.L.C., a voting interest entity, substantially all of which is comprised of land for development. As an acquisition of the additional 50 percent of the land, the Company accounted for the transaction as an asset acquisition under a cost accumulation model, resulting in total consolidated assets of $60.6 million, substantially all of which is classified as land on the Balance Sheet.  On February 28, 2017, the Operating Partnership authorized the issuance of 9,213 shares of a new class of 3.5 percent Series A-1 Preferred Limited Partnership Units of the Operating Partnership (the “Series A-1 Units”). 9,122 Series A-1 Units were issued on February 28, 2017, valued at $9.1 million, to the Company’s partner in a joint venture with the Operating Partnership, which owns Monaco Towers in Jersey City, New Jersey that includes 523 apartment homes in two fifty -story towers with 558 parking spaces and 12,300 square feet of ground floor retail space. The Series A-1 Units were issued as non-cash consideration for the partner’s approximate 13.8 percent ownership interest in the joint venture to increase the Company’s unconsolidated investment to 29 percent. In April 2017, an additional 91 Series A-1 Units were issued by the Operating Partnership to purchase from other partners in the same joint venture their approximate 71.2 percent ownership interest for approximately $130.9 million in cash and $171.2 million in assumed debt in transactions which closed in April 2017. The results of these transactions increased the Company’s interests in the joint venture to 100 percent. Upon these acquisitions, the Company consolidated RoseGarden Monaco Holdings, L.L.C., a voting interest entity.  As an acquisition of the remaining interests in the venture which owns the Monaco Towers, the Company accounted for the transaction as an asset acquisition under a cost accumulation model, resulting in total consolidated net assets of $139.9 million which is allocated, as follows (in thousands):     Monaco Monaco  North South Total  Land and leasehold interest $ 27,300 $ 31,461 $ 58,761  Buildings and improvements and other assets 112,841 129,895 242,736  Above market leases (a) 350 - 350  In-place lease values (a) 4,585 4,913 9,498  Less: Below market lease values (a) (141) (118) (259)  144,935 166,151 311,086  Less: Debt assumed at fair value (79,544) (91,656) (171,200)  Net assets recorded upon consolidation $ 65,391 $ 74,495 $ 139,886  (a) Above market, in-place and below market leases are being amortized over a weighted-average term of 8 months.  2016 On January 5, 2016, the Company, which held a 50 percent subordinated interest in the unconsolidated joint venture, Overlook Ridge Apartment Investors LLC, a 371 -unit multi-family operating property located in Malden, Massachusetts, acquired the remaining interest for $39.8 million in cash plus the assumption of a first mortgage loan secured by the property with a principal balance of $52.7 million. The cash portion of the acquisition was funded primarily through borrowings under the Company’s unsecured revolving credit facility. Upon acquisition, the Company consolidated the asset and accordingly, remeasured its equity interests, as required by the FASB’s consolidation guidance, at fair value (based upon the income approach using current rates and market cap rates and discount rates). As a result, the Company recorded a gain on change of control of interests of $10.2 million in the year ended December 31, 2016. On January 19, 2016, the Company repaid the assumed loan and obtained a new loan secured by the property in the amount of $72.5 million, which bears interest at 3.625 percent and matures in February 2023 . See Note 9: Mortgages, Loans Payable and Other Obligations.  During the second quarter 2016, the Company, which held a 38.25 percent subordinate interest in the unconsolidated Portside Apartment Developers, L.L.C., a joint venture which owns a 175 -unit operating multi-family property located in East Boston, Massachusetts, acquired the remaining interests of its joint venture partners for $39.6 million in cash plus the assumption of a mortgage loan secured by the property with a principal balance of $42.5 million. The cash portion of the acquisition was funded primarily through borrowings under the Company’s unsecured revolving credit facility. Upon acquisition, the Company consolidated the asset and accordingly, remeasured its equity interests, as required by the FASB’s consolidation guidance, at fair value (based upon the income approach using current rates and market cap rates and discount rates). As a result, the Company recorded a gain on change of control of interests of $5.2 million in the year ended December 31, 2016. On July 8, 2016, the Company repaid the assumed loan and obtained a new loan secured by the property in the amount of $59 million, which bears interest at 3.44 percent and matures in August 2023 . See Note 9: Mortgages, Loans Payable and Other Obligations.  The purchase prices were preliminarily allocated to the net assets acquired upon consolidation, as follows (in thousands) :     Overlook Portside  Ridge Apts  Land and leasehold interest $ 11,072 $ -  Buildings and improvements 87,793 73,713  Furniture, fixtures and equipment 1,695 1,038  Other assets 237 10,181  In-place lease values (a) 4,389 2,637  Less: Below market lease values (a) (489) (242)  Sub Total 104,697 87,327   Less: Debt assumed (52,662) (42,500)   Net assets recorded upon consolidation $ 52,035 $ 44,827  (a) In-place lease values and below-market lease values are be ing amortized over a weighted average term of 7.4 months .  Other Investments in 2016 On April 26, 2016, the Company acquired the remaining non-controlling interest in a development project located in Weehawken, New Jersey for $36.4 million. The project includes developable land for approximately 1,100 multi-family units, 290,000 square feet of office space, a 52.5 percent ownership interest in Port Imperial 4/5 Garage and Retail operating properties. The initial phase, Port Imperial South 11, a 295 -unit multi-family project, began construction in the first quarter 2016.  Dispositions /Rental Property Held for Sale  201 7 The Company disposed of the following office properties during the year ended December 31, 201 7 (dollars in thousands) :     Realized  Gains  Rentable Net Net (losses)/  Disposition # of Square Sales Carrying Unrealized  Date Property/Address Location Bldgs. Feet Proceeds Value Losses, net  01/30/17 Cranford portfolio Cranford, New Jersey 6 435,976 $ 26,598 $ 22,736 $ 3,862  01/31/17 440 Route 22 East (a) Bridgewater, New Jersey 1 198,376 10,074 10,069 5  02/07/17 3 Independence Way Princeton, New Jersey 1 111,300 11,549 9,910 1,639  05/15/17 103 Carnegie Center Princeton, New Jersey 1 96,000 15,063 8,271 6,792  08/29/17 400 Chestnut Ridge Road Woodcliff Lake, New Jersey 1 89,200 6,891 7,498 (607)  08/30/17 140 E. Ridgewood Avenue Paramus, New Jersey 1 239,680 30,201 30,737 (536)  08/30/17 Bergen portfolio Woodcliff Lake, Paramus and 5 1,061,544 86,973 (c) 135,121 (48,148)  Rochelle Park, New Jersey  09/11/17 377 Summerhill Road East Brunswick, New Jersey 1 40,000 3,221 2,172 1,049  09/13/17 700 Executive Boulevard Elmsford, New York - - (b) 5,717 970 4,747  09/20/17 Totowa Portfolio Totowa, New Jersey 13 499,243 63,624 27,630 35,994  09/27/17 890 Mountain Avenue (d) New Providence, New Jersey 1 80,000 4,852 6,139 (1,287)  09/28/17 135 Chestnut Ridge Road Montvale, New Jersey 1 66,150 5,844 (e) 2,929 2,915  09/29/17 Moorestown portfolio Moorestown and Burlington, New Jersey 26 1,260,398 73,393 (f) 56,186 17,207  10/19/17 1 Enterprise Boulevard Yonkers, New York - - (b) 3,230 1,380 1,850  11/15/17 61 South Paramus Road Paramus, New Jersey 1 269,191 23,255 37,184 (13,929)  12/06/17 300 Tice Boulevard Woodcliff Lake, New Jersey 1 230,000 28,847 25,705 3,142  Sub-total 60 4,677,058 399,332 384,637 14,695   Unrealized losses on rental property held for sale (12,331)   Totals 60 4,677,058 $ 399,332 $ 384,637 $ 2,364   (a) The Company recorded a valuation allowance of $7.7 million on this property during the year ended December 31, 2016.  (b) This disposition is of a ground leased land property.  (c) At closing, the Company provided short term seller financing aggregating $65 million through mortgage notes receivable to the buyers. These notes were paid off in November  and December 2017.  (d) The Company recorded an impairment charge of $7.0 million on this property during the year ended December 31, 2015.  (e) The Company recorded an impairment charge of $4.2 million on this property during the year ended December 31, 2015. $5.9 million of the sales proceeds from this sale were  held by a qualified intermediary, which is noncash and recorded in deferred charges, goodwill and other assets as of December 31, 2017. See Note 5: Deferred Charges,  Goodwill and Other Assets, Net.  (f) $15.3 million of the sales proceeds from this sale were held by a qualified intermediary, which is noncash and recorded in deferred charges, goodwill and other assets  as of December 31, 2017. See Note 5: Deferred Charges, Goodwill and Other Assets, Net.   The Company identified as held for sale 21 office properties totaling approximately 2 million square feet as of December 31, 2017. The properties are located in Parsippany, Paramus, Rochelle Park, Hamilton and Wall, New Jersey and White Plains, New York. The total estimated sales proceeds from the sales are expected to be approximately $223 million. The Company determined that the carrying value of seven of the office properties was not expected to be recovered from estimated net sales proceeds and accordingly recognized an unrealized loss allowance of $12.3 million during the year ended December 31, 2017. In February 2018, the Company completed the disposition of one of these properties for sales proceeds of $25.9 million.  The following table summarizes the rental property held for sale, net, as of December 31, 2017: (dollars in thousands)     December 31,  2017  Land $ 37,024  Buildings and improvements 273,388  Less: Accumulated depreciation (126,503)  Less: Unrealized losses on properties held for sale (12,331)  Rental property held for sale,net $ 171,578   Other assets and liabilities related to the rental properties held for sale, as of December 31, 2017, include $9.8 million in deferred charges, and other assets, $4.7 million in Unbilled rents receivable and $ 4.6 million in Accounts payable, accrued expenses and other liabilities. Approximately $13.4 million of these assets and $ 0.3 million of these liabilities are expected to be written off with the completion of the sales.  2016 The Company disposed of the following office and multi-family properties during the year ended December 31, 201 6 (dollars in thousands) :     Realized  Gains  Net Net (losses)/  Disposition # of Sales Carrying Unrealized  Date Property/Address Location Bldgs. Proceeds Value Losses, net  03/11/16 2 Independence Way (a) Princeton, New Jersey 1 $ 4,119 $ 4,283 $ (164)  03/24/16 1201 Connecticut Avenue, NW Washington, D.C. 1 90,591 31,827 58,764  04/26/16 125 Broad Street (b) New York, New York 1 192,323 200,183 (7,860)  05/09/16 9200 Edmonston Road Greenbelt, Maryland 1 4,083 (c) 3,837 246  05/18/16 1400 L Street Washington, D.C. 1 68,399 30,053 38,346  07/14/16 600 Parsippany Road Parsippany, New Jersey 1 10,465 (d) 5,875 4,590  07/14/16 4,5,6 Century Drive (e) Parsippany, New Jersey 3 14,533 17,308 (2,775)  08/11/16 Andover Place Andover, Massachusetts 1 39,863 37,150 2,713  09/26/16 222,233 Mount Airy Road (f) Basking Ridge, New Jersey 2 8,817 9,039 (222)  09/27/16 10 Mountainview Road Upper Saddle River, New Jersey 1 18,990 19,571 (581)  11/07/16 100 Willowbrook, 2,3,4 Paragon (g) Freehold, New Jersey 4 14,634 19,377 (4,743)  12/05/16 4 Becker Farm Road Roseland, New Jersey 1 41,400 (h) 31,001 10,399  12/09/16 101,103,105 Eisenhower Parkway Roseland, New Jersey 3 46,423 45,999 424  12/22/16 Capital Office Park, Ivy Lane (i) Greenbelt, Maryland 6 46,570 65,064 (18,494)  12/22/16 100 Walnut Avenue Clark, New Jersey 1 28,428 7,529 20,899  12/22/16 20 Commerce Drive Cranford, New Jersey 1 28,878 13,071 15,807  12/29/16 4200 Parliament Place (j) Lanham, Maryland 1 5,965 5,983 (18)  Sub-total 30 664,481 547,150 117,331   Unrealized losses on rental property held for sale (7,665)   Totals 30 $ 664,481 $ 547,150 $ 109,666   (a) The Company recorded an impairment charge of $3.2 million on this property during the year ended December 31, 2015.  (b) The Company recorded impairment charges of $83.2 million on this property during the year ended December 31, 2015.  (c) The Company transferred the deed for this property to the lender in satisfaction of its obligations. The Company recorded an impairment charge of $3.0 million  on this property during the year ended December 31, 2012.  (d) $10.5 million of the net sales proceeds from this sale were held by a qualified intermediary. The Company received these proceeds on January 11, 2017.  (e) The Company recorded impairment charges of $9.8 million on these properties during the year ended December 31, 2015.  (f) The Company recorded impairment charges of $1.0 million on these properties during the year ended December 31, 2015.  (g) The Company recorded impairment charges of $7.4 million on these properties during the year ended December 31, 2015.  (h) The Company transferred the deed for this property to the lender in satisfaction of its obligations.  (i) The Company recorded impairment charges of $66.5 million on these properties during the year ended December 31, 2015.  (j) The Company recorded an impairment charge of $4.2 million on this property during the year ended December 31, 2015.  As of December 31, 2016, the Company identified as held for sale eight office properties totaling approximately 750,000 square feet. The properties were located in Princeton, Cranford and Bridgewater, New Jersey. The Company determined that the carrying value of one of the office properties was not expected to be recovered from estimated net sales proceeds and accordingly recognized an unrealized loss allowance of $7.7 million at December 31, 2016. In January and February 2017, the Company completed the disposition of these properties for sales proceeds of approximately $45.8 million.  The following table summarizes the rental property held for sale, net, as of December 31, 2016: (dollars in thousands)     December 31,  2016  Land $ 10,934  Buildings and improvements 68,266  Less: Accumulated depreciation (31,792)  Less: Unrealized losses on properties held for sale (7,665)  Rental property held for sale,net $ 39,743  Other assets and liabilities related to the rental properties held for sale, as of December 31, 2016, include $1.7 million in deferred charges, and other assets, $1.2 million in Unbilled rents receivable, $ 1.1 million in Accounts payable, accrued expenses and other liabilities, and $1.9 million in Rents received in advance and security deposits. Approximately $2.9 million of these assets and $ 0.5 million of these liabilities are expected to be written off with the completion of the sales.  Rockpoint Transaction On February 27, 2017, the Company, Roseland Residential Trust (“RRT”), the Company’s wholly-owned subsidiary through which the Company conducts its multi-family residential real estate operations, Roseland Residential, L.P. (“RRLP”), the operating partnership through which RRT conducts all of its operations, and certain other affiliates of the Company entered into an equity investment agreement (the “Investment Agreement”) with Rockpoint Group, L.L.C. and certain of its affiliates (collectively, “Rockpoint”). The Investment Agreement provides for multiple equity investments by Rockpoint in RRLP from time to time for up to an aggregate of $300 million of equity units of limited partnership interests of RRLP (the “Rockpoint Units”). The initial closing under the Investment Agreement occurred on March 10, 2017 for $150 million of Rockpoint Units. Additional closings of Rockpoint Units to be issued and sold to Rockpoint pursuant to the Investment Agreement may occur from time to time in increments of not less than $10 million per closing, with the balance of the full $300 million by March 1, 2019. See Note 14: Redeemable Noncontrolling Interests.  RRLP has been identified as a variable interest entity in which the Company is deemed to be the primary beneficiary. As of December 31, 2017 and December 31, 2016, the Company’s consolidated RRLP entity had total assets of $1.9 billion and $1.3 billion, respectively, total mortgages and loan payable of $769.7 million and $480.7 million, respectively, and other liabilities of $95.9 million and $40.1 million, respectively.  Unconsolidated Joint Venture Activity On April 1, 2016, the Company bought out its partner PruRose Riverwalk G, L.L.C. for $11.3 million and increased its subordinated interest in Riverwalk G Urban Renewal, L.L.C. from 25 percent to 50 percent using borrowings on the Company’s unsecured credit facility. Riverwalk G Urban Renewal, L.L.C., owns a 316 -unit operating multi-family property located in West New York, New Jersey. Concurrent with the refinancing in October 2016, the Company executed an agreement with the remaining partner which converted the 50 percent subordinated interest to 22.5 percent pari passu interest.  On May 26, 2016, the Company sold its 50 percent interest in Port Imperial South 15, L.L.C. (“RiversEdge”) and its 20 percent interest in Port Imperial South 13 Urban Renewal, L.L.C. (“RiverParc”), joint ventures that own the 236 -unit and the 280 -unit multi-family operating properties, respectively, located in Weehawken, New Jersey for $6.4 million. The Company realized a gain on the sale of $5.7 million.  On January 31 , 2017, the Company sold its interest in the KPG-P 100 IMW JV, LLC, Keystone-Penn and Keystone-Tristate joint ventures that own operating properties, located in Philadelphia, Pennsylvania for a n aggregate sales price of $9.7 million and realized a gain on the sale of the unconsolidated joint venture of $7.4 million.  On February 15, 2017, the Company sold its 7.5 percent interest in the Elmajo Urban Renewal Associates, LLC and Estuary Urban Renewal Unit B, LLC joint ventures that own operating multi-family properties located in Weehawken, New Jersey for a sales price of $5.1 million and realized a gain on the sale of the unconsolidated joint venture of $5.1 million.  On September 21, 2017, the RoseGarden Monaco, L.L.C. joint venture agreement was terminated. Accordingly, the Company wrote off the carrying value of its investment in the joint venture and recorded a loss of $1.4 million on the disposition of its joint venture interest.  On September 29, 2017, the Company sold its interests in the KPG-MCG Curtis joint venture that owns an operating property located in Philadelphia, Pennsylvania for a sales price of $102.5 million, which included the retirement of the Company’s share in a mortgage payable of $75 million, and realized a gain on the sale of the unconsolidated joint venture of $12 million. $5.6 million of the net sales proceeds from this sale were held by a qualified intermediary, which is considered non cash and recorded in deferred charges, goodwill and other assets. See Note 5: Deferred Charges, Goodwill and Other Assets, Net.

Investments In Unconsolidated J

Investments In Unconsolidated Joint Ventures	12 Months Ended
	Dec. 31, 2017
Investments In Unconsolidated Joint Ventures [Line Items]
Investments In Unconsolidated Joint Ventures	4. INVESTMENTS IN UNCONSOLIDATED JOINT VENTURES  As of December 31, 2017 , the Company had an aggregate investment of approximately $252.6 million in its equity method joint ventures. The Company formed these ventures with unaffiliated third parties, or acquired interests in them, to develop or manage primarily office and multi-family rental properties, or to acquire land in anticipation of possible development of office and multi-family rental properties. As of December 31, 2017 , the unconsolidated joint ventures owned: four office properties aggregating approximately 0.5 million square feet, eight multi-family properties totaling 3,275 apartments, two retail properties aggregating approximately 81,700 square feet, a 350 -room hotel, development project s for up to approximately 419 apartments; and interests and/or rights to developable land parcels able to accommodate up to 3,738 apartments. The Company’s unconsolidated interests range from 12.5 percent to 85 percent subject to specified priority allocations in certain of the joint ventures.  The amounts reflected in the following tables (except for the Company’s share of equity in earnings) are based on the historical financial information of the individual joint ventures. The Company does not record losses of the joint ventures in excess of its investment balances unless the Company is liable for the obligations of the joint venture or is otherwise committed to provide financial support to the joint venture. The outside basis portion of the Company’s investments in joint ventures is amortized over the anticipated useful lives of the underlying ventures’ tangible and intangible assets acquired and liabilities assumed. Unless otherwise noted below, the debt of the Company’s unconsolidated joint ventures generally is non-recourse to the Company, except for customary exceptions pertaining to such matters as intentional misuse of funds, environmental conditions, and material misrepresentations.  The Company has agreed to guarantee repayment of a portion of the debt of its unconsolidated joint ventures. As of December 31, 2017 , such debt had a total facility amount of $318 million of which the Company agreed to guarantee up to $36 million. As of December 31, 2017 , the outstanding balance of such debt totaled $200.1 million of which $24 million was guaranteed by the Company. The Company performed management, leasing, development and other services for the properties owned by the unconsolidated joint ventures and recognized $2.8 million and $3.7 million for such services in the years ended December 31, 2017 and 2016 , respectively. The Company had $ 0.8 million and $0.7 million in accounts receivable due from its unconsolidated joint ventures as of December 31, 2017 and 2016 .  Included in the Company’s investments in unconsolidated joint ventures as of December 31, 2017 are four unconsolidated development joint ventures, which are VIEs for which the Company is not the primary beneficiary. These joint ventures are primarily established to develop real estate property for long-term investment and were deemed VIEs primarily based on the fact that the equity investment at risk was not sufficient to permit the entities to finance their activities without additional financial support. The initial equity contributed to these entities was not sufficient to fully finance the real estate construction as development costs are funded by the partners throughout the construction period. The Company determined that it was not the primary beneficiary of these VIEs based on the fact that the Company has shared control of these entities along with the entity’s partners and therefore does not have controlling financial interests in these VIEs. The Company’s aggregate investment in these VIEs was approximately $ 129.5 million as of December 31, 2017 . The Company’s maximum exposure to loss as a result of its involvement with these VIEs is estimated to be approximately $ 165.5 million, which includes the Company’s current investment and estimated future funding commitments/guarantees of approximately $ 36.0 million. The Company has not provided financial support to these VIEs that it was not previously contractually required to provide. In general, future costs of development not financed through third parties will be funded with capital contributions from the Company and its outside partners in accordance with their respective ownership percentages.      The following is a summary of the Company's unconsolidated joint ventures as of December 31, 2017 and 2016 : (dollars in thousands)   Property Debt  Number of Company's Carrying Value As of December 31, 2017  Apartment Units Effective December 31, December 31, Maturity Interest  Entity / Property Name or Rentable Square Feet (sf) Ownership % (a) 2017 2016 Balance Date Rate  Multi-family  Marbella RoseGarden, L.L.C./ Marbella 412 units 24.27 % $ 14,544 $ 15,150 $ 95,000 05/01/18 4.99 %  RoseGarden Monaco Holdings, L.L.C./ Monaco 523 units (e) - - - - -  Rosewood Morristown, L.L.C. / Metropolitan at 40 Park (b) (c) 130 units 12.50 % 6,834 7,145 53,224 (d) (d)  Riverwalk G Urban Renewal, L.L.C./ RiverTrace at Port Imperial 316 units 22.50 % 8,864 9,707 82,000 11/10/26 3.21 %  Elmajo Urban Renewal Associates, LLC / Lincoln Harbor (Bldg A&C) (f) 355 units 7.50 % - - - - -  Crystal House Apartments Investors LLC / Crystal House (g) 825 units 25.00 % 30,570 30,565 165,000 04/01/20 3.17 %  Riverwalk C Urban Renewal, L.L.C. (h) 360 units 40.00 % 16,844 - - 12/06/21 L+2.75 %  RoseGarden Marbella South, L.L.C./ Marbella II 311 units 24.27 % 16,471 18,050 74,690 03/30/18 L+2.25 % (i)  Estuary Urban Renewal Unit B, LLC / Lincoln Harbor (Bldg B) (f) 227 units 7.50 % - - - - -  Riverpark at Harrison I, L.L.C./ Riverpark at Harrison 141 units 45.00 % 1,604 2,085 30,000 08/01/25 3.70 %  Capitol Place Mezz LLC / Station Townhouses 378 units 50.00 % 40,124 43,073 100,070 07/01/33 4.82 %  Harborside Unit A Urban Renewal, L.L.C. / URL Harborside 762 units 85.00 % 94,429 100,188 189,853 08/01/29 5.197 % (j)  Roseland/Port Imperial Partners, L.P. (k) 836 potential units 20.00 % 1,678 1,678 - - -  RoseGarden Monaco, L.L.C./ San Remo Land (l) 250 potential units 41.67 % - 1,400 - - -  Grand Jersey Waterfront URA, L.L.C./ Liberty Landing 850 potential units 50.00 % 337 337 - - -  Hillsborough 206 Holdings, L.L.C./ Hillsborough 206 160,000 sf 50.00 % 1,962 1,962 - - -  Plaza VIII & IX Associates, L.L.C./ Vacant land (parking operations) (m) 1,225,000 sf 50.00 % - 4,448 - - -   Office  Red Bank Corporate Plaza, L.L.C./ Red Bank 92,878 sf 50.00 % 4,602 4,339 13,876 05/17/18 L+3.00 %  12 Vreeland Associates, L.L.C./ 12 Vreeland Road 139,750 sf 50.00 % 6,734 6,237 9,495 07/01/23 2.87 %  BNES Associates III / Offices at Crystal Lake 106,345 sf 31.25 % 3,369 3,124 4,794 11/01/23 4.76 %  KPG-P 100 IMW JV, LLC / 100 Independence Mall West 339,615 sf (n) - - - - -  Keystone-Penn 1,842,820 sf (n) - - - - -  Keystone-TriState 1,266,384 sf (n) - 2,285 - - -  KPG-MCG Curtis JV, L.L.C./ Curtis Center 885,000 sf (o) - 65,400 - - -   Other  Roseland/North Retail, L.L.C./ Riverwalk at Port Imperial 30,745 sf 20.00 % 1,625 1,706 - - -  South Pier at Harborside / Hyatt Regency Jersey City on the Hudson 350 rooms 50.00 % 440 163 99,135 10/01/26 3.668 %  Other (p) 1,595 1,005 - - -  Totals: $ 252,626 $ 320,047 $ 917,137     (a) Company's effective ownership % represents the Company's entitlement to residual distributions after payments of priority returns, where applicable.  (b) The Company's ownership interests in this venture are subordinate to its partner's preferred capital balance and the Company is not expected to meaningfully participate in the venture's cash flows in the near term.  (c) Through the joint venture, the Company also owns a 12.5 percent interest in a 50,973 square feet retail building ("Shops at 40 Park") and a 25 percent interest in a to-be-built 59 -unit, five story multi-family rental development property ("Lofts at 40 Park").  (d) Property debt balance consists of: (i) an amortizable loan, collateralized by the Metropolitan at 40 Park, with a balance of $36.8 million bears interest at 3.25 percent, matures in September 2020 ; (ii) an amortizable loan, collateralized by the Shops at 40 Park, with a balance of $6.2 million, bears interest at 3.63 percent, matures in August 2018 . On February 3, 2017, the venture obtained a construction loan for the Lofts at 40 Park with a balance of $10.2 million, which bears interest at LIBOR plus 250 basis points and matures in February 2020 and provides, subject to certain conditions, two one -year extension options with a fee of 15 basis points for each year.  (e) On February 28, 2017, 9,122 Series A-1 Units were issued to the joint venture partner as noncash consideration for the partner's approximate 13.8 percent ownership interest in the joint venture. In April 2017, the Company acquired the remaining joint venture interests and increased its ownership interest to 100 percent. See Note 3: Recent Transactions – Consolidation.  (f) On February 15, 2017, the Company sold its 7.5 percent interest in Elmajo Urban Renewal Associates, LLC and Estuary Urban Renewal Unit B, LLC joint ventures that own operating multi-family properties, located in Weehawken, New Jersey for a combined sales price of $5.1 million.  (g) The Company also owns a 50 percent interest in a vacant land to accommodate the development of approximately 295 additional units of which 252 are currently approved.  (h) On December 7, 2017, simultaneous with the financing of the construction loan, the Company converted its 20 percent subordinate interest to 40 percent pari-passu interest.  (i) The construction loan had a maximum borrowing amount of $77.4 million and provided, subject to certain conditions, two one -year extension options with a fee of 25 basis points for each year. On March 31, 2017, the Company exercised its first one -year extension option and concurrently the maximum borrowing amount was reduced to $75 million.  (j) The construction/permanent loan has a maximum borrowing amount of $192 million. The Company owns an 85 percent interest with shared control over major decisions such as, approval of budgets, property financings and leasing guidelines. The development project was placed in service in second quarter 2017.  (k) The Company also owns a 20 percent residual interest in undeveloped land parcels: parcels 6, I, and J that can accommodate the development of 836 apartment units.  (l) On September 21, 2017, the joint venture agreement was terminated. Accordingly, the Company wrote off the carrying value of its investment in the joint venture and recorded a loss of $1.4 million on the disposition of its joint venture interest.  (m) On February 3, 2017, the Company acquired the equity interest of its partner. See Note 3: Recent Transactions - Consolidation.  (n) On January 31, 2017, the Company sold its equity interest in the joint venture. See Note 3: Recent Transactions - Unconsolidated Joint Venture Activity.  (o) Includes undivided interests in the same manner as investments in noncontrolling partnership, pursuant to ASC 970-323-25-12. On September 29, 2017, the Company sold its equity interest to its joint venture partner, which included the retirement of the Company's share in the debt of $75 million. See Note 3: Recent Transactions - Unconsolidated Joint Venture Activity.  (p) The Company owns other interests in various unconsolidated joint ventures, including interests in assets previously owned and interest in ventures whose businesses are related to its core operations. These ventures are not expected to significantly impact the Company's operations in the near term. The following is a summary of the Compan y’s equity in earnings (loss) of unconsolidated joint ventures for the years ended December 31, 2017 , 2016 and 2015: (dollars in thousands)     Year Ended December 31,  Entity / Property Name 2017 2016 2015  Multi-family  Marbella RoseGarden, L.L.C./ Marbella $ 334 $ 231 $ 231  RoseGarden Monaco Holdings, L.L.C./ Monaco (265) (937) (1,224)  Rosewood Morristown, L.L.C. / Metropolitan at 40 Park (311) (317) (364)  Riverwalk G Urban Renewal, L.L.C./ RiverTrace at Port Imperial 196 (1,146) (955)  Crystal House Apartments Investors LLC / Crystal House (923) (870) (123)  Riverwalk C Urban Renewal, L.L.C. (653) (58) (306)  RoseGarden Marbella South, L.L.C./ Marbella II 93 (202) -  Estuary Urban Renewal Unit B, LLC / Lincoln Harbor (Bldg B) - - 1  Riverpark at Harrison I, L.L.C./ Riverpark at Harrison (252) (190) (363)  Capitol Place Mezz LLC / Station Townhouses (1,793) (2,440) (3,687)  Harborside Unit A Urban Renewal, L.L.C. / URL Harborside (6,356) (219) -  Roseland/Port Imperial Partners, L.P. (219) (62) (168)  Grand Jersey Waterfront URA, L.L.C./ Liberty Landing (15) (80) (32)  Hillsborough 206 Holdings, L.L.C./ Hillsborough 206 (25) (53) (5)  Plaza VIII & IX Associates, L.L.C./ Vacant land (parking operations) 386 393 344  Office  Red Bank Corporate Plaza, L.L.C./ Red Bank 238 448 392  12 Vreeland Associates, L.L.C./ 12 Vreeland Road 496 347 270  BNES Associates III / Offices at Crystal Lake 89 (15) 115  KPG-P 100 IMW JV, LLC / 100 Independence Mall West - - (800)  Keystone-Penn - 600 3,812  Keystone-TriState - (1,672) (2,182)  KPG-MCG Curtis JV, L.L.C./ Curtis Center (436) (92) 475  Other  Roseland/North Retail, L.L.C./ Riverwalk at Port Imperial (81) (52) (70)  South Pier at Harborside / Hyatt Regency Jersey City on the Hudson (a) 3,277 24,180 3,036  Other 139 994 (1,569)  Company's equity in earnings (loss) of unconsolidated joint ventures (b) $ (6,081) $ 18,788 $ (3,172) (a) Equity in earnings in 2016 includes the effect of distributions received from the joint venture’s refinancing. See Recent Joint Venture Transactions following in this footnote. (b) Amounts are net of amortization of basis differences of $792 , $436 and $336 for the years ended December 31, 2017, 2016 and 2015, respectively.  The following is a summary of the combined financial position of the unconsolidated joint ventures in which the Company had investment interests as of December 31, 2017 and 2016 : (dollars in thousands)     December 31, December 31,  2017 2016  Assets:  Rental property, net $ 931,419 $ 1,746,233  Other assets 207,903 278,289  Total assets $ 1,139,322 $ 2,024,522  Liabilities and partners'/  members' capital:  Mortgages and loans payable $ 689,412 $ 1,350,973  Other liabilities 80,746 247,212  Partners'/members' capital 369,164 426,337  Total liabilities and  partners'/members' capital $ 1,139,322 $ 2,024,522   The following is a summary of the combined results from operations of the unconsolidated joint ventures for the period in which the Company had investment interests during the year s ended December 31, 2017 , 2016 and 2015 : (dollars in thousands)     Year Ended December 31,  2017 2016 2015  Total revenues $ 358,751 $ 377,711 $ 318,980  Operating and other expenses (297,492) (262,703) (220,982)  Depreciation and amortization (31,020) (75,512) (71,711)  Interest expense (25,822) (58,390) (52,972)  Net income (loss) $ 4,417 $ (18,894) $ (26,685) 
Mack-Cali Realty LP [Member]
Investments In Unconsolidated Joint Ventures [Line Items]
Investments In Unconsolidated Joint Ventures	4. INVESTMENTS IN UNCONSOLIDATED JOINT VENTURES  As of December 31, 2017 , the Company had an aggregate investment of approximately $252.6 million in its equity method joint ventures. The Company formed these ventures with unaffiliated third parties, or acquired interests in them, to develop or manage primarily office and multi-family rental properties, or to acquire land in anticipation of possible development of office and multi-family rental properties. As of December 31, 2017 , the unconsolidated joint ventures owned: four office properties aggregating approximately 0.5 million square feet, eight multi-family properties totaling 3,275 apartments, two retail properties aggregating approximately 81,700 square feet, a 350 -room hotel, development project s for up to approximately 419 apartments; and interests and/or rights to developable land parcels able to accommodate up to 3,738 apartments. The Company’s unconsolidated interests range from 12.5 percent to 85 percent subject to specified priority allocations in certain of the joint ventures.  The amounts reflected in the following tables (except for the Company’s share of equity in earnings) are based on the historical financial information of the individual joint ventures. The Company does not record losses of the joint ventures in excess of its investment balances unless the Company is liable for the obligations of the joint venture or is otherwise committed to provide financial support to the joint venture. The outside basis portion of the Company’s investments in joint ventures is amortized over the anticipated useful lives of the underlying ventures’ tangible and intangible assets acquired and liabilities assumed. Unless otherwise noted below, the debt of the Company’s unconsolidated joint ventures generally is non-recourse to the Company, except for customary exceptions pertaining to such matters as intentional misuse of funds, environmental conditions, and material misrepresentations.  The Company has agreed to guarantee repayment of a portion of the debt of its unconsolidated joint ventures. As of December 31, 2017 , such debt had a total facility amount of $318 million of which the Company agreed to guarantee up to $36 million. As of December 31, 2017 , the outstanding balance of such debt totaled $200.1 million of which $24 million was guaranteed by the Company. The Company performed management, leasing, development and other services for the properties owned by the unconsolidated joint ventures and recognized $2.8 million and $3.7 million for such services in the years ended December 31, 2017 and 2016 , respectively. The Company had $ 0.8 million and $0.7 million in accounts receivable due from its unconsolidated joint ventures as of December 31, 2017 and 2016 .  Included in the Company’s investments in unconsolidated joint ventures as of December 31, 2017 are four unconsolidated development joint ventures, which are VIEs for which the Company is not the primary beneficiary. These joint ventures are primarily established to develop real estate property for long-term investment and were deemed VIEs primarily based on the fact that the equity investment at risk was not sufficient to permit the entities to finance their activities without additional financial support. The initial equity contributed to these entities was not sufficient to fully finance the real estate construction as development costs are funded by the partners throughout the construction period. The Company determined that it was not the primary beneficiary of these VIEs based on the fact that the Company has shared control of these entities along with the entity’s partners and therefore does not have controlling financial interests in these VIEs. The Company’s aggregate investment in these VIEs was approximately $ 129.5 million as of December 31, 2017 . The Company’s maximum exposure to loss as a result of its involvement with these VIEs is estimated to be approximately $ 165.5 million, which includes the Company’s current investment and estimated future funding commitments/guarantees of approximately $ 36.0 million. The Company has not provided financial support to these VIEs that it was not previously contractually required to provide. In general, future costs of development not financed through third parties will be funded with capital contributions from the Company and its outside partners in accordance with their respective ownership percentages.      The following is a summary of the Company's unconsolidated joint ventures as of December 31, 2017 and 2016 : (dollars in thousands)   Property Debt  Number of Company's Carrying Value As of December 31, 2017  Apartment Units Effective December 31, December 31, Maturity Interest  Entity / Property Name or Rentable Square Feet (sf) Ownership % (a) 2017 2016 Balance Date Rate  Multi-family  Marbella RoseGarden, L.L.C./ Marbella 412 units 24.27 % $ 14,544 $ 15,150 $ 95,000 05/01/18 4.99 %  RoseGarden Monaco Holdings, L.L.C./ Monaco 523 units (e) - - - - -  Rosewood Morristown, L.L.C. / Metropolitan at 40 Park (b) (c) 130 units 12.50 % 6,834 7,145 53,224 (d) (d)  Riverwalk G Urban Renewal, L.L.C./ RiverTrace at Port Imperial 316 units 22.50 % 8,864 9,707 82,000 11/10/26 3.21 %  Elmajo Urban Renewal Associates, LLC / Lincoln Harbor (Bldg A&C) (f) 355 units 7.50 % - - - - -  Crystal House Apartments Investors LLC / Crystal House (g) 825 units 25.00 % 30,570 30,565 165,000 04/01/20 3.17 %  Riverwalk C Urban Renewal, L.L.C. (h) 360 units 40.00 % 16,844 - - 12/06/21 L+2.75 %  RoseGarden Marbella South, L.L.C./ Marbella II 311 units 24.27 % 16,471 18,050 74,690 03/30/18 L+2.25 % (i)  Estuary Urban Renewal Unit B, LLC / Lincoln Harbor (Bldg B) (f) 227 units 7.50 % - - - - -  Riverpark at Harrison I, L.L.C./ Riverpark at Harrison 141 units 45.00 % 1,604 2,085 30,000 08/01/25 3.70 %  Capitol Place Mezz LLC / Station Townhouses 378 units 50.00 % 40,124 43,073 100,070 07/01/33 4.82 %  Harborside Unit A Urban Renewal, L.L.C. / URL Harborside 762 units 85.00 % 94,429 100,188 189,853 08/01/29 5.197 % (j)  Roseland/Port Imperial Partners, L.P. (k) 836 potential units 20.00 % 1,678 1,678 - - -  RoseGarden Monaco, L.L.C./ San Remo Land (l) 250 potential units 41.67 % - 1,400 - - -  Grand Jersey Waterfront URA, L.L.C./ Liberty Landing 850 potential units 50.00 % 337 337 - - -  Hillsborough 206 Holdings, L.L.C./ Hillsborough 206 160,000 sf 50.00 % 1,962 1,962 - - -  Plaza VIII & IX Associates, L.L.C./ Vacant land (parking operations) (m) 1,225,000 sf 50.00 % - 4,448 - - -   Office  Red Bank Corporate Plaza, L.L.C./ Red Bank 92,878 sf 50.00 % 4,602 4,339 13,876 05/17/18 L+3.00 %  12 Vreeland Associates, L.L.C./ 12 Vreeland Road 139,750 sf 50.00 % 6,734 6,237 9,495 07/01/23 2.87 %  BNES Associates III / Offices at Crystal Lake 106,345 sf 31.25 % 3,369 3,124 4,794 11/01/23 4.76 %  KPG-P 100 IMW JV, LLC / 100 Independence Mall West 339,615 sf (n) - - - - -  Keystone-Penn 1,842,820 sf (n) - - - - -  Keystone-TriState 1,266,384 sf (n) - 2,285 - - -  KPG-MCG Curtis JV, L.L.C./ Curtis Center 885,000 sf (o) - 65,400 - - -   Other  Roseland/North Retail, L.L.C./ Riverwalk at Port Imperial 30,745 sf 20.00 % 1,625 1,706 - - -  South Pier at Harborside / Hyatt Regency Jersey City on the Hudson 350 rooms 50.00 % 440 163 99,135 10/01/26 3.668 %  Other (p) 1,595 1,005 - - -  Totals: $ 252,626 $ 320,047 $ 917,137     (a) Company's effective ownership % represents the Company's entitlement to residual distributions after payments of priority returns, where applicable.  (b) The Company's ownership interests in this venture are subordinate to its partner's preferred capital balance and the Company is not expected to meaningfully participate in the venture's cash flows in the near term.  (c) Through the joint venture, the Company also owns a 12.5 percent interest in a 50,973 square feet retail building ("Shops at 40 Park") and a 25 percent interest in a to-be-built 59 -unit, five story multi-family rental development property ("Lofts at 40 Park").  (d) Property debt balance consists of: (i) an amortizable loan, collateralized by the Metropolitan at 40 Park, with a balance of $36.8 million bears interest at 3.25 percent, matures in September 2020 ; (ii) an amortizable loan, collateralized by the Shops at 40 Park, with a balance of $6.2 million, bears interest at 3.63 percent, matures in August 2018 . On February 3, 2017, the venture obtained a construction loan for the Lofts at 40 Park with a balance of $10.2 million, which bears interest at LIBOR plus 250 basis points and matures in February 2020 and provides, subject to certain conditions, two one -year extension options with a fee of 15 basis points for each year.  (e) On February 28, 2017, 9,122 Series A-1 Units were issued to the joint venture partner as noncash consideration for the partner's approximate 13.8 percent ownership interest in the joint venture. In April 2017, the Company acquired the remaining joint venture interests and increased its ownership interest to 100 percent. See Note 3: Recent Transactions – Consolidation.  (f) On February 15, 2017, the Company sold its 7.5 percent interest in Elmajo Urban Renewal Associates, LLC and Estuary Urban Renewal Unit B, LLC joint ventures that own operating multi-family properties, located in Weehawken, New Jersey for a combined sales price of $5.1 million.  (g) The Company also owns a 50 percent interest in a vacant land to accommodate the development of approximately 295 additional units of which 252 are currently approved.  (h) On December 7, 2017, simultaneous with the financing of the construction loan, the Company converted its 20 percent subordinate interest to 40 percent pari-passu interest.  (i) The construction loan had a maximum borrowing amount of $77.4 million and provided, subject to certain conditions, two one -year extension options with a fee of 25 basis points for each year. On March 31, 2017, the Company exercised its first one -year extension option and concurrently the maximum borrowing amount was reduced to $75 million.  (j) The construction/permanent loan has a maximum borrowing amount of $192 million. The Company owns an 85 percent interest with shared control over major decisions such as, approval of budgets, property financings and leasing guidelines. The development project was placed in service in second quarter 2017.  (k) The Company also owns a 20 percent residual interest in undeveloped land parcels: parcels 6, I, and J that can accommodate the development of 836 apartment units.  (l) On September 21, 2017, the joint venture agreement was terminated. Accordingly, the Company wrote off the carrying value of its investment in the joint venture and recorded a loss of $1.4 million on the disposition of its joint venture interest.  (m) On February 3, 2017, the Company acquired the equity interest of its partner. See Note 3: Recent Transactions - Consolidation.  (n) On January 31, 2017, the Company sold its equity interest in the joint venture. See Note 3: Recent Transactions - Unconsolidated Joint Venture Activity.  (o) Includes undivided interests in the same manner as investments in noncontrolling partnership, pursuant to ASC 970-323-25-12. On September 29, 2017, the Company sold its equity interest to its joint venture partner, which included the retirement of the Company's share in the debt of $75 million. See Note 3: Recent Transactions - Unconsolidated Joint Venture Activity.  (p) The Company owns other interests in various unconsolidated joint ventures, including interests in assets previously owned and interest in ventures whose businesses are related to its core operations. These ventures are not expected to significantly impact the Company's operations in the near term. The following is a summary of the Compan y’s equity in earnings (loss) of unconsolidated joint ventures for the years ended December 31, 2017 , 2016 and 2015: (dollars in thousands)     Year Ended December 31,  Entity / Property Name 2017 2016 2015  Multi-family  Marbella RoseGarden, L.L.C./ Marbella $ 334 $ 231 $ 231  RoseGarden Monaco Holdings, L.L.C./ Monaco (265) (937) (1,224)  Rosewood Morristown, L.L.C. / Metropolitan at 40 Park (311) (317) (364)  Riverwalk G Urban Renewal, L.L.C./ RiverTrace at Port Imperial 196 (1,146) (955)  Crystal House Apartments Investors LLC / Crystal House (923) (870) (123)  Riverwalk C Urban Renewal, L.L.C. (653) (58) (306)  RoseGarden Marbella South, L.L.C./ Marbella II 93 (202) -  Estuary Urban Renewal Unit B, LLC / Lincoln Harbor (Bldg B) - - 1  Riverpark at Harrison I, L.L.C./ Riverpark at Harrison (252) (190) (363)  Capitol Place Mezz LLC / Station Townhouses (1,793) (2,440) (3,687)  Harborside Unit A Urban Renewal, L.L.C. / URL Harborside (6,356) (219) -  Roseland/Port Imperial Partners, L.P. (219) (62) (168)  Grand Jersey Waterfront URA, L.L.C./ Liberty Landing (15) (80) (32)  Hillsborough 206 Holdings, L.L.C./ Hillsborough 206 (25) (53) (5)  Plaza VIII & IX Associates, L.L.C./ Vacant land (parking operations) 386 393 344  Office  Red Bank Corporate Plaza, L.L.C./ Red Bank 238 448 392  12 Vreeland Associates, L.L.C./ 12 Vreeland Road 496 347 270  BNES Associates III / Offices at Crystal Lake 89 (15) 115  KPG-P 100 IMW JV, LLC / 100 Independence Mall West - - (800)  Keystone-Penn - 600 3,812  Keystone-TriState - (1,672) (2,182)  KPG-MCG Curtis JV, L.L.C./ Curtis Center (436) (92) 475  Other  Roseland/North Retail, L.L.C./ Riverwalk at Port Imperial (81) (52) (70)  South Pier at Harborside / Hyatt Regency Jersey City on the Hudson (a) 3,277 24,180 3,036  Other 139 994 (1,569)  Company's equity in earnings (loss) of unconsolidated joint ventures (b) $ (6,081) $ 18,788 $ (3,172) (a) Equity in earnings in 2016 includes the effect of distributions received from the joint venture’s refinancing. See Recent Joint Venture Transactions following in this footnote. (b) Amounts are net of amortization of basis differences of $792 , $436 and $336 for the years ended December 31, 2017, 2016 and 2015, respectively.  The following is a summary of the combined financial position of the unconsolidated joint ventures in which the Company had investment interests as of December 31, 2017 and 2016 : (dollars in thousands)     December 31, December 31,  2017 2016  Assets:  Rental property, net $ 931,419 $ 1,746,233  Other assets 207,903 278,289  Total assets $ 1,139,322 $ 2,024,522  Liabilities and partners'/  members' capital:  Mortgages and loans payable $ 689,412 $ 1,350,973  Other liabilities 80,746 247,212  Partners'/members' capital 369,164 426,337  Total liabilities and  partners'/members' capital $ 1,139,322 $ 2,024,522   The following is a summary of the combined results from operations of the unconsolidated joint ventures for the period in which the Company had investment interests during the year s ended December 31, 2017 , 2016 and 2015 : (dollars in thousands)     Year Ended December 31,  2017 2016 2015  Total revenues $ 358,751 $ 377,711 $ 318,980  Operating and other expenses (297,492) (262,703) (220,982)  Depreciation and amortization (31,020) (75,512) (71,711)  Interest expense (25,822) (58,390) (52,972)  Net income (loss) $ 4,417 $ (18,894) $ (26,685) 

Deferred Charges, Goodwill And

Deferred Charges, Goodwill And Other Assets, Net	12 Months Ended
	Dec. 31, 2017
Deferred Charges, Goodwill And Other Assets [Line Items]
Deferred Charges, Goodwill And Other Assets, Net	5. DEFERRED CHARGES , GOODWILL AND OTHER ASSETS , NET    December 31,  (dollars in thousands) 2017 2016  Deferred leasing costs $ 199,515 $ 220,947  Deferred financing costs - unsecured revolving credit facility (a) 4,945 5,400  204,460 226,347  Accumulated amortization (98,956) (107,359)  Deferred charges, net 105,504 118,988  Notes receivable (b) 50,167 13,251  In-place lease values, related intangibles and other assets, net (c) (d) 102,757 72,046  Goodwill (e) 2,945 2,945  Prepaid expenses and other assets, net (f) 80,947 60,720   Total deferred charges, goodwill and other assets, net $ 342,320 $ 267,950  (a) Deferred financing costs related to all other debt liabilities (other than for the unsecured revolving credit facility) are netted against those debt liabilities for all periods presented. See Note 2: Significant Accounting Policies – Deferred Financing Costs. (b) Includes as of December 31, 2017 : a mortgage receivable with a balance of $ 45.7 million (acquired in August 2017) which bears interest at 5.85 percent and matures in July 2019 , with a three -month extension option and an interest-free note receivable with a net present value of $2.5 million which matures in April 2023 . The Company believes these balances are fully collectible. (c) In accordance with ASC 805, Business Combinations, the Company recognizes rental revenue of acquired above and below market lease intangibles over the terms of the respective leases. The impact of amortizing the acquired above and below-market lease intangibles increased revenue by approximately $ 7.9 million, $1.9 million and $0.2 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. The following table summarizes, as of December 31, 2017 , the scheduled amortization of the Company’s acquired above and below-market lease intangibles for each of the five succeeding years (dollars in thousands) .     Acquired Above- Acquired Below-  Market Lease Market Lease Total  Year Intangibles Intangibles Amortization  2018 $ (5,084) $ 6,888 $ 1,804  2019 (4,716) 5,183 467  2020 (3,398) 4,304 906  2021 (2,779) 4,186 1,407  2022 (2,665) 4,063 1,398  (d) The value of acquired in-place lease intangibles are amortized to expense over the remaining initial terms of the respective leases. The impact of the amortization of acquired in-place lease values is included in depreciation and amortization expense and amounted to approximately $32.2 million, $14.3 million and $1.4 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. The following table summarizes, as of December 31, 2017 , the scheduled amortization of the Company’s acquired in-place lease values for each of the five succeeding years (dollars in thousands) .    Year  2018 $ 10,657  2019 8,406  2020 7,078  2021 6,347  2022 5,526   (e) All goodwill is attributable to the Company’s Multi-family Services segment. (f) Includes as of December 31, 2017 , $26.9 million of proceeds from property sales held by a qualified intermediary.  DERIVATIVE FINANCIAL INSTRUMENTS  Cash Flow Hedges of Interest Rate Risk The Company’s objectives in using interest rate derivatives are to add stability to interest expense and to manage its exposure to interest rate movements. To accomplish this objective, the Company primarily uses interest rate swaps as part of its interest rate risk management strategy. As of December 31, 2017 , the Company had outstanding interest rate swaps with a combined notional value of $675 million that were designated as cash flow hedges of interest rate risk. During the year ending December 31, 2017 , such derivatives were used to hedge the variable cash flows associated with existing variable-rate debt.  The effective portion of changes in the fair value of derivatives designated and that qualify as cash flow hedges is recorded in accumulated other comprehensive income and is subsequently reclassified into earnings in the period that the hedged forecasted transaction affects earnings. The ineffective portion of the change in fair value of the derivatives is recognized directly in earnings. During the years ended December 31, 2017 , 2016 and 2015 the Company recorded ineffectiveness gain (loss) of $(37,000) , $0.6 million and zero , respectively, which is included in interest and other investment income (loss) in the consolidated statements of operations, attributable to a floor mismatch in the underlying indices of the derivatives and the hedged interest payments made on its variable-rate debt. Amounts reported in accumulated other comprehensive income related to derivatives will be reclassified to interest expense as interest payments are made on the Company’s variable-rate debt. During the next 12 months, the Company estimates that an additional $1.5 million will be reclassified as a decrease to interest expense.  Undesignated Cash Flow Hedges of Interest Rate Risk Interest rate caps not designated as hedges are not speculative and are used to manage the Company’s exposure to interest rate movements but do not meet the strict hedge accounting requirements. Changes in the fair value of derivatives not designated in hedging relationships are recorded directly in earnings. The Company recognized expenses of zero , $ 2,000 and $93,000 for the year s ended December 31, 2017 , 2016 and 2015 , respectively, which is included in interest and other investment income (loss) in the consolidated statements of operations.  The table below presents the fair value of the Company’s derivative financial instruments as well as their classification on the Balance Sheet as of December 31, 2017 and 2016 . (dollars in thousands)     Fair Value  Asset Derivatives designated December 31,  as hedging instruments 2017 2016 Balance sheet location  Interest rate swaps $ 8,060 $ 2,847 Deferred charges, goodwill and other assets  The table below presents the effect of the Company’s derivative financial instruments on the Income Statement for the year s ending December 31, 2017 , 2016 and 2015 . (dollars in thousands)     Derivatives in Cash Flow Hedging Relationships Amount of Gain or (Loss) Recognized in OCI on Derivative (Effective Portion) Location of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion) Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion) Location of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing) Amount of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion, Reclassification for Forecasted Transactions No Longer Probable of Occurring and Amount Excluded from Effectiveness Testing)  2017 2016 2015 2017 2016 2015 2017 2016 2015  Year ended December 31,   Interest rate swaps $ 2,869 $ (1,183) $ - Interest expense $ (2,381) $ (3,398) $ - Interest and other investment income (loss) $ (37) $ 631 $ -   Credit-risk-related Contingent Features The Company has agreements with each of its derivative counterparties that contain a provision where the Company could be declared in default on its derivative obligations if repayment of the underlying indebtedness is accelerated by the lender due to the Company's default on the indebtedness. As of December 31, 2017 , the Company did not have derivatives in a net liability position including accrued interest but excluding any adjustment for nonperformance risk related to these agreements. As of December 31, 2017 , the Company has not posted any collateral related to these agreements.
Mack-Cali Realty LP [Member]
Deferred Charges, Goodwill And Other Assets [Line Items]
Deferred Charges, Goodwill And Other Assets, Net	5. DEFERRED CHARGES , GOODWILL AND OTHER ASSETS , NET    December 31,  (dollars in thousands) 2017 2016  Deferred leasing costs $ 199,515 $ 220,947  Deferred financing costs - unsecured revolving credit facility (a) 4,945 5,400  204,460 226,347  Accumulated amortization (98,956) (107,359)  Deferred charges, net 105,504 118,988  Notes receivable (b) 50,167 13,251  In-place lease values, related intangibles and other assets, net (c) (d) 102,757 72,046  Goodwill (e) 2,945 2,945  Prepaid expenses and other assets, net (f) 80,947 60,720   Total deferred charges, goodwill and other assets, net $ 342,320 $ 267,950  (a) Deferred financing costs related to all other debt liabilities (other than for the unsecured revolving credit facility) are netted against those debt liabilities for all periods presented. See Note 2: Significant Accounting Policies – Deferred Financing Costs. (b) Includes as of December 31, 2017 : a mortgage receivable with a balance of $ 45.7 million (acquired in August 2017) which bears interest at 5.85 percent and matures in July 2019 , with a three -month extension option and an interest-free note receivable with a net present value of $2.5 million which matures in April 2023 . The Company believes these balances are fully collectible. (c) In accordance with ASC 805, Business Combinations, the Company recognizes rental revenue of acquired above and below market lease intangibles over the terms of the respective leases. The impact of amortizing the acquired above and below-market lease intangibles increased revenue by approximately $ 7.9 million, $1.9 million and $0.2 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. The following table summarizes, as of December 31, 2017 , the scheduled amortization of the Company’s acquired above and below-market lease intangibles for each of the five succeeding years (dollars in thousands) .     Acquired Above- Acquired Below-  Market Lease Market Lease Total  Year Intangibles Intangibles Amortization  2018 $ (5,084) $ 6,888 $ 1,804  2019 (4,716) 5,183 467  2020 (3,398) 4,304 906  2021 (2,779) 4,186 1,407  2022 (2,665) 4,063 1,398  (d) The value of acquired in-place lease intangibles are amortized to expense over the remaining initial terms of the respective leases. The impact of the amortization of acquired in-place lease values is included in depreciation and amortization expense and amounted to approximately $32.2 million, $14.3 million and $1.4 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. The following table summarizes, as of December 31, 2017 , the scheduled amortization of the Company’s acquired in-place lease values for each of the five succeeding years (dollars in thousands) .    Year  2018 $ 10,657  2019 8,406  2020 7,078  2021 6,347  2022 5,526   (e) All goodwill is attributable to the Company’s Multi-family Services segment. (f) Includes as of December 31, 2017 , $26.9 million of proceeds from property sales held by a qualified intermediary.  DERIVATIVE FINANCIAL INSTRUMENTS  Cash Flow Hedges of Interest Rate Risk The Company’s objectives in using interest rate derivatives are to add stability to interest expense and to manage its exposure to interest rate movements. To accomplish this objective, the Company primarily uses interest rate swaps as part of its interest rate risk management strategy. As of December 31, 2017 , the Company had outstanding interest rate swaps with a combined notional value of $675 million that were designated as cash flow hedges of interest rate risk. During the year ending December 31, 2017 , such derivatives were used to hedge the variable cash flows associated with existing variable-rate debt.  The effective portion of changes in the fair value of derivatives designated and that qualify as cash flow hedges is recorded in accumulated other comprehensive income and is subsequently reclassified into earnings in the period that the hedged forecasted transaction affects earnings. The ineffective portion of the change in fair value of the derivatives is recognized directly in earnings. During the years ended December 31, 2017 , 2016 and 2015 the Company recorded ineffectiveness gain (loss) of $(37,000) , $0.6 million and zero , respectively, which is included in interest and other investment income (loss) in the consolidated statements of operations, attributable to a floor mismatch in the underlying indices of the derivatives and the hedged interest payments made on its variable-rate debt. Amounts reported in accumulated other comprehensive income related to derivatives will be reclassified to interest expense as interest payments are made on the Company’s variable-rate debt. During the next 12 months, the Company estimates that an additional $1.5 million will be reclassified as a decrease to interest expense.  Undesignated Cash Flow Hedges of Interest Rate Risk Interest rate caps not designated as hedges are not speculative and are used to manage the Company’s exposure to interest rate movements but do not meet the strict hedge accounting requirements. Changes in the fair value of derivatives not designated in hedging relationships are recorded directly in earnings. The Company recognized expenses of zero , $ 2,000 and $93,000 for the year s ended December 31, 2017 , 2016 and 2015 , respectively, which is included in interest and other investment income (loss) in the consolidated statements of operations.  The table below presents the fair value of the Company’s derivative financial instruments as well as their classification on the Balance Sheet as of December 31, 2017 and 2016 . (dollars in thousands)     Fair Value  Asset Derivatives designated December 31,  as hedging instruments 2017 2016 Balance sheet location  Interest rate swaps $ 8,060 $ 2,847 Deferred charges, goodwill and other assets  The table below presents the effect of the Company’s derivative financial instruments on the Income Statement for the year s ending December 31, 2017 , 2016 and 2015 . (dollars in thousands)     Derivatives in Cash Flow Hedging Relationships Amount of Gain or (Loss) Recognized in OCI on Derivative (Effective Portion) Location of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion) Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion) Location of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing) Amount of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion, Reclassification for Forecasted Transactions No Longer Probable of Occurring and Amount Excluded from Effectiveness Testing)  2017 2016 2015 2017 2016 2015 2017 2016 2015  Year ended December 31,   Interest rate swaps $ 2,869 $ (1,183) $ - Interest expense $ (2,381) $ (3,398) $ - Interest and other investment income (loss) $ (37) $ 631 $ -   Credit-risk-related Contingent Features The Company has agreements with each of its derivative counterparties that contain a provision where the Company could be declared in default on its derivative obligations if repayment of the underlying indebtedness is accelerated by the lender due to the Company's default on the indebtedness. As of December 31, 2017 , the Company did not have derivatives in a net liability position including accrued interest but excluding any adjustment for nonperformance risk related to these agreements. As of December 31, 2017 , the Company has not posted any collateral related to these agreements.

Restricted Cash

Restricted Cash	12 Months Ended
	Dec. 31, 2017
Restricted Cash [Line Items]
Restricted Cash	6. RESTRICTED CASH  Restricted cash generally includes tenant and resident security deposits for certain of the Company’s properties, and escrow and reserve funds for debt service, real estate taxes, property insurance, capital improvements, tenant improvements, and leasing costs established pursuant to certain mortgage financing arrangements, and is comprised of the following: (dollars in thousands)    December 31,  2017 2016  Security deposits $ 9,446 $ 8,778  Escrow and other reserve funds 30,346 45,174   Total restricted cash $ 39,792 $ 53,952 
Mack-Cali Realty LP [Member]
Restricted Cash [Line Items]
Restricted Cash	6. RESTRICTED CASH  Restricted cash generally includes tenant and resident security deposits for certain of the Company’s properties, and escrow and reserve funds for debt service, real estate taxes, property insurance, capital improvements, tenant improvements, and leasing costs established pursuant to certain mortgage financing arrangements, and is comprised of the following: (dollars in thousands)    December 31,  2017 2016  Security deposits $ 9,446 $ 8,778  Escrow and other reserve funds 30,346 45,174   Total restricted cash $ 39,792 $ 53,952 

Senior Unsecured Notes

Senior Unsecured Notes	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Line Items]
Senior Unsecured Notes	7. SENIOR UNSECURED NOTES  A summary of the Company’s senior unsecured notes as of December 31, 2017 and 2016 is as follows : (dollars in thousands)     December 31, December 31, Effective  2017 2016 Rate (1)  2.500% Senior Unsecured Notes, due December 15, 2017 (2) - $ 250,000 2.803 %  4.500% Senior Unsecured Notes, due April 18, 2022 $ 300,000 300,000 4.612 %  3.150% Senior Unsecured Notes, due May 15, 2023 275,000 275,000 3.517 %  Principal balance outstanding 575,000 825,000  Adjustment for unamortized debt discount (3,505) (4,430)  Unamortized deferred financing costs (2,350) (3,215)   Total senior unsecured notes, net $ 569,145 $ 817,355  (1) Includes the cost of terminated treasury lock agreements (if any), offering and other transaction costs and the discount/premium on the notes, as applicable. (2) T he Company repaid these notes at maturity using available cash and borrowings under the Company’s unsecured revolving credit facility. The terms of the Company’s senior unsecured notes include certain restrictions and covenants which require compliance with financial ratios relating to the maximum amount of debt leverage, the maximum amount of secured indebtedness, the minimum amount of debt service coverage and the maximum amount of unsecured debt as a percent of unsecured assets. The Company was in compliance with its debt covenants under the indenture relating to its senior unsecured notes as of December 31, 2017 .
Mack-Cali Realty LP [Member]
Debt Disclosure [Line Items]
Senior Unsecured Notes	7. SENIOR UNSECURED NOTES  A summary of the Company’s senior unsecured notes as of December 31, 2017 and 2016 is as follows : (dollars in thousands)     December 31, December 31, Effective  2017 2016 Rate (1)  2.500% Senior Unsecured Notes, due December 15, 2017 (2) - $ 250,000 2.803 %  4.500% Senior Unsecured Notes, due April 18, 2022 $ 300,000 300,000 4.612 %  3.150% Senior Unsecured Notes, due May 15, 2023 275,000 275,000 3.517 %  Principal balance outstanding 575,000 825,000  Adjustment for unamortized debt discount (3,505) (4,430)  Unamortized deferred financing costs (2,350) (3,215)   Total senior unsecured notes, net $ 569,145 $ 817,355  (1) Includes the cost of terminated treasury lock agreements (if any), offering and other transaction costs and the discount/premium on the notes, as applicable. (2) T he Company repaid these notes at maturity using available cash and borrowings under the Company’s unsecured revolving credit facility. The terms of the Company’s senior unsecured notes include certain restrictions and covenants which require compliance with financial ratios relating to the maximum amount of debt leverage, the maximum amount of secured indebtedness, the minimum amount of debt service coverage and the maximum amount of unsecured debt as a percent of unsecured assets. The Company was in compliance with its debt covenants under the indenture relating to its senior unsecured notes as of December 31, 2017 .

Unsecured Revolving Credit Faci

Unsecured Revolving Credit Facility And Term Loans	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Line Items]
Unsecured Revolving Credit Facility And Term Loans	8. UNSECURED REVOLVING CREDIT FACILITY AND TERM LOANS  On January 25, 2017, the Company entered into an amended revolving credit facility and new term loan agreement (“2017 Credit Agreement”) with a group of 13 lenders. Pursuant to the 2017 Credit Agreement, the Company refinanced its existing $600 million unsecured revolving credit facility (“2017 Credit Facility”) and entered into a new $325 million unsecured term loan facility (“2017 Term Loan”). The terms of the 2017 Credit Facility include: (1) a four -year term ending in January 2021 , with two six -month extension options; (2) revolving credit loans may be made to the Company in an aggregate principal amount of up to $600 million (subject to increase as discussed below), with a sublimit under the 2017 Credit Facility for the issuance of letters of credit in an amount not to exceed $60 million (subject to increase as discussed below); (3) an interest rate based on the Operating Partnership’s unsecured debt ratings from Moody’s or S&P, currently the London Inter-Bank Offered Rate (“LIBOR”) plus 120 basis points, or, at the Operating Partnership’s option, if it no longer maintains a debt rating from Moody’s or S&P or such debt ratings fall below Baa3 and BBB-, based on a defined leverage ratio; and (4) a facility fee payable quarterly based on the Operating Partnership’s unsecured debt ratings from Moody’s or S&P, currently 25 basis points, or, at the Operating Partnership’s option, if it no longer maintains a debt rating from Moody’s or S&P or such debt ratings fall below Baa3 and BBB-, based on a defined leverage ratio.  The interest rates on outstanding borrowings, alternate base rate loans and the facility fee on the current borrowing capacity payable quarterly in arrears on the 2017 Credit Facility are based upon the Operating Partnership’s unsecured debt ratings, as follows:     Interest Rate -  Applicable Basis Points  Operating Partnership's Interest Rate - Above LIBOR for  Unsecured Debt Ratings: Applicable Basis Points Alternate Base Rate Facility Fee  Higher of S&P or Moody's Above LIBOR Loans Basis Points  No ratings or less than BBB-/Baa3 155.0 55.0 30.0  BBB- or Baa3 (current interest rate based on Company's election) 120.0 20.0 25.0  BBB or Baa2 100.0 0.0 20.0  BBB+ or Baa1 90.0 0.0 15.0  A- or A3 or higher 87.5 0.0 12.5  If the Company elected to use the defined leverage ratio, the interest rate under the 2017 Credit Facility would be based on the following total leverage ratio grid:     Interest Rate -  Applicable Basis Points  Interest Rate - Above LIBOR for  Applicable Basis Alternate Base Rate Facility Fee  Total Leverage Ratio Points above LIBOR Loans Basis Points  <45% 125.0 25.0 20.0  ≥45% and <50% (current ratio) 130.0 30.0 25.0  ≥50% and <55% 135.0 35.0 30.0  ≥55% 160.0 60.0 35.0  The terms of the 2017 Term Loan include: (1) a three -year term ending in January 2020 , with two one -year extension options; (2) multiple draws of the term loan commitments may be made within 12 months of the effective date of the 2017 Credit Agreement up to an aggregate principal amount of $325 million (subject to increase as discussed below), with no requirement to be drawn in full; provided, that, if the Company does not borrow at least 50 percent of the initial term commitment from the term lenders (i.e. 50 percent of $325 million) on or before July 25, 2017, the amount of unused term loan commitments shall be reduced on such date so that, after giving effect to such reduction, the amount of unused term loan commitments is not greater than the outstanding term loans on such date; (3) a n interest rate based on the Operating Partnership’s unsecured debt ratings from Moody’s or S&P, currently the LIBOR plus 140 basis points, or, at the Operating Partnership’s option if it no longer maintains a debt rating from Moody’s or S&P or such debt ratings fall below Baa3 and BBB-, based on a defined leverage ratio; and (4) a term commitment fee on any unused term loan commitment during the first 12 months after the effective date of the 2017 Credit Agreement at a rate of 0.25 percent per annum on the sum of the average daily unused portion of the aggregate term loan commitments.  On March 22, 2017, the Company drew the full $325 million available under the 2017 Term Loan. On March 29, 2017, the Company executed interest rate swap arrangements to fix LIBOR with an aggregate average rate of 1.6473% for the swaps and a current aggregate fixed rate of 3.0473% on borrowings under the 2017 Term Loan.  On up to four occasions at any time after the effective date of the 2017 Credit Agreement , the Company may elect to request (1) an increase to the existing revolving credit commitments (any such increase, the “New Revolving Credit Commitments”) and/or (2) the establishment of one or more new term loan commitments (the “New Term Commitments”, together with the 2017 Credit Commitments, the “Incremental Commitments”), by up to an aggregate amount not to exceed $350 million for all Incremental Commitments. The Company may also request that the sublimit for letters of credit available under the 2017 Credit Facility be increased to $100 million (without arranging any New Revolving Credit Commitments). No lender or letter of credit issued has any obligation to accept any Incremental Commitment or any increase to the letter of credit subfacility. There is no premium or penalty associated with full or partial prepayment of borrowings under the 2017 Credit Agreement. The 2017 Credit Agreement, which applies to both the 2017 Credit Facility and 2017 Term Loan, includes certain restrictions and covenants which limit, among other things the incurrence of additional indebtedness, the incurrence of liens and the disposition of real estate properties (to the extent that: (i) such property dispositions cause the Company to default on any of the financial ratios of the 2017 Credit Agreement (described below), or (ii) the property dispositions are completed while the Company is under an event of default under the 2017 Credit Agreement, unless, under certain circumstances, such disposition is being carried out to cure such default), and which require compliance with financial ratios relating to the maximum leverage ratio (60 percent), the maximum amount of secured indebtedness (40 percent), the minimum amount of fixed charge coverage (1.5 times), the maximum amount of unsecured indebtedness (60 percent), the minimum amount of unencumbered property interest coverage (2.0 times) and certain investment limitations (generally 15 percent of total capitalization). If an event of default has occurred and is continuing, the entire outstanding balance under the 2017 Credit Agreement may (or, in the case of any bankruptcy event of default, shall) become immediately due and payable, and the Company will not make any excess distributions except to enable the General Partner to continue to qualify as a REIT under the IRS Code.  Before it amended and restated its unsecured revolving credit facility in January 2017, the Company had a $600 million unsecured revolving credit facility with a group of 17 lenders that was scheduled to mature in July 2017. The interest rate on outstanding borrowings (not electing the Company’s competitive bid feature) and the facility fee on the current borrowing capacity payable quarterly in arrears was based upon the Operating Partnership’s unsecured debt ratings at the time, as follows:     Operating Partnership's Interest Rate -  Unsecured Debt Ratings: Applicable Basis Points Facility Fee  Higher of S&P or Moody's Above LIBOR Basis Points  No ratings or less than BBB-/Baa3 170.0 35.0  BBB- or Baa3 (current since January 2017 amendment) 130.0 30.0  BBB or Baa2 110.0 20.0  BBB+ or Baa1 100.0 15.0  A- or A3 or higher 92.5 12.5  In January 2016, the Company obtained a $350 million unsecured term loan (“2016 Term Loan”), which matures in January 2019 with two one ‑year extension options. The interest rate for the term loan is currently 140 basis points over LIBOR, subject to adjustment on a sliding scale based on the Operating Partnership’s unsecured debt ratings, or, at the Company's option, a defined leverage ratio. The Company entered into interest rate swap arrangements to fix LIBOR for the duration of the term loan. Including costs, the current all-in fixed rate is 3.13 percent. The proceeds from the loan were used primarily to repay outstanding borrowings on the Company’s then existing unsecured revolving credit facility and to repay $200 million senior unsecured notes that matured on January 15, 2016 .  The interest rate on the 2016 Term Loan is based upon the Operating Partnership’s unsecured debt ratings, as follows:    Operating Partnership's Interest Rate -  Unsecured Debt Ratings: Applicable Basis Points  Higher of S&P or Moody's Above LIBOR  No ratings or less than BBB-/Baa3 185.0  BBB- or Baa3 (current interest rate based on Company's election) 140.0  BBB or Baa2 115.0  BBB+ or Baa1 100.0  A- or A3 or higher 90.0  If the Company elected to use the defined leverage ratio, the interest rate under the 2016 Term Loan would be based on the following total leverage ratio grid:     Interest Rate -  Applicable Basis  Total Leverage Ratio Points above LIBOR  < 45% 145.0  ≥ 45% and < 50% (current ratio) 155.0  ≥ 50% and < 55% 165.0  ≥ 55% 195.0  The terms of the 2016 Term Loan include certain restrictions and covenants which limit, among other things the incurrence of additional indebtedness, the incurrence of liens and the disposition of real estate properties (to the extent that: (i) such property dispositions cause the Company to default on any of the financial ratios of the term loan described below, or (ii) the property dispositions are completed while the Company is under an event of default under the term loan, unless, under certain circumstances, such disposition is being carried out to cure such default), and which require compliance with financial ratios relating to the maximum leverage ratio (60 percent), the maximum amount of secured indebtedness (40 percent), the minimum amount of fixed charge coverage (1.5 times), the maximum amount of unsecured indebtedness (60 percent), the minimum amount of unencumbered property interest coverage (2.0 times) and certain investment limitations (generally 15 percent of total capitalization). If an event of default has occurred and is continuing, the Company will not make any excess distributions except to enable the General Partner to continue to qualify as a REIT under the IRS Code.  The Company was in compliance with its debt covenants under its unsecured revolving credit facility and term loans as of December 31, 2017 .  As of December 31, 2017 and 2016 , the Company’s unsecured credit facility and term loans totaled $822.3 million and $634.1 million, respectively, comprised of: $150.0 million of outstanding borrowings under its unsecured revolving credit facility, $349.0 million from the 2016 Term Loan (net of unamortized deferred financing costs of $1.0 million) and $323.3 million from the 2017 Term Loan (net of unamortized deferred financing costs of $1.7 million) as of December 31, 2017, and $286 million of outstanding borrowings under its unsecured revolving credit facility and $348.1 from the 2016 Term Loan (net of unamortized deferred financing costs of $1.9 million) as of December 31, 2016.
Mack-Cali Realty LP [Member]
Debt Disclosure [Line Items]
Unsecured Revolving Credit Facility And Term Loans	8. UNSECURED REVOLVING CREDIT FACILITY AND TERM LOANS  On January 25, 2017, the Company entered into an amended revolving credit facility and new term loan agreement (“2017 Credit Agreement”) with a group of 13 lenders. Pursuant to the 2017 Credit Agreement, the Company refinanced its existing $600 million unsecured revolving credit facility (“2017 Credit Facility”) and entered into a new $325 million unsecured term loan facility (“2017 Term Loan”). The terms of the 2017 Credit Facility include: (1) a four -year term ending in January 2021 , with two six -month extension options; (2) revolving credit loans may be made to the Company in an aggregate principal amount of up to $600 million (subject to increase as discussed below), with a sublimit under the 2017 Credit Facility for the issuance of letters of credit in an amount not to exceed $60 million (subject to increase as discussed below); (3) an interest rate based on the Operating Partnership’s unsecured debt ratings from Moody’s or S&P, currently the London Inter-Bank Offered Rate (“LIBOR”) plus 120 basis points, or, at the Operating Partnership’s option, if it no longer maintains a debt rating from Moody’s or S&P or such debt ratings fall below Baa3 and BBB-, based on a defined leverage ratio; and (4) a facility fee payable quarterly based on the Operating Partnership’s unsecured debt ratings from Moody’s or S&P, currently 25 basis points, or, at the Operating Partnership’s option, if it no longer maintains a debt rating from Moody’s or S&P or such debt ratings fall below Baa3 and BBB-, based on a defined leverage ratio.  The interest rates on outstanding borrowings, alternate base rate loans and the facility fee on the current borrowing capacity payable quarterly in arrears on the 2017 Credit Facility are based upon the Operating Partnership’s unsecured debt ratings, as follows:     Interest Rate -  Applicable Basis Points  Operating Partnership's Interest Rate - Above LIBOR for  Unsecured Debt Ratings: Applicable Basis Points Alternate Base Rate Facility Fee  Higher of S&P or Moody's Above LIBOR Loans Basis Points  No ratings or less than BBB-/Baa3 155.0 55.0 30.0  BBB- or Baa3 (current interest rate based on Company's election) 120.0 20.0 25.0  BBB or Baa2 100.0 0.0 20.0  BBB+ or Baa1 90.0 0.0 15.0  A- or A3 or higher 87.5 0.0 12.5  If the Company elected to use the defined leverage ratio, the interest rate under the 2017 Credit Facility would be based on the following total leverage ratio grid:     Interest Rate -  Applicable Basis Points  Interest Rate - Above LIBOR for  Applicable Basis Alternate Base Rate Facility Fee  Total Leverage Ratio Points above LIBOR Loans Basis Points  <45% 125.0 25.0 20.0  ≥45% and <50% (current ratio) 130.0 30.0 25.0  ≥50% and <55% 135.0 35.0 30.0  ≥55% 160.0 60.0 35.0  The terms of the 2017 Term Loan include: (1) a three -year term ending in January 2020 , with two one -year extension options; (2) multiple draws of the term loan commitments may be made within 12 months of the effective date of the 2017 Credit Agreement up to an aggregate principal amount of $325 million (subject to increase as discussed below), with no requirement to be drawn in full; provided, that, if the Company does not borrow at least 50 percent of the initial term commitment from the term lenders (i.e. 50 percent of $325 million) on or before July 25, 2017, the amount of unused term loan commitments shall be reduced on such date so that, after giving effect to such reduction, the amount of unused term loan commitments is not greater than the outstanding term loans on such date; (3) a n interest rate based on the Operating Partnership’s unsecured debt ratings from Moody’s or S&P, currently the LIBOR plus 140 basis points, or, at the Operating Partnership’s option if it no longer maintains a debt rating from Moody’s or S&P or such debt ratings fall below Baa3 and BBB-, based on a defined leverage ratio; and (4) a term commitment fee on any unused term loan commitment during the first 12 months after the effective date of the 2017 Credit Agreement at a rate of 0.25 percent per annum on the sum of the average daily unused portion of the aggregate term loan commitments.  On March 22, 2017, the Company drew the full $325 million available under the 2017 Term Loan. On March 29, 2017, the Company executed interest rate swap arrangements to fix LIBOR with an aggregate average rate of 1.6473% for the swaps and a current aggregate fixed rate of 3.0473% on borrowings under the 2017 Term Loan.  On up to four occasions at any time after the effective date of the 2017 Credit Agreement , the Company may elect to request (1) an increase to the existing revolving credit commitments (any such increase, the “New Revolving Credit Commitments”) and/or (2) the establishment of one or more new term loan commitments (the “New Term Commitments”, together with the 2017 Credit Commitments, the “Incremental Commitments”), by up to an aggregate amount not to exceed $350 million for all Incremental Commitments. The Company may also request that the sublimit for letters of credit available under the 2017 Credit Facility be increased to $100 million (without arranging any New Revolving Credit Commitments). No lender or letter of credit issued has any obligation to accept any Incremental Commitment or any increase to the letter of credit subfacility. There is no premium or penalty associated with full or partial prepayment of borrowings under the 2017 Credit Agreement. The 2017 Credit Agreement, which applies to both the 2017 Credit Facility and 2017 Term Loan, includes certain restrictions and covenants which limit, among other things the incurrence of additional indebtedness, the incurrence of liens and the disposition of real estate properties (to the extent that: (i) such property dispositions cause the Company to default on any of the financial ratios of the 2017 Credit Agreement (described below), or (ii) the property dispositions are completed while the Company is under an event of default under the 2017 Credit Agreement, unless, under certain circumstances, such disposition is being carried out to cure such default), and which require compliance with financial ratios relating to the maximum leverage ratio (60 percent), the maximum amount of secured indebtedness (40 percent), the minimum amount of fixed charge coverage (1.5 times), the maximum amount of unsecured indebtedness (60 percent), the minimum amount of unencumbered property interest coverage (2.0 times) and certain investment limitations (generally 15 percent of total capitalization). If an event of default has occurred and is continuing, the entire outstanding balance under the 2017 Credit Agreement may (or, in the case of any bankruptcy event of default, shall) become immediately due and payable, and the Company will not make any excess distributions except to enable the General Partner to continue to qualify as a REIT under the IRS Code.  Before it amended and restated its unsecured revolving credit facility in January 2017, the Company had a $600 million unsecured revolving credit facility with a group of 17 lenders that was scheduled to mature in July 2017. The interest rate on outstanding borrowings (not electing the Company’s competitive bid feature) and the facility fee on the current borrowing capacity payable quarterly in arrears was based upon the Operating Partnership’s unsecured debt ratings at the time, as follows:     Operating Partnership's Interest Rate -  Unsecured Debt Ratings: Applicable Basis Points Facility Fee  Higher of S&P or Moody's Above LIBOR Basis Points  No ratings or less than BBB-/Baa3 170.0 35.0  BBB- or Baa3 (current since January 2017 amendment) 130.0 30.0  BBB or Baa2 110.0 20.0  BBB+ or Baa1 100.0 15.0  A- or A3 or higher 92.5 12.5  In January 2016, the Company obtained a $350 million unsecured term loan (“2016 Term Loan”), which matures in January 2019 with two one ‑year extension options. The interest rate for the term loan is currently 140 basis points over LIBOR, subject to adjustment on a sliding scale based on the Operating Partnership’s unsecured debt ratings, or, at the Company's option, a defined leverage ratio. The Company entered into interest rate swap arrangements to fix LIBOR for the duration of the term loan. Including costs, the current all-in fixed rate is 3.13 percent. The proceeds from the loan were used primarily to repay outstanding borrowings on the Company’s then existing unsecured revolving credit facility and to repay $200 million senior unsecured notes that matured on January 15, 2016 .  The interest rate on the 2016 Term Loan is based upon the Operating Partnership’s unsecured debt ratings, as follows:    Operating Partnership's Interest Rate -  Unsecured Debt Ratings: Applicable Basis Points  Higher of S&P or Moody's Above LIBOR  No ratings or less than BBB-/Baa3 185.0  BBB- or Baa3 (current interest rate based on Company's election) 140.0  BBB or Baa2 115.0  BBB+ or Baa1 100.0  A- or A3 or higher 90.0  If the Company elected to use the defined leverage ratio, the interest rate under the 2016 Term Loan would be based on the following total leverage ratio grid:     Interest Rate -  Applicable Basis  Total Leverage Ratio Points above LIBOR  < 45% 145.0  ≥ 45% and < 50% (current ratio) 155.0  ≥ 50% and < 55% 165.0  ≥ 55% 195.0  The terms of the 2016 Term Loan include certain restrictions and covenants which limit, among other things the incurrence of additional indebtedness, the incurrence of liens and the disposition of real estate properties (to the extent that: (i) such property dispositions cause the Company to default on any of the financial ratios of the term loan described below, or (ii) the property dispositions are completed while the Company is under an event of default under the term loan, unless, under certain circumstances, such disposition is being carried out to cure such default), and which require compliance with financial ratios relating to the maximum leverage ratio (60 percent), the maximum amount of secured indebtedness (40 percent), the minimum amount of fixed charge coverage (1.5 times), the maximum amount of unsecured indebtedness (60 percent), the minimum amount of unencumbered property interest coverage (2.0 times) and certain investment limitations (generally 15 percent of total capitalization). If an event of default has occurred and is continuing, the Company will not make any excess distributions except to enable the General Partner to continue to qualify as a REIT under the IRS Code.  The Company was in compliance with its debt covenants under its unsecured revolving credit facility and term loans as of December 31, 2017 .  As of December 31, 2017 and 2016 , the Company’s unsecured credit facility and term loans totaled $822.3 million and $634.1 million, respectively, comprised of: $150.0 million of outstanding borrowings under its unsecured revolving credit facility, $349.0 million from the 2016 Term Loan (net of unamortized deferred financing costs of $1.0 million) and $323.3 million from the 2017 Term Loan (net of unamortized deferred financing costs of $1.7 million) as of December 31, 2017, and $286 million of outstanding borrowings under its unsecured revolving credit facility and $348.1 from the 2016 Term Loan (net of unamortized deferred financing costs of $1.9 million) as of December 31, 2016.

Mortgages, Loans Payable And Ot

Mortgages, Loans Payable And Other Obligations	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Line Items]
Mortgages, Loans Payable And Other Obligations	9 . MORTGAGES, LOANS PAYABLE AND OTHER OBLIGATIONS  The Company has mortgages, loans payable and other obligations which primarily consist of various loans collateralized by certain of the Company’s rental properties, land and development projects. As of December 31, 2017 , 15 of the Company’s properties, with a total carrying value of approximately $ 1.6 b illion, and five of the Company’s land and development projects, with a total carrying value of approximately $435 million, are encumbered by the Company’s mortgages and loans payable. Payments on mortgages, loans payable and other obligations are generally due in monthly installments of principal and interest, or interest only. T he Company was in compliance with its debt covenants under its mortgages and loans payable as of December 31, 2017 .  A summary of the Company’s mortgages, loans payable and other obligations as of December 31, 2017 and 2016 is as follows: (dollars in thousands)    Effective December 31, December 31,  Property/Project Name Lender Rate (a) 2017 2016 Maturity  Curtis Center (b) CCRE & PREFG LIBOR+5.91 % - $ 75,000 -  Chase II (c) Fifth Third Bank LIBOR+2.25 % - 34,708 -  23 Main Street Berkadia CMBS 5.59 % $ 27,090 27,838 09/01/18  Port Imperial 4/5 Hotel (d) Fifth Third Bank & Santander LIBOR+4.50 % 43,674 14,919 10/06/18  Harborside Plaza 5 (e) The Northwestern Mutual Life Insurance Co. 6.84 % 209,257 213,640 11/01/18  & New York Life Insurance Co.  Insurance Co.  One River Center (f) Guardian Life Insurance Co. 7.31 % 40,485 41,197 02/01/19  Park Square Wells Fargo Bank N.A. LIBOR+1.87 % 26,567 27,500 04/10/19  250 Johnson (g) M&T Bank LIBOR+2.35 % 32,491 2,440 05/20/19  Portside 5/6 (h) Citizens Bank LIBOR+2.50 % 45,778 - 09/29/19  Port Imperial South 11 (i) JPMorgan Chase LIBOR+2.35 % 46,113 14,073 11/24/19  Worcester (j) Citizens Bank LIBOR+2.50 % 37,821 - 12/10/19  Monaco (k) The Northwestern Mutual Life Insurance Co. 3.15 % 169,987 - 02/01/21  Port Imperial South 4/5 Retail American General Life & A/G PC 4.56 % 4,000 4,000 12/01/21  The Chase at Overlook Ridge New York Community Bank 3.74 % - 72,500 02/01/23  Portside 7 CBRE Capital Markets/FreddieMac 3.57 % 58,998 58,998 08/01/23  Alterra I & II Capital One/FreddieMac 3.85 % 100,000 - 02/01/24  The Chase at Overlook Ridge and Chase II (c) New York Community Bank 3.74 % 135,750 - 01/01/25  101 Hudson Wells Fargo CMBS 3.20 % 250,000 250,000 10/11/26  Short Hills Portfolio (l) Wells Fargo CMBS 4.15 % 124,500 - 04/01/27  150 Main St. Natixis Real Estate Capital LLC 4.48 % 41,000 26,642 08/05/27  Port Imperial South 4/5 Garage American General Life & A/G PC 4.85 % 32,600 32,600 12/01/29   Principal balance outstanding 1,426,111 896,055  Unamortized deferred financing costs (7,976) (7,470)   Total mortgages, loans payable and other obligations, net $ 1,418,135 $ 888,585      (a) Reflects effective rate of debt, including deferred financing costs, comprised of the cost of terminated treasury lock agreements (if any), debt initiation costs,  mark-to-market adjustment of acquired debt and other transaction costs, as applicable.  (b) The Company owned a 50 percent tenants-in-common interest in the Curtis Center property. On September 29, 2017, the Company sold its equity interest to  its joint venture partner, which included the retirement of this $75 million loan balance.  (c) The Chase II construction loan was paid off on December 5, 2017 using the proceeds of a new combined mortgage loan secured by The Chase at Overlook Ridge  and Chase II.  (d) This construction loan has a maximum borrowing capacity of $94 million and provides, subject to certain conditions, two one -year extension options with a fee  of 20 basis points for each year. See Note 12: Commitments and Contingencies - Construction Projects.  (e) On January 8, 2018, the Company prepaid this loan in full upon payment of a fee of approximately $8.4 million using borrowings from the Company's  unsecured revolving credit facility.  (f) Mortgage is collateralized by the three properties comprising One River Center.  (g) This construction loan has a maximum borrowing capacity of $42 million and provides, subject to certain conditions, a one -year extension option with a fee  of 25 basis points. See Note 12: Commitments and Contingencies - Construction Projects.  (h) This construction loan has a maximum borrowing capacity of $73 million and provides, subject to certain conditions, two one -year extension options with a fee  of 15 basis points each year. See Note 12: Commitments and Contingencies - Construction Projects.  (i) This construction loan has a maximum borrowing capacity of $78 million and provides, subject to certain conditions, two one -year extension options with a fee  of 15 basis points each year. See Note 12: Commitments and Contingencies - Construction Projects.  (j) This construction loan has a maximum borrowing capacity of $58 million and provides, subject to certain conditions, two one -year extension options with a fee  of 15 basis points each year. See Note 12: Commitments and Contingencies - Construction Projects.  (k) This mortgage loan, which includes unamortized fair value adjustment of $5.0 million as of December 31, 2017, was assumed by the  Company in April 2017 with the consolidation of all the interests in Monaco Towers. See Note 3: Recent Transactions - Consolidations.  (l) This mortgage loan was obtained by the Company in March 2017 to partially fund the acquisition of the Short Hills/Madison portfolio.  SCHEDULED PRINCIPAL PAYMENTS Scheduled principal payments for the Company’s senior unsecured notes (see Note 7 ), unsecured revolving credit facility and term loan (see Note 8 ) and mortgages, loans payable and other obligations as of December 31, 2017 are as follows: (dollars in thousands)       Scheduled Principal  Period Amortization Maturities Total  2018 (a) $ 6,977 $ 275,210 $ 282,187  2019 665 576,489 577,154  2020 2,903 325,000 327,903  2021 3,227 318,800 322,027  2022 3,284 300,000 303,284  Thereafter 10,642 997,927 1,008,569  Sub-total 27,698 2,793,426 2,821,124  Adjustment for unamortized debt  discount/premium, net  December 31, 2017 (3,505) - (3,505)  Unamortized mark to market 4,987 - 4,987  Unamortized deferred financing costs (13,038) (13,038)   Totals/Weighted Average $ 16,142 $ 2,793,426 $ 2,809,568  (a) Includes a mortgage payable amount of approximately $209 million that the Company prepaid in January 2018.  CASH PAID FOR INTEREST AND INTEREST CAPITALIZED Cash paid for interest for the year s ended December 31, 2017 , 2016 and 2015 was $ 103,559,000 , $ 122,414,000 and $ 115,123,000 , respectively. Interest capitalized by the Company for the year s ended December 31, 2017 , 2016 and 2015 was $ 20,240,000 , $ 19,316,000 , and $ 16,217,000 , respectively (which amounts included $1,056,000 , $5,055,000 and $5,325,000 for the year s ended December 31, 2017 , 2016 and 2015 , respectively, o f interest capitalized on the Company’s investments in unconsolidated joint ventures which were substantially in development).  SUMMARY OF INDEBTEDNESS As of December 31, 2017 , the Company’s total indebtedness of $ 2,826,110,000 (weighted average interest rate of 3.93 percent) was comprised of $ 382,443,000 of unsecured revolving credit facility borrowings and other variable rate mortgage debt (weighted average rate of 3.63 percent) and fixed rate debt and other obligations of $ 2,443,667,000 (weighted average rate of 3.98 percent).  As of December 31, 2016 , the Company’s total indebtedness of $ 2,357,055,000 (weighted average interest rate of 3.79 percent) was comprised of $ 481,282,000 of unsecured revolving credit facility borrowings and other v ariable rate mortgage debt (weighted average rate of 2.93 percent) and fixed rate debt and other obligations of $ 1,875,773,000 (weighted average rate of 4.01 percent).
Mack-Cali Realty LP [Member]
Debt Disclosure [Line Items]
Mortgages, Loans Payable And Other Obligations	9 . MORTGAGES, LOANS PAYABLE AND OTHER OBLIGATIONS  The Company has mortgages, loans payable and other obligations which primarily consist of various loans collateralized by certain of the Company’s rental properties, land and development projects. As of December 31, 2017 , 15 of the Company’s properties, with a total carrying value of approximately $ 1.6 b illion, and five of the Company’s land and development projects, with a total carrying value of approximately $435 million, are encumbered by the Company’s mortgages and loans payable. Payments on mortgages, loans payable and other obligations are generally due in monthly installments of principal and interest, or interest only. T he Company was in compliance with its debt covenants under its mortgages and loans payable as of December 31, 2017 .  A summary of the Company’s mortgages, loans payable and other obligations as of December 31, 2017 and 2016 is as follows: (dollars in thousands)    Effective December 31, December 31,  Property/Project Name Lender Rate (a) 2017 2016 Maturity  Curtis Center (b) CCRE & PREFG LIBOR+5.91 % - $ 75,000 -  Chase II (c) Fifth Third Bank LIBOR+2.25 % - 34,708 -  23 Main Street Berkadia CMBS 5.59 % $ 27,090 27,838 09/01/18  Port Imperial 4/5 Hotel (d) Fifth Third Bank & Santander LIBOR+4.50 % 43,674 14,919 10/06/18  Harborside Plaza 5 (e) The Northwestern Mutual Life Insurance Co. 6.84 % 209,257 213,640 11/01/18  & New York Life Insurance Co.  Insurance Co.  One River Center (f) Guardian Life Insurance Co. 7.31 % 40,485 41,197 02/01/19  Park Square Wells Fargo Bank N.A. LIBOR+1.87 % 26,567 27,500 04/10/19  250 Johnson (g) M&T Bank LIBOR+2.35 % 32,491 2,440 05/20/19  Portside 5/6 (h) Citizens Bank LIBOR+2.50 % 45,778 - 09/29/19  Port Imperial South 11 (i) JPMorgan Chase LIBOR+2.35 % 46,113 14,073 11/24/19  Worcester (j) Citizens Bank LIBOR+2.50 % 37,821 - 12/10/19  Monaco (k) The Northwestern Mutual Life Insurance Co. 3.15 % 169,987 - 02/01/21  Port Imperial South 4/5 Retail American General Life & A/G PC 4.56 % 4,000 4,000 12/01/21  The Chase at Overlook Ridge New York Community Bank 3.74 % - 72,500 02/01/23  Portside 7 CBRE Capital Markets/FreddieMac 3.57 % 58,998 58,998 08/01/23  Alterra I & II Capital One/FreddieMac 3.85 % 100,000 - 02/01/24  The Chase at Overlook Ridge and Chase II (c) New York Community Bank 3.74 % 135,750 - 01/01/25  101 Hudson Wells Fargo CMBS 3.20 % 250,000 250,000 10/11/26  Short Hills Portfolio (l) Wells Fargo CMBS 4.15 % 124,500 - 04/01/27  150 Main St. Natixis Real Estate Capital LLC 4.48 % 41,000 26,642 08/05/27  Port Imperial South 4/5 Garage American General Life & A/G PC 4.85 % 32,600 32,600 12/01/29   Principal balance outstanding 1,426,111 896,055  Unamortized deferred financing costs (7,976) (7,470)   Total mortgages, loans payable and other obligations, net $ 1,418,135 $ 888,585      (a) Reflects effective rate of debt, including deferred financing costs, comprised of the cost of terminated treasury lock agreements (if any), debt initiation costs,  mark-to-market adjustment of acquired debt and other transaction costs, as applicable.  (b) The Company owned a 50 percent tenants-in-common interest in the Curtis Center property. On September 29, 2017, the Company sold its equity interest to  its joint venture partner, which included the retirement of this $75 million loan balance.  (c) The Chase II construction loan was paid off on December 5, 2017 using the proceeds of a new combined mortgage loan secured by The Chase at Overlook Ridge  and Chase II.  (d) This construction loan has a maximum borrowing capacity of $94 million and provides, subject to certain conditions, two one -year extension options with a fee  of 20 basis points for each year. See Note 12: Commitments and Contingencies - Construction Projects.  (e) On January 8, 2018, the Company prepaid this loan in full upon payment of a fee of approximately $8.4 million using borrowings from the Company's  unsecured revolving credit facility.  (f) Mortgage is collateralized by the three properties comprising One River Center.  (g) This construction loan has a maximum borrowing capacity of $42 million and provides, subject to certain conditions, a one -year extension option with a fee  of 25 basis points. See Note 12: Commitments and Contingencies - Construction Projects.  (h) This construction loan has a maximum borrowing capacity of $73 million and provides, subject to certain conditions, two one -year extension options with a fee  of 15 basis points each year. See Note 12: Commitments and Contingencies - Construction Projects.  (i) This construction loan has a maximum borrowing capacity of $78 million and provides, subject to certain conditions, two one -year extension options with a fee  of 15 basis points each year. See Note 12: Commitments and Contingencies - Construction Projects.  (j) This construction loan has a maximum borrowing capacity of $58 million and provides, subject to certain conditions, two one -year extension options with a fee  of 15 basis points each year. See Note 12: Commitments and Contingencies - Construction Projects.  (k) This mortgage loan, which includes unamortized fair value adjustment of $5.0 million as of December 31, 2017, was assumed by the  Company in April 2017 with the consolidation of all the interests in Monaco Towers. See Note 3: Recent Transactions - Consolidations.  (l) This mortgage loan was obtained by the Company in March 2017 to partially fund the acquisition of the Short Hills/Madison portfolio.  SCHEDULED PRINCIPAL PAYMENTS Scheduled principal payments for the Company’s senior unsecured notes (see Note 7 ), unsecured revolving credit facility and term loan (see Note 8 ) and mortgages, loans payable and other obligations as of December 31, 2017 are as follows: (dollars in thousands)       Scheduled Principal  Period Amortization Maturities Total  2018 (a) $ 6,977 $ 275,210 $ 282,187  2019 665 576,489 577,154  2020 2,903 325,000 327,903  2021 3,227 318,800 322,027  2022 3,284 300,000 303,284  Thereafter 10,642 997,927 1,008,569  Sub-total 27,698 2,793,426 2,821,124  Adjustment for unamortized debt  discount/premium, net  December 31, 2017 (3,505) - (3,505)  Unamortized mark to market 4,987 - 4,987  Unamortized deferred financing costs (13,038) (13,038)   Totals/Weighted Average $ 16,142 $ 2,793,426 $ 2,809,568  (a) Includes a mortgage payable amount of approximately $209 million that the Company prepaid in January 2018.  CASH PAID FOR INTEREST AND INTEREST CAPITALIZED Cash paid for interest for the year s ended December 31, 2017 , 2016 and 2015 was $ 103,559,000 , $ 122,414,000 and $ 115,123,000 , respectively. Interest capitalized by the Company for the year s ended December 31, 2017 , 2016 and 2015 was $ 20,240,000 , $ 19,316,000 , and $ 16,217,000 , respectively (which amounts included $1,056,000 , $5,055,000 and $5,325,000 for the year s ended December 31, 2017 , 2016 and 2015 , respectively, o f interest capitalized on the Company’s investments in unconsolidated joint ventures which were substantially in development).  SUMMARY OF INDEBTEDNESS As of December 31, 2017 , the Company’s total indebtedness of $ 2,826,110,000 (weighted average interest rate of 3.93 percent) was comprised of $ 382,443,000 of unsecured revolving credit facility borrowings and other variable rate mortgage debt (weighted average rate of 3.63 percent) and fixed rate debt and other obligations of $ 2,443,667,000 (weighted average rate of 3.98 percent).  As of December 31, 2016 , the Company’s total indebtedness of $ 2,357,055,000 (weighted average interest rate of 3.79 percent) was comprised of $ 481,282,000 of unsecured revolving credit facility borrowings and other v ariable rate mortgage debt (weighted average rate of 2.93 percent) and fixed rate debt and other obligations of $ 1,875,773,000 (weighted average rate of 4.01 percent).

Employee Benefit 401(k) Plans

Employee Benefit 401(k) Plans	12 Months Ended
	Dec. 31, 2017
Compensation And Retirement Disclosure [Line Items]
Employee Benefit 401(k) Plans	1 0 . EMPLOYEE BENEFIT 401(k) PLANS  Employees of the General Partner , who meet certain minimum age and service requirements, are eligible to participate in the Mack-Cali Realty Corporation 401(k) Savings/Retirement Plan (the “401(k) Plan”). Eligible employees may elect to defer from one percent up to 60 percent of their annual compensation on a pre-tax basis to the 401(k) Plan, subject to certain limitations imposed by federal law. The amounts contributed by employees are immediately vested and non-forfeitable. The Company may make discretionary matching or profit sharing contributions to the 401(k) Plan on behalf of eligibl e participants in any plan year. Participants are always 100 percent vested in their pre-tax contributions and will begin vesting in any matching or profit sharing contributions made on their behalf after two years of service with the Company at a rate of 20 percent per year, becoming 100 percent vested after a total of six years of service with the Company. All contributions are allocated as a percentage of compensation of the eligible participants for the Plan year. The assets of the 401(k) Plan are held in trust and a separate account is established for each participant. A participant may receive a distribution of his or her vested account balance in the 401(k) Plan in a single sum or in installment payments upon his or her termination of service with the Company. Total expense recognized by the Company for the 401(k) Plan for the years ended December 31, 2017 , 2016 and 2015 was $ 1,055,000 , $ 1,029,000 and $ 970,000 , respectively .
Mack-Cali Realty LP [Member]
Compensation And Retirement Disclosure [Line Items]
Employee Benefit 401(k) Plans	1 0 . EMPLOYEE BENEFIT 401(k) PLANS  Employees of the General Partner , who meet certain minimum age and service requirements, are eligible to participate in the Mack-Cali Realty Corporation 401(k) Savings/Retirement Plan (the “401(k) Plan”). Eligible employees may elect to defer from one percent up to 60 percent of their annual compensation on a pre-tax basis to the 401(k) Plan, subject to certain limitations imposed by federal law. The amounts contributed by employees are immediately vested and non-forfeitable. The Company may make discretionary matching or profit sharing contributions to the 401(k) Plan on behalf of eligibl e participants in any plan year. Participants are always 100 percent vested in their pre-tax contributions and will begin vesting in any matching or profit sharing contributions made on their behalf after two years of service with the Company at a rate of 20 percent per year, becoming 100 percent vested after a total of six years of service with the Company. All contributions are allocated as a percentage of compensation of the eligible participants for the Plan year. The assets of the 401(k) Plan are held in trust and a separate account is established for each participant. A participant may receive a distribution of his or her vested account balance in the 401(k) Plan in a single sum or in installment payments upon his or her termination of service with the Company. Total expense recognized by the Company for the 401(k) Plan for the years ended December 31, 2017 , 2016 and 2015 was $ 1,055,000 , $ 1,029,000 and $ 970,000 , respectively .

Disclosure Of Fair Value Of Ass

Disclosure Of Fair Value Of Assets And Liabilities	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Line Items]
Disclosure Of Fair Value Of Assets And Liabilities	11. DISCLOSURE OF FAIR VALUE OF ASSETS AND LIABILITIES  The following disclosure of estimated fair value was determined by management using available market information and appropriate valuation methodologies. However, considerable judgment is necessary to interpret market data and develop estimated fair value. Accordingly, the estimates presented herein are not necessarily indicative of the amounts the Company could realize on disposition of the assets and liabilities at December 31, 2017 and 2016 . The use of different market assumptions and/or estimation methodologies may have a material effect on the estimated fair value amounts.  Cash equivalents, receivables, notes receivables, accounts payable, and accrued expenses and other liabilities are carried at amounts which reasonably approximate their fair values as of December 31, 2017 and 2016 .  The fair value of the Company’s long-term debt, consisting of senior unsecured notes , unsecured term loans, an unsecured revolving credit facility and mortgages, loans payable and other obligations aggregate d approximately $ 2,764,033,000 and $ 2,308,488,000 a s compared to the book value of approximately $ 2,809,568,000 and $ 2,340,009,000 as of December 31, 2017 and 2016 , respectively. The fair value of the Company’s long-term debt was categorized as a level 3 basis (as provided by ASC 820, Fair Value Measurements and Disclosures) . The fair value was estimated using a discounted cash flow analysis valuation based on the borrowing rates currently available to the Company for loans with similar terms and maturities. The fair value of the mortgage debt and the unsecured notes was determined by discounting the future contractual interest and principal payments by a market rate. Although the Company has determined that the majority of the inputs used to value its derivative financial instruments fall within level 2 of the fair value hierarchy, the credit valuation adjustments associated with its derivative financial instruments utilize level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default by itself and its counterparties. The Company has assessed the significance of the impact of the credit valuation adjustments on the overall valuation of its derivative positions and has determined that the credit valuation adjustments are not significant to the overall valuation of its derivative financial instruments. As a result, the Company has determined that its derivative financial instruments valuations in their entirety are classified in level 2 of the fair value hierarchy.  The fair value measurements used in the evaluation of the Company’s rental properties are considered to be Level 3 valuations within the fair value hierarchy, as there are significant unobservable inputs. Examples of inputs that were utilized in the fair value calculations include estimated holding periods, discount rates, market capitalization rates, expected lease rental rates, and third party broker information.  Valuations of rental property identified as held for sale are based on estimated sale prices, net of estimated selling costs, of such property.  The Company identified as held for sale 21 office properties as of December 31, 2017 with an aggregate carrying value of $171.6 million. The total estimated sales proceeds from the sales are expected to be approximately $223 million. The Company determined that the carrying value of seven of the se properties was not expected to be recovered from estimated net sales proceeds and accordingly recognized an unrealized loss allowance of $12.3 million during the year ended December 31, 2017.  The Company identified as held for sale eight office properties as of December 31, 2016 with an aggregate carrying value of $39.7 million. The total estimated sales proceeds from the sales were expected to be approximately $49 million. The Company determined that the carrying value of one of these properties was not expected to be recovered from estimated net sales proceeds and accordingly recognized an unrealized loss allowance of $7.7 million at December 31, 2016.  Disclosure about fair value of assets and liabilities is based on pertinent information available to management as of December 31, 2017 and 2016 . Although management is not aware of any factors that would significantly affect the fair value amounts, such amounts have not been comprehensively revalued for purposes of these financial statements since December 31, 2017 and current estimates of fair value may differ significantly from the amounts presented herein.
Mack-Cali Realty LP [Member]
Fair Value Disclosures [Line Items]
Disclosure Of Fair Value Of Assets And Liabilities	11. DISCLOSURE OF FAIR VALUE OF ASSETS AND LIABILITIES  The following disclosure of estimated fair value was determined by management using available market information and appropriate valuation methodologies. However, considerable judgment is necessary to interpret market data and develop estimated fair value. Accordingly, the estimates presented herein are not necessarily indicative of the amounts the Company could realize on disposition of the assets and liabilities at December 31, 2017 and 2016 . The use of different market assumptions and/or estimation methodologies may have a material effect on the estimated fair value amounts.  Cash equivalents, receivables, notes receivables, accounts payable, and accrued expenses and other liabilities are carried at amounts which reasonably approximate their fair values as of December 31, 2017 and 2016 .  The fair value of the Company’s long-term debt, consisting of senior unsecured notes , unsecured term loans, an unsecured revolving credit facility and mortgages, loans payable and other obligations aggregate d approximately $ 2,764,033,000 and $ 2,308,488,000 a s compared to the book value of approximately $ 2,809,568,000 and $ 2,340,009,000 as of December 31, 2017 and 2016 , respectively. The fair value of the Company’s long-term debt was categorized as a level 3 basis (as provided by ASC 820, Fair Value Measurements and Disclosures) . The fair value was estimated using a discounted cash flow analysis valuation based on the borrowing rates currently available to the Company for loans with similar terms and maturities. The fair value of the mortgage debt and the unsecured notes was determined by discounting the future contractual interest and principal payments by a market rate. Although the Company has determined that the majority of the inputs used to value its derivative financial instruments fall within level 2 of the fair value hierarchy, the credit valuation adjustments associated with its derivative financial instruments utilize level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default by itself and its counterparties. The Company has assessed the significance of the impact of the credit valuation adjustments on the overall valuation of its derivative positions and has determined that the credit valuation adjustments are not significant to the overall valuation of its derivative financial instruments. As a result, the Company has determined that its derivative financial instruments valuations in their entirety are classified in level 2 of the fair value hierarchy.  The fair value measurements used in the evaluation of the Company’s rental properties are considered to be Level 3 valuations within the fair value hierarchy, as there are significant unobservable inputs. Examples of inputs that were utilized in the fair value calculations include estimated holding periods, discount rates, market capitalization rates, expected lease rental rates, and third party broker information.  Valuations of rental property identified as held for sale are based on estimated sale prices, net of estimated selling costs, of such property.  The Company identified as held for sale 21 office properties as of December 31, 2017 with an aggregate carrying value of $171.6 million. The total estimated sales proceeds from the sales are expected to be approximately $223 million. The Company determined that the carrying value of seven of the se properties was not expected to be recovered from estimated net sales proceeds and accordingly recognized an unrealized loss allowance of $12.3 million during the year ended December 31, 2017.  The Company identified as held for sale eight office properties as of December 31, 2016 with an aggregate carrying value of $39.7 million. The total estimated sales proceeds from the sales were expected to be approximately $49 million. The Company determined that the carrying value of one of these properties was not expected to be recovered from estimated net sales proceeds and accordingly recognized an unrealized loss allowance of $7.7 million at December 31, 2016.  Disclosure about fair value of assets and liabilities is based on pertinent information available to management as of December 31, 2017 and 2016 . Although management is not aware of any factors that would significantly affect the fair value amounts, such amounts have not been comprehensively revalued for purposes of these financial statements since December 31, 2017 and current estimates of fair value may differ significantly from the amounts presented herein.

Commitments And Contingencies

Commitments And Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments And Contingencies [Line Items]
Commitments And Contingencies	12. COMMITMENTS AND CONTINGENCIES  TAX ABATEMENT AGREEMENTS Pursuant to agreements with certain municipalities, the Company is required to make payments in lieu of property taxes (“PILOT”) on certain of its properties and has tax abatement agreements on other properties, as follows:  The Harborside Plaza 4-A agreement with the City of Jersey City, as amended, which commenced in 2002, is for a term of 20 years. The annual PILOT is equal to two percent of Total Project Costs, as defined. Total Project Costs are $ 49.5 million. The PILOT totaled $ 1.1 million, $1.1 million and $ 990,000 for the years ended December 31, 2017 , 2016 and 2015 , respectively.  The Harborside Plaza 5 agreement, also with the City of Jersey City, as amended, which commenced in 2002, is for a term of 20 years. The annual PILOT is equal to two percent of Total Project Costs, as defined. Total Project Costs are $ 170.9 million. The PILOT totaled $ 3.9 million, $ 3.9 million and $ 3.4 million for the years ended December 31, 2017 , 2016 and 2015 , respectively.  The Port Imperial 4/5 Garage development project agreement with the City of Weehawken has a term of five years beginning when the project is substantially complete, which occurred in the third quarter of 2013. The agreement provides that real estate taxes be paid initially on the land value of the project only and allows for a phase in of real estate taxes on the value of the improvements at zero percent year one and 80 percent in years two through five.  The Port Imperial South 1/3 Garage development project agreement with the City of Weehawken has a term of five years beginning when the project is substantially complete, which occurred in the fourth quarter of 2015. The agreement provides that real estate taxes be paid at 100 percent on the land value of the project only over the five year period and allows for a phase in of real estate taxes on the building improvement value at zero percent in year one and 95 percent in years two through five.  The Port Imperial Hotel development project agreement with the City of Weehawken is for a term of 15 years following substantial completion, which is anticipated to be in the s econd quarter 2018. The annual PILOT is equal to two percent of Total Project Costs, as defined.  The Port Imperial South 11 development project agreement with the City of Weehawken is for a term of 15 years following substantial completion, which is anticipated to be in the first quarter 2018. The annual PILOT is equal to 10 percent of Gross Revenues, as defined.  The 111 River Realty agreement with the City of Hoboken, which commenced on October 1, 2001 expires in April 2022. The PILOT payment equals $1,227,708 annually through April 2017 and then increases to $1,406,064 annually until expiration. The PILOT totaled $1.3 million and $0.6 million for the year ended December 31, 2017 and 2016, respectively.  The Monaco Towers agreement with the City of Jersey City, which commenced in 2011, is for a term of 10 years. The annual PILOT is equal to 10 percent of gross revenues, as defined. The PILOT totaled $1,643,522 for the period from acquisition (April 2017) through December 31, 2017.  At the conclusion of the above-referenced agreements, it is expected that the properties will be assessed by the municipality and be subject to real estate taxes at the then prevailing rates.  LITIGATION The Company is a defendant in litigation arising in the normal course of its business activities. Management does not believe that the ultimate resolution of these matters will have a materially adverse effect upon the Company’s financial condition taken as whole.  GROUND LEASE AGREEMENTS Future minimum rental payments under the terms of all non-cancelable ground leases under which the Company is the lessee, as of December 31, 2017 , are as follows: (dollars in thousands)    Year Amount  2018 $ 2,465  2019 2,471  2020 2,487  2021 2,487  2022 2,487  2023 through 2084 212,534   Total $ 224,931  Ground lease expense incurred by the Company during the years ended December 31, 2017 , 2016 and 2015 amounted to $ 2.6 million, $ 1.5 million and $406,000 , respectively.  CONSTRUCTION PROJECTS In 2015, the Company commenced development of a two-phase multi-family development of the CitySquare project in Worcester, Massachusetts. The first phase, with 237 units, is under construction with anticipated initial deliveries in the first quarter 2018 . The second phase, with 128 units, started construction in the third quarter 2016 with anticipated initial deliveries in the third quarter 2018 . Total development costs for both phases are estimated to be $92.7 million with development costs of $86.9 million incurred through December 31, 201 7 . The Company has a construction loan with a maximum borrowing amount of $58 million (with $37.8 million outstanding as of December 31, 2017 ) , which is expected to fund the remaining costs to complete the project .  In 2015, the Company entered into a 90 -percent owned consolidated joint venture with XS Port Imperial Hotel, LLC to form XS Hotel Urban Renewal Associates LLC, which is developing a 372 -key hotel in Weehawken, New Jersey. The project is expected to be ready for occupancy by second quarter 2018 . The construction of the project is estimated to cost $139.4 million, with development costs of $101.7 million incurred by the venture through December 31, 201 7 . The venture has a $94 million construction loan (with $43.7 million outstanding as of December 31, 2017 ) , which is expected to fund the remaining costs to complete the project .  In 2016, the Company commenced the repurposing of a former office property site located at 250 Johnson Road in Morris Plains, New Jersey into a 197 -unit multi-family development project. The project, which is estimated to cost $58.7 million ( of which development costs of 53.9 million have been incurred through December 31, 2017 ), is expected to be ready for occupancy by the first quarter 2018 . The remaining costs to complete the project are expected to be funded primarily from a $42 million construction loan (with $32.5 million outstanding as of December 31, 2017).  In 2016, the Company started construction of a 296 -unit multi-family project known as Portside 5/6 in East Boston, Massachusetts. The project is expected to be ready for occupancy by second quarter 2018 and is estimated to cost $111.4 million (of which $101.3 million have been incurred through December 31, 2017). The remaining costs to complete the project are expected to be funded primarily from a $73 million construction loan (with $45.8 million outstanding as of December 31, 2017) .  The Company is developing a 295 -unit multi-family project in Weehawken, New Jersey, which began construction in first quarter 2016. The project, known as Port Imperial South 11, which is expected to be ready for occupancy by second quarter 2018 , is estimated to cost $125 million (of which development costs of $83.6 million have been incurred through December 31, 2017 ). The project costs are expected to be funded from a $78 million construction loan (with $46.1 million outstanding as of December 31, 2017). The Company expects to fund $47 million for the development of the project, of which the Company has funded $37.5 million as of December 31, 201 7 .  CHANGES IN EXECUTIVE OFFICERS On January 29, 2018, the Company announced the appointment of David J. Smetana as chief financial officer and Nicholas Hilton as executive vice president of leasing of the General Partner. Mr. Smetana will begin to perform his duties as chief financial officer and Anthony Krug shall cease to serve as chief financial officer immediately following the filing of this Annual Report on Form 10-K for the year ended December 31, 2017. Mr. Krug will remain an employee of the General Partner and will provide transition services through March 31, 2018. Mr. Hilton’s employment commenced on February 12, 2018 following the departure of Christopher DeLorenzo. In connection with these management changes, on January 26, 2018, the General Partner entered into a separation agreement and release with each of Messrs. Krug and DeLorenzo. Under the terms of the Krug s eparation a greement, Mr. Krug will receive the following severance benefits: · Earned but unpaid compensation through the date of termination, including base salary, 2017 bonus (when determined), a pro rata portion of his annual car allowance, and any unused vacation time; · A lump sum cash severance payment of $1,312,500 ; · A prorated portion of his 2018 target bonus equal to $93,750 ; · COBRA payments for up to two years after termination, in an amount equal to approximately $42,000 ; and · Accelerated vesting of all unvested LTIP units in the Operating Partnership , consisting of 13,306 LTIP units subject to time-based vesting and 18,665 LTIP units subject to performance-based vesting, with LTIP units subject to performance-based vesting criteria vesting at target performance.  Under the terms of the DeLorenzo s eparation a greement, Mr. DeLorenzo will receive the following severance benefits: · Earned but unpaid compensation through the date of termination, including base salary, 2017 bonus (when determined), a pro rata portion of his annual car allowance, and any unused vacation time; · A lump sum cash severance payment of $500,000 ; · COBRA payments for up to 18 months after termination, in an amount equal to approximately $42,000 ; and · Partial accelerated vesting of unvested LTIP units in the Operating Partnership , consisting of 9,111 LTIP units subject to time based vesting and 13,982 LTIP units subject to performance-based vesting, with LTIP units subject to performance based vesting criteria vesting at target performance.  OTHER Through February 2016, the Company could not dispose of or distribute certain of its properties, which were originally contributed by certain unrelated common unitholders of the Operating Partnership , without the express written consent of such common unitholders, as applicable, except in a manner which did not result in recognition of any built-in-gain (which may result in an income tax liability) or which reimbursed the appropriate specific common unitholders for the tax consequences of the recognition of such built-in-gains (collectively, the “Property Lock-Ups”). Upon the expiration in February 2016 of the Property Lock-Ups, the Company is generally required to use commercially reasonable efforts to prevent any sale, transfer or other disposition of the subject properties from resulting in the recognition of built-in gain to the specific common unitholders, which include members of the Mack Group (which includes William L. Mack, Chairman of the General Partner’s Board of Directors; David S. Mack, director; and Earle I. Mack, a former director), the Robert Martin Group (which includes Robert F. Weinberg, a former director and current member of the General Partner's Advisory Board), and the Cali Group (which includes John R. Cali, a former director and current member of the General Partner's Advisory Board). As of December 31, 2017, 80 of the Company’s properties, primarily a portfolio of flex properties in Westchester County, New York with an aggregate carrying value of approximately $ 1.0 billion, are subject to these conditions.  In August 2017, the Company acquired an existing mortgage note receivable encumbering a vacant developable land parcel located in Jersey City, New Jersey (the “Land Property”) with a balance of $44.7 million (the “Land Note Receivable”). The Land Note Receivable matures in July 2019 and earns interest at an annual rate of 5.85 percent which accrues monthly and is payable at maturity. The Land Property is currently an unimproved land parcel which operates as a surface parking facility. Additionally, the Company entered into an agreement to acquire the Land Property, subject to the Company's ability to obtain all necessary development rights and entitlements to develop an apartment building on the land, and other related conditions to ensure that the Company can develop the project. The purchase price is $73 million, subject to adjustment based on the level of development rights obtained for the construction of a multifamily apartment building.
Mack-Cali Realty LP [Member]
Commitments And Contingencies [Line Items]
Commitments And Contingencies	12. COMMITMENTS AND CONTINGENCIES  TAX ABATEMENT AGREEMENTS Pursuant to agreements with certain municipalities, the Company is required to make payments in lieu of property taxes (“PILOT”) on certain of its properties and has tax abatement agreements on other properties, as follows:  The Harborside Plaza 4-A agreement with the City of Jersey City, as amended, which commenced in 2002, is for a term of 20 years. The annual PILOT is equal to two percent of Total Project Costs, as defined. Total Project Costs are $ 49.5 million. The PILOT totaled $ 1.1 million, $1.1 million and $ 990,000 for the years ended December 31, 2017 , 2016 and 2015 , respectively.  The Harborside Plaza 5 agreement, also with the City of Jersey City, as amended, which commenced in 2002, is for a term of 20 years. The annual PILOT is equal to two percent of Total Project Costs, as defined. Total Project Costs are $ 170.9 million. The PILOT totaled $ 3.9 million, $ 3.9 million and $ 3.4 million for the years ended December 31, 2017 , 2016 and 2015 , respectively.  The Port Imperial 4/5 Garage development project agreement with the City of Weehawken has a term of five years beginning when the project is substantially complete, which occurred in the third quarter of 2013. The agreement provides that real estate taxes be paid initially on the land value of the project only and allows for a phase in of real estate taxes on the value of the improvements at zero percent year one and 80 percent in years two through five.  The Port Imperial South 1/3 Garage development project agreement with the City of Weehawken has a term of five years beginning when the project is substantially complete, which occurred in the fourth quarter of 2015. The agreement provides that real estate taxes be paid at 100 percent on the land value of the project only over the five year period and allows for a phase in of real estate taxes on the building improvement value at zero percent in year one and 95 percent in years two through five.  The Port Imperial Hotel development project agreement with the City of Weehawken is for a term of 15 years following substantial completion, which is anticipated to be in the s econd quarter 2018. The annual PILOT is equal to two percent of Total Project Costs, as defined.  The Port Imperial South 11 development project agreement with the City of Weehawken is for a term of 15 years following substantial completion, which is anticipated to be in the first quarter 2018. The annual PILOT is equal to 10 percent of Gross Revenues, as defined.  The 111 River Realty agreement with the City of Hoboken, which commenced on October 1, 2001 expires in April 2022. The PILOT payment equals $1,227,708 annually through April 2017 and then increases to $1,406,064 annually until expiration. The PILOT totaled $1.3 million and $0.6 million for the year ended December 31, 2017 and 2016, respectively.  The Monaco Towers agreement with the City of Jersey City, which commenced in 2011, is for a term of 10 years. The annual PILOT is equal to 10 percent of gross revenues, as defined. The PILOT totaled $1,643,522 for the period from acquisition (April 2017) through December 31, 2017.  At the conclusion of the above-referenced agreements, it is expected that the properties will be assessed by the municipality and be subject to real estate taxes at the then prevailing rates.  LITIGATION The Company is a defendant in litigation arising in the normal course of its business activities. Management does not believe that the ultimate resolution of these matters will have a materially adverse effect upon the Company’s financial condition taken as whole.  GROUND LEASE AGREEMENTS Future minimum rental payments under the terms of all non-cancelable ground leases under which the Company is the lessee, as of December 31, 2017 , are as follows: (dollars in thousands)    Year Amount  2018 $ 2,465  2019 2,471  2020 2,487  2021 2,487  2022 2,487  2023 through 2084 212,534   Total $ 224,931  Ground lease expense incurred by the Company during the years ended December 31, 2017 , 2016 and 2015 amounted to $ 2.6 million, $ 1.5 million and $406,000 , respectively.  CONSTRUCTION PROJECTS In 2015, the Company commenced development of a two-phase multi-family development of the CitySquare project in Worcester, Massachusetts. The first phase, with 237 units, is under construction with anticipated initial deliveries in the first quarter 2018 . The second phase, with 128 units, started construction in the third quarter 2016 with anticipated initial deliveries in the third quarter 2018 . Total development costs for both phases are estimated to be $92.7 million with development costs of $86.9 million incurred through December 31, 201 7 . The Company has a construction loan with a maximum borrowing amount of $58 million (with $37.8 million outstanding as of December 31, 2017 ) , which is expected to fund the remaining costs to complete the project .  In 2015, the Company entered into a 90 -percent owned consolidated joint venture with XS Port Imperial Hotel, LLC to form XS Hotel Urban Renewal Associates LLC, which is developing a 372 -key hotel in Weehawken, New Jersey. The project is expected to be ready for occupancy by second quarter 2018 . The construction of the project is estimated to cost $139.4 million, with development costs of $101.7 million incurred by the venture through December 31, 201 7 . The venture has a $94 million construction loan (with $43.7 million outstanding as of December 31, 2017 ) , which is expected to fund the remaining costs to complete the project .  In 2016, the Company commenced the repurposing of a former office property site located at 250 Johnson Road in Morris Plains, New Jersey into a 197 -unit multi-family development project. The project, which is estimated to cost $58.7 million ( of which development costs of 53.9 million have been incurred through December 31, 2017 ), is expected to be ready for occupancy by the first quarter 2018 . The remaining costs to complete the project are expected to be funded primarily from a $42 million construction loan (with $32.5 million outstanding as of December 31, 2017).  In 2016, the Company started construction of a 296 -unit multi-family project known as Portside 5/6 in East Boston, Massachusetts. The project is expected to be ready for occupancy by second quarter 2018 and is estimated to cost $111.4 million (of which $101.3 million have been incurred through December 31, 2017). The remaining costs to complete the project are expected to be funded primarily from a $73 million construction loan (with $45.8 million outstanding as of December 31, 2017) .  The Company is developing a 295 -unit multi-family project in Weehawken, New Jersey, which began construction in first quarter 2016. The project, known as Port Imperial South 11, which is expected to be ready for occupancy by second quarter 2018 , is estimated to cost $125 million (of which development costs of $83.6 million have been incurred through December 31, 2017 ). The project costs are expected to be funded from a $78 million construction loan (with $46.1 million outstanding as of December 31, 2017). The Company expects to fund $47 million for the development of the project, of which the Company has funded $37.5 million as of December 31, 201 7 .  CHANGES IN EXECUTIVE OFFICERS On January 29, 2018, the Company announced the appointment of David J. Smetana as chief financial officer and Nicholas Hilton as executive vice president of leasing of the General Partner. Mr. Smetana will begin to perform his duties as chief financial officer and Anthony Krug shall cease to serve as chief financial officer immediately following the filing of this Annual Report on Form 10-K for the year ended December 31, 2017. Mr. Krug will remain an employee of the General Partner and will provide transition services through March 31, 2018. Mr. Hilton’s employment commenced on February 12, 2018 following the departure of Christopher DeLorenzo. In connection with these management changes, on January 26, 2018, the General Partner entered into a separation agreement and release with each of Messrs. Krug and DeLorenzo. Under the terms of the Krug s eparation a greement, Mr. Krug will receive the following severance benefits: · Earned but unpaid compensation through the date of termination, including base salary, 2017 bonus (when determined), a pro rata portion of his annual car allowance, and any unused vacation time; · A lump sum cash severance payment of $1,312,500 ; · A prorated portion of his 2018 target bonus equal to $93,750 ; · COBRA payments for up to two years after termination, in an amount equal to approximately $42,000 ; and · Accelerated vesting of all unvested LTIP units in the Operating Partnership , consisting of 13,306 LTIP units subject to time-based vesting and 18,665 LTIP units subject to performance-based vesting, with LTIP units subject to performance-based vesting criteria vesting at target performance.  Under the terms of the DeLorenzo s eparation a greement, Mr. DeLorenzo will receive the following severance benefits: · Earned but unpaid compensation through the date of termination, including base salary, 2017 bonus (when determined), a pro rata portion of his annual car allowance, and any unused vacation time; · A lump sum cash severance payment of $500,000 ; · COBRA payments for up to 18 months after termination, in an amount equal to approximately $42,000 ; and · Partial accelerated vesting of unvested LTIP units in the Operating Partnership , consisting of 9,111 LTIP units subject to time based vesting and 13,982 LTIP units subject to performance-based vesting, with LTIP units subject to performance based vesting criteria vesting at target performance.  OTHER Through February 2016, the Company could not dispose of or distribute certain of its properties, which were originally contributed by certain unrelated common unitholders of the Operating Partnership , without the express written consent of such common unitholders, as applicable, except in a manner which did not result in recognition of any built-in-gain (which may result in an income tax liability) or which reimbursed the appropriate specific common unitholders for the tax consequences of the recognition of such built-in-gains (collectively, the “Property Lock-Ups”). Upon the expiration in February 2016 of the Property Lock-Ups, the Company is generally required to use commercially reasonable efforts to prevent any sale, transfer or other disposition of the subject properties from resulting in the recognition of built-in gain to the specific common unitholders, which include members of the Mack Group (which includes William L. Mack, Chairman of the General Partner’s Board of Directors; David S. Mack, director; and Earle I. Mack, a former director), the Robert Martin Group (which includes Robert F. Weinberg, a former director and current member of the General Partner's Advisory Board), and the Cali Group (which includes John R. Cali, a former director and current member of the General Partner's Advisory Board). As of December 31, 2017, 80 of the Company’s properties, primarily a portfolio of flex properties in Westchester County, New York with an aggregate carrying value of approximately $ 1.0 billion, are subject to these conditions.  In August 2017, the Company acquired an existing mortgage note receivable encumbering a vacant developable land parcel located in Jersey City, New Jersey (the “Land Property”) with a balance of $44.7 million (the “Land Note Receivable”). The Land Note Receivable matures in July 2019 and earns interest at an annual rate of 5.85 percent which accrues monthly and is payable at maturity. The Land Property is currently an unimproved land parcel which operates as a surface parking facility. Additionally, the Company entered into an agreement to acquire the Land Property, subject to the Company's ability to obtain all necessary development rights and entitlements to develop an apartment building on the land, and other related conditions to ensure that the Company can develop the project. The purchase price is $73 million, subject to adjustment based on the level of development rights obtained for the construction of a multifamily apartment building.

Tenant Leases

Tenant Leases	12 Months Ended
	Dec. 31, 2017
Leases [Line Items]
Tenant Leases	13. TENANT LEASES  The Properties are leased to tenants under operating leases with various expiration dates through 2035 . Substantially all of the commercial leases provide for annual base rents plus recoveries and escalation charges based upon the tenant’s proportionate share of and/or increases in real estate taxes and certain operating costs, as defined, and the pass ‑through of charges for electrical usage.  Future minimum rentals to be received under non-cancelable commercial operating leases at December 31, 2017 are as follows (dollars in thousands) :     Year Amount  2018 $ 362,261  2019 328,399  2020 296,227  2021 265,393  2022 237,020  2023 and thereafter 951,264   Total $ 2,440,564      Multi-family rental property residential leases are excluded from the above table as they generally expire with in one year.
Mack-Cali Realty LP [Member]
Leases [Line Items]
Tenant Leases	13. TENANT LEASES  The Properties are leased to tenants under operating leases with various expiration dates through 2035 . Substantially all of the commercial leases provide for annual base rents plus recoveries and escalation charges based upon the tenant’s proportionate share of and/or increases in real estate taxes and certain operating costs, as defined, and the pass ‑through of charges for electrical usage.  Future minimum rentals to be received under non-cancelable commercial operating leases at December 31, 2017 are as follows (dollars in thousands) :     Year Amount  2018 $ 362,261  2019 328,399  2020 296,227  2021 265,393  2022 237,020  2023 and thereafter 951,264   Total $ 2,440,564      Multi-family rental property residential leases are excluded from the above table as they generally expire with in one year.

Redeemable Noncontrolling Inter

Redeemable Noncontrolling Interests	12 Months Ended
	Dec. 31, 2017
Redeemable Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interests	14. REDEEMABLE NONCONTROLLING INTERESTS  The Company evaluates the terms of the partnership units issued in accordance with the FASB’s Distinguishing Liabilities from Equity guidance. Units which embody an unconditional obligation requiring the Company to redeem the units for cash after a specified or determinable date (or dates) or upon the occurrence of an event that is not solely within the control of the issuer are determined to be contingently redeemable under this guidance and are included as Redeemable noncontrolling interests and classified within the mezzanine section between Total liabilities and Stockholders’ equity on the Company’s Consolidated Balance Sheets. Convertible units for which the Company has the option to settle redemption amounts in cash or Common Stock are included in the caption Noncontrolling interests in subsidiaries within the equity section on the Company’s Consolidated Balance Sheet.  Rockpoint Transaction On February 27, 2017, the Company, Roseland Residential Trust (“RRT”), the Company’s wholly-owned subsidiary through which the Company conducts its multi-family residential real estate operations, Roseland Residential, L.P. (“RRLP”), the operating partnership through which RRT conducts all of its operations, and certain other affiliates of the Company entered into an equity investment agreement (the “Investment Agreement”) with Rockpoint Group, L.L.C. and certain of its affiliates (collectively, “Rockpoint”). The Investment Agreement provides for multiple equity investments by Rockpoint in RRLP from time to time for up to an aggregate of $300 million of equity units of limited partnership interests of RRLP (the “Rockpoint Units”). The initial closing under the Investment Agreement occurred on March 10, 2017 for $150 million of Rockpoint Units and the parties agreed that the Company's contributed equity value, (“RRT Contributed Equity Value”), was $1.23 billion at closing. Additional closings of Rockpoint Units to be issued and sold to Rockpoint pursuant to the Investment Agreement may occur from time to time in increments of not less than $10 million per closing, with the balance of the full $300 million by March 1, 2019.  The Company has a participation right, where prior to March 1, 2022 and following either the full investment of $300 million by Rockpoint or in certain other limited circumstances, the Company may contribute up to $200 million to obtain equity units on substantially the same terms and conditions as the Rockpoint Units to be issued and sold to Rockpoint.  Under the terms of the transaction, the cash flow from operations of RRLP will be distributable to RRT and Rockpoint as follows:  first, to provide a 6% annual return to Rockpoint (and to the Company after it contributes to RRT to obtain equity units, as described above) on its invested capital (“Preferred Base Return”); second, to provide a 6% annual return on the equity value of the properties contributed by it to the partnership (“RRT Base Return”) with 95% of the RRT Base Return to RRT and 5% of the RRT Base Return to Rockpoint; and third, pro rata between Rockpoint (and the Company upon its contribution to obtain equity units) and RRT based on total respective invested capital by Rockpoint and RRT Initial Capital Contribution.  Based on Rockpoint’s $150 million invested capital and RRT’s Initial Capital Contribution, at December 31, 2017 this pro rata distribution would be approximately 10.9% to Rockpoint and 89.1% to RRT.  RRLP’s cash flow from capital events will generally be distributable to RRT and Rockpoint as follows:  first, to Rockpoint (and the Company after it contributes to RRT to obtain equity units) to the extent there is any unpaid, accrued Preferred Base Return; second, as a return of capital to Rockpoint (and the Company after it contributes to RRT to obtain equity units); third, to RRT to the extent there is any unpaid, accrued RRT Base Return (with Rockpoint entitled to 5% of the amounts distributable to RRT); fourth, as a return of capital to RRT based on the equity value of the properties contributed by it to the partnership (with Rockpoint entitled to 5% of the amounts distributable to RRT); fifth, pro rata between Rockpoint (and the Company after it contributes to RRT to obtain equity units) and RRT based on total respective invested capital and contributed equity value until Rockpoint has achieved an 11% internal rate of return; and sixth, to Rockpoint (and to the Company after it contributes to RRT to obtain equity units) based on 50% of its pro rata share described in “fifth” above and the balance to RRT.  In general, RRLP may not sell its properties in a taxable transaction, although it may engage in tax-deferred like-kind exchanges of properties or it may proceed in another manner designed to avoid the recognition of gains for tax purposes.  Beginning March 1, 2022, except in certain limited circumstances as defined in the agreement, either RRT or Rockpoint may cause RRT to redeem (a “Put/Call Event”) all, but not less than all, of Rockpoint’s interest in the Rockpoint Units based on a net asset value of RRLP to be determined by a third party valuation and generally based on the capital event waterfall described above. On a Put/Call Event, other than the sale of RRLP, Rockpoint can either demand payment in cash or may elect to convert all, but not less than all, of its investment to common equity in RRLP. As such, the Rockpoint Units contain a substantive redemption feature that is outside of the Company’s control and accordingly, pursuant to ASC 480-1--S99-3A, the Rockpoint Units are classified in mezzanine equity measured based on the estimated future redemption value as of December 31, 2017. The estimated future redemption value of Rockpoint Units is approximately $223 million as of December 31, 2017.  Preferred Units On February 3, 2017, the Operating Partnership issued 42,800 shares of a new class of 3.5 percent Series A Preferred Limited Partnership Units of the Operating Partnership (the “Series A Units”). The Series A Units were issued to the Company’s partners in the Plaza VIII & IX Associates L.L.C. joint venture that owns a development site adjacent to the Company’s Harborside property in Jersey City, New Jersey as non-cash consideration for their approximate 37.5 percent interest in the joint venture.  Each Series A Unit has a stated value of $1,000 , pays dividends quarterly at an annual rate of 3.5 percent (subject to increase under certain circumstances), is convertible into 28.15 common units of limited partnership interests of the Operating Partnership beginning generally five years from the date of issuance, or an aggregate of up to 1,204,820 common units. The conversion rate was based on a value of $35.52 per common unit. The Series A Units have a liquidation and dividend preference senior to the common units and include customary anti-dilution protections for stock splits and similar events. The Series A Units are redeemable for cash at their stated value beginning five years from the date of issuance at the option of the holder.  On February 28, 2017, the Operating Partnership authorized the issuance of 9,213 shares of a new class of 3.5 percent Series A-1 Preferred Limited Partnership Units of the Operating Partnership (the “Series A-1 Units”). 9,122 Series A-1 Units were issued on February 28, 2017 and an additional 91 Series A-1 Units were issued in April 2017 pursuant to acquiring additional interests in a joint venture that owns Monaco Towers in Jersey City, New Jersey. The Series A-1 Units were issued as non-cash consideration for the partner’s approximate 13.8 percent ownership interest in the joint venture.  Each Series A-1 Unit has a stated value of $1,000 (the “Stated Value”), pays dividends quarterly at an annual rate equal to the greater of (x) 3.5 percent, or (y) the then-effective annual dividend yield on the General Partner’s common stock, and is convertible into 27.936 common units of limited partnership interests of the Operating Partnership beginning generally five years from the date of issuance, or an aggregate of up to 257,375 Common Units. The conversion rate was based on a value of $35.80 per common unit. The Series A-1 Units have a liquidation and dividend preference senior to the Common Units and include customary anti-dilution protections for stock splits and similar events. The Series A-1 Units are redeemable for cash at their stated value beginning five years from the date of issuance at the option of the holder. The Series A-1 Units are pari passu with the 42,800 3.5% Series A Units issued on February 3, 2017.  The following table sets forth the changes in Redeemable noncontrolling interests for the year ended December 31, 2017 (dollars in thousands) :      Series A and Total  A-1 Preferred Rockpoint Redeemable  Units Interests Noncontrolling  In MCRLP in RRT Interests  Balance January 1, 2017 $ - $ - $ -  Redeemable Noncontrolling Interests Issued 52,013 150,000 202,013  Issuance Costs (464) (10,563) (11,027)  Net 51,549 139,437 190,986  Income Attributed to Noncontrolling Interests 1,631 7,209 8,840  Distributions (1,631) (7,209) (8,840)  Redemption Value Adjustment 775 20,447 21,222  Redeemable noncontrolling interests as of December 31, 2017 $ 52,324 $ 159,884 $ 212,208 
Mack-Cali Realty LP [Member]
Redeemable Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interests	14. REDEEMABLE NONCONTROLLING INTERESTS  The Company evaluates the terms of the partnership units issued in accordance with the FASB’s Distinguishing Liabilities from Equity guidance. Units which embody an unconditional obligation requiring the Company to redeem the units for cash after a specified or determinable date (or dates) or upon the occurrence of an event that is not solely within the control of the issuer are determined to be contingently redeemable under this guidance and are included as Redeemable noncontrolling interests and classified within the mezzanine section between Total liabilities and Stockholders’ equity on the Company’s Consolidated Balance Sheets. Convertible units for which the Company has the option to settle redemption amounts in cash or Common Stock are included in the caption Noncontrolling interests in subsidiaries within the equity section on the Company’s Consolidated Balance Sheet.  Rockpoint Transaction On February 27, 2017, the Company, Roseland Residential Trust (“RRT”), the Company’s wholly-owned subsidiary through which the Company conducts its multi-family residential real estate operations, Roseland Residential, L.P. (“RRLP”), the operating partnership through which RRT conducts all of its operations, and certain other affiliates of the Company entered into an equity investment agreement (the “Investment Agreement”) with Rockpoint Group, L.L.C. and certain of its affiliates (collectively, “Rockpoint”). The Investment Agreement provides for multiple equity investments by Rockpoint in RRLP from time to time for up to an aggregate of $300 million of equity units of limited partnership interests of RRLP (the “Rockpoint Units”). The initial closing under the Investment Agreement occurred on March 10, 2017 for $150 million of Rockpoint Units and the parties agreed that the Company's contributed equity value, (“RRT Contributed Equity Value”), was $1.23 billion at closing. Additional closings of Rockpoint Units to be issued and sold to Rockpoint pursuant to the Investment Agreement may occur from time to time in increments of not less than $10 million per closing, with the balance of the full $300 million by March 1, 2019.  The Company has a participation right, where prior to March 1, 2022 and following either the full investment of $300 million by Rockpoint or in certain other limited circumstances, the Company may contribute up to $200 million to obtain equity units on substantially the same terms and conditions as the Rockpoint Units to be issued and sold to Rockpoint.  Under the terms of the transaction, the cash flow from operations of RRLP will be distributable to RRT and Rockpoint as follows:  first, to provide a 6% annual return to Rockpoint (and to the Company after it contributes to RRT to obtain equity units, as described above) on its invested capital (“Preferred Base Return”); second, to provide a 6% annual return on the equity value of the properties contributed by it to the partnership (“RRT Base Return”) with 95% of the RRT Base Return to RRT and 5% of the RRT Base Return to Rockpoint; and third, pro rata between Rockpoint (and the Company upon its contribution to obtain equity units) and RRT based on total respective invested capital by Rockpoint and RRT Initial Capital Contribution.  Based on Rockpoint’s $150 million invested capital and RRT’s Initial Capital Contribution, at December 31, 2017 this pro rata distribution would be approximately 10.9% to Rockpoint and 89.1% to RRT.  RRLP’s cash flow from capital events will generally be distributable to RRT and Rockpoint as follows:  first, to Rockpoint (and the Company after it contributes to RRT to obtain equity units) to the extent there is any unpaid, accrued Preferred Base Return; second, as a return of capital to Rockpoint (and the Company after it contributes to RRT to obtain equity units); third, to RRT to the extent there is any unpaid, accrued RRT Base Return (with Rockpoint entitled to 5% of the amounts distributable to RRT); fourth, as a return of capital to RRT based on the equity value of the properties contributed by it to the partnership (with Rockpoint entitled to 5% of the amounts distributable to RRT); fifth, pro rata between Rockpoint (and the Company after it contributes to RRT to obtain equity units) and RRT based on total respective invested capital and contributed equity value until Rockpoint has achieved an 11% internal rate of return; and sixth, to Rockpoint (and to the Company after it contributes to RRT to obtain equity units) based on 50% of its pro rata share described in “fifth” above and the balance to RRT.  In general, RRLP may not sell its properties in a taxable transaction, although it may engage in tax-deferred like-kind exchanges of properties or it may proceed in another manner designed to avoid the recognition of gains for tax purposes.  Beginning March 1, 2022, except in certain limited circumstances as defined in the agreement, either RRT or Rockpoint may cause RRT to redeem (a “Put/Call Event”) all, but not less than all, of Rockpoint’s interest in the Rockpoint Units based on a net asset value of RRLP to be determined by a third party valuation and generally based on the capital event waterfall described above. On a Put/Call Event, other than the sale of RRLP, Rockpoint can either demand payment in cash or may elect to convert all, but not less than all, of its investment to common equity in RRLP. As such, the Rockpoint Units contain a substantive redemption feature that is outside of the Company’s control and accordingly, pursuant to ASC 480-1--S99-3A, the Rockpoint Units are classified in mezzanine equity measured based on the estimated future redemption value as of December 31, 2017. The estimated future redemption value of Rockpoint Units is approximately $223 million as of December 31, 2017.  Preferred Units On February 3, 2017, the Operating Partnership issued 42,800 shares of a new class of 3.5 percent Series A Preferred Limited Partnership Units of the Operating Partnership (the “Series A Units”). The Series A Units were issued to the Company’s partners in the Plaza VIII & IX Associates L.L.C. joint venture that owns a development site adjacent to the Company’s Harborside property in Jersey City, New Jersey as non-cash consideration for their approximate 37.5 percent interest in the joint venture.  Each Series A Unit has a stated value of $1,000 , pays dividends quarterly at an annual rate of 3.5 percent (subject to increase under certain circumstances), is convertible into 28.15 common units of limited partnership interests of the Operating Partnership beginning generally five years from the date of issuance, or an aggregate of up to 1,204,820 common units. The conversion rate was based on a value of $35.52 per common unit. The Series A Units have a liquidation and dividend preference senior to the common units and include customary anti-dilution protections for stock splits and similar events. The Series A Units are redeemable for cash at their stated value beginning five years from the date of issuance at the option of the holder.  On February 28, 2017, the Operating Partnership authorized the issuance of 9,213 shares of a new class of 3.5 percent Series A-1 Preferred Limited Partnership Units of the Operating Partnership (the “Series A-1 Units”). 9,122 Series A-1 Units were issued on February 28, 2017 and an additional 91 Series A-1 Units were issued in April 2017 pursuant to acquiring additional interests in a joint venture that owns Monaco Towers in Jersey City, New Jersey. The Series A-1 Units were issued as non-cash consideration for the partner’s approximate 13.8 percent ownership interest in the joint venture.  Each Series A-1 Unit has a stated value of $1,000 (the “Stated Value”), pays dividends quarterly at an annual rate equal to the greater of (x) 3.5 percent, or (y) the then-effective annual dividend yield on the General Partner’s common stock, and is convertible into 27.936 common units of limited partnership interests of the Operating Partnership beginning generally five years from the date of issuance, or an aggregate of up to 257,375 Common Units. The conversion rate was based on a value of $35.80 per common unit. The Series A-1 Units have a liquidation and dividend preference senior to the Common Units and include customary anti-dilution protections for stock splits and similar events. The Series A-1 Units are redeemable for cash at their stated value beginning five years from the date of issuance at the option of the holder. The Series A-1 Units are pari passu with the 42,800 3.5% Series A Units issued on February 3, 2017.  The following table sets forth the changes in Redeemable noncontrolling interests for the year ended December 31, 2017 (dollars in thousands) :      Series A and Total  A-1 Preferred Rockpoint Redeemable  Units Interests Noncontrolling  In MCRLP in RRT Interests  Balance January 1, 2017 $ - $ - $ -  Redeemable Noncontrolling Interests Issued 52,013 150,000 202,013  Issuance Costs (464) (10,563) (11,027)  Net 51,549 139,437 190,986  Income Attributed to Noncontrolling Interests 1,631 7,209 8,840  Distributions (1,631) (7,209) (8,840)  Redemption Value Adjustment 775 20,447 21,222  Redeemable noncontrolling interests as of December 31, 2017 $ 52,324 $ 159,884 $ 212,208 

Mack-Cali Realty Corporation St

Mack-Cali Realty Corporation Stockholders' Equity And Mack-Cali Realty, L.P.'s Partners' Capital	12 Months Ended
	Dec. 31, 2017
Stockolders Equity [Line Items]
Mack-Cali Realty Corporation Stockholders' Equity And Mack-Cali Realty, L.P.'s Partners' Capital	1 5 . MACK-CALI REALTY CORPORATION STOCKHOLDERS’ EQUITY AND MACK-CALI REALTY, L.P.’S PARTNERS’ CAPITAL  To maintain its qualification as a REIT, not more than 50 percent in value of the outstanding shares of the General Partner may be owned, directly or indirectly, by five or fewer individuals at any time during the last half of any taxable year of the General Partner, other than its initial taxable year (defined to include certain entities), applying certain constructive ownership rules. To help ensure that the General Partner will not fail this test, the General Partner’s Charter provides, among other things, certain restrictions on the transfer of common stock to prevent further concentration of stock ownership. Moreover, to evidence compliance with these requirements, the General Partner must maintain records that disclose the actual ownership of its outstanding common stock and demands written statements each year from the holders of record of designated percentages of its common stock requesting the disclosure of the beneficial owners of such common stock.  Partners’ Capital in the accompanying consolidated financial statements relates to (a) General Partners’ capital consisting of common units in the Operating Partnership held by the General Partner, and (b) Limited Partners’ capital consisting of common units and LTIP units held by the limited partners. See Note 16: Noncontrolling Interests in Subsidiaries.  Any transactions resulting in the issuance of additional common and preferred stock of the General Partner result in a corresponding issuance by the Operating Partnership of an equivalent amount of common and preferred units to the General Partner.  SHARE /UNIT REPURCHASE PROGRAM In September 2012 , the Board of Directors of the General Partner renewed and authorized an increase to the General Partner ’s repurchase program (“Repurchase Program”). The General Partner has authorization to repurchase up to $ 150 million of its outstanding common stock under the renewed Repurchase Program, which it may repurchase from time to time in open market transactions at prevailing prices or through privately negotiated transactions. As of December 31, 2017, t he General Partner has re purchased and retired 394,625 shares of its outstanding common stock for an aggregate cost of approximately $ 11 million (all of which occurred in the year ended December 31, 201 2 ), with a remaining authorization under the Repurchase Program of $ 139 million. Concurrent with these repurchases, the General Partner sold to the Operating Partnership common units for approximately $11 million. DIVIDEND REINVESTMENT AND STOCK PURCHASE PLAN The General Partner has a Dividend Reinvestment and Stock Purchase Plan (the “DRIP”) which commenced in March 1999 under which approximately 5.5 million shares of the General Partner’s common stock have been reserved for future issuance. The DRIP provides for automatic reinvestment of all or a portion of a participant’s dividends from the General Partner’s shares of common stock. The DRIP also permits participants to make optional cash investments up to $ 5,000 a month without restriction and, if the Company waives this limit, for additional amounts subject to certain restrictions and other conditions set forth in the DRIP prospectus filed as part of the Company’s effective registration statement on Form S-3 filed with the SEC for the approximately 5.5 million shares of the General Partner’s common stock reserved for issuance under the DRIP.  STOCK OPTION PLANS In May 2013, the General Partner established the 2013 Incentive Stock Plan (the “2013 Plan”) under which a total of 4,600,000 shares have been reserved for issuance.  On June 5, 2015, in connection with employment agreements entered into with each of Messrs. Rudin and DeMarco (together the “Executive Employment Agreements”), the Company granted options to purchase a total of 800,000 shares of the General Partner’s common stock, exercisable for a period of ten years with an exercise price equal to the closing price of the General Partner’s common stock on the grant date of $17.31 per share, with 400,000 of such options vesting in three equal annual installments commencing on the first anniversary of the grant date (“Time Vesting Options”), and 400,000 of such options vesting if the General Partner’s common stock trades at or above $25.00 per share for 30 consecutive trading days while the executive is employed (“Price Vesting Options”), or on or before June 30, 2019, subject to certain conditions. The Price Vesting Options vested on July 5, 2016 on account of the price vesting condition being achieved.  Information regarding the Company’s stock option plans is summarized below:    Weighted Aggregate  Average Intrinsic  Shares Exercise Value  Under Options Price $(000’s)  Outstanding at January 1, 2015 10,000 $ 33.36 $ -  Granted 800,000 17.31  Lapsed or Cancelled (5,000) 45.47  Outstanding at December 31, 2015 ($17.31 – $21.25) 805,000 $ 17.33 4,843  Lapsed or Cancelled (5,000) 21.25  Outstanding at December 31, 2016 ($17.31) 800,000 $ 17.31 9,368  Granted, Lapsed or Cancelled - -  Outstanding at December 31, 2017 ($17.31) 800,000 $ 17.31 $ 3,400  Options exercisable at December 31, 2017 666,666  Available for grant at December 31, 2017 2,069,064  The weighted average fair value of options granted during the year ended December 31, 2015 was $3.06 per option. The fair value of each option grant is estimated on the date of grant using the Black-Scholes model for Time Vesting Options granted and the Monte Carlo method for Price Vesting Options granted, during the year ended December 31, 2015 . The following weighted average assumptions are included in the Company’s fair value calculations of stock options granted during the year ended December 31, 2015:     2015  Time Vesting Price Vesting  Options Options  Expected life (in years) 6.0 5.8  Risk-free interest rate 2.04 % 1.96 %  Volatility 29.0 % 29.0 %  Dividend yield 3.5 % 3.5 %  There were no stock options exercised under a ny stock option plans for the year s ended December 31, 2017 , 2016 and 2015 . The Comp any has a policy of issuing new shares to satisfy stock option exercises.  As of December 31, 2017 and 2016 , the stock options outstanding had a weighted average remaining contractual life of approximately 7.4 years and 8.4 years, respectively.  The Company recognized stock opt ions expense of $ 464,000 , $ 1,407,000 and $ 432,000 for the years ended December 31, 2017 , 2016 and 2015 , respectively.  RESTRICTED STOCK AWARDS The Company has issued stock awards (“Restricted Stock Awards”) to officers, certain other employees, and non - employee members of the Board of Directors of the General Partner , which allow the holders to each receive a certain amount of shares of the General Partner ’s common stock generally over a one to seven -year vesting period, of which 95,801 unvested shares were legally outstanding at December 31, 2017 . Vesting of the Restricted Stock Awards issued to executive officers and certain other employees is based on time and service.  On June 5, 2015, in connection with the Executive Employment Agreements, the Company granted a total of 37,550.54 Restricted Stock Awards, which were valued in accordance with ASC 718 – Stock Compensation, at their fair value. These awards vest equally over a three -year period on each annual anniversary date of the grant date.  All currently outstanding and unvested Restricted Stock Awards provided to the officers, certain other employees, and members of the Board of Directors of the General Partner were issued under the 2013 Plan.  Information regarding the Restricted Stock Awards grant activity is summarized below:    Weighted-Average  Grant – Date  Shares Fair Value  Outstanding at January 1, 2015 346,946 $ 21.09  Granted (a) 41,337 17.51  Vested (250,132) 21.44  Forfeited (1,931) 20.31  Outstanding at December 31, 2015 136,220 $ 19.36  Granted 74,622 23.79  Vested (61,654) 18.94  Forfeited (3,910) 21.58  Outstanding at December 31, 2016 145,278 $ 21.76  Granted 59,985 27.00  Vested (95,009) 20.73  Forfeited (1,936) 25.83  Outstanding at December 31, 2017 108,318 $ 25.49  ( a ) Included in the 41,337 Restricted Stock Awards granted in 2015 were 37,551 awards granted to the Company’s two executive officers, Mitchell E. Rudin and Michael J. DeMarco. As of December 31, 2017 , the Company had $0.9 million of total unrecognized compensation cost related to unvested Restricted Stock Awards granted under the Company’s stock compensation plans. That cost is expected to be recognized over a weighted average period of 1.2 years.  PERFORMANCE SHARE UNITS On June 5, 2015, in connection with the Executive Employment Agreements, the Company granted a total of 112,651.64 performance share units (“PSUs”) which will vest from 0 to 150 percent of the number of PSUs granted based on the Company’s total shareholder return relative to a peer group of equity office REITs over a three -year performance period starting from the grant date, each PSU evidencing the right to receive a share of the General Partner’s common stock upon vesting. The PSUs are also entitled to the payment of dividend equivalents in respect of vested PSUs in the form of additional PSUs. The PSUs were valued in accordance with ASC 718, Compensation - Stock Compensation, at their fair value on the grant date, utilizing a Monte-Carlo simulation to estimate the probability of the vesting conditions being satisfied.  The Company has reserved shares of common stock under the 2013 Plan for issuance upon vesting of the PSUs in accordance with their terms and conditions.  As of December 31, 2017 , the Company had $0.2 million of total unrecognized compensation cost related to unvested PSUs granted under the Company’s stock compensation plans. That cost is expected to be recognized over a weighted average period of 0.4 years.  LONG-TERM INCENTIVE PLAN AWARDS On March 8, 2016, the Company granted Long-Term Incentive Plan (“LTIP”) awards to senior management of the Company, including the General Partner’s executive officers (the “2016 LTIP Awards”). All of the 2016 LTIP Awards were in the form of units in the Operating Partnership (“LTIP Units”) and constitute awards under the 2013 Plan. For Messrs. Rudin, DeMarco and Tycher, approximately 25 percent of the target 2016 LTIP Award was in the form of a time-based award that will vest after three years on March 8, 2019 (the “2016 TBV LTIP Units”), and the remaining approximately 75 percent of the target 2016 LTIP Award was in the form of a performance-based award under a new Outperformance Plan (the “2016 OPP”) adopted by the General Partner’s Board of Directors consisting of a multi-year, performance-based equity compensation plan and related forms of award agreement (the “2016 PBV LTIP Units”). For all other executive officers, approximately 40 percent of the target 2016 LTIP Award was in the form of 2016 TBV LTIP Units and the remaining approximately 60 percent of the target 2016 LTIP Award was in the form of 2016 PBV LTIP Units.  The 2016 OPP is designed to align the interests of senior management to relative and absolute performance of the Company over a three-year performance period from March 8, 2016 through March 7, 2019. Participants in the 2016 OPP will only earn the full awards if, over the three -year performance period, the Company achieves a 50 percent absolute total stockholder return (“TSR”) and if the Company is in the 75th percentile of performance versus the NAREIT Office Index.  On April 4, 2017, the Company granted LTIP awards to senior management of the Company, including the General Partner’s executive officers (the “2017 LTIP Awards”). All of the 2017 LTIP Awards were in the form of LTIP Units and constitute awards under the 2013 Plan. For Messrs. DeMarco, Tycher and Rudin, approximately twenty-five percent ( 25% ) of the 2017 LTIP Award was in the form of a time-based award that will vest after three years on April 4, 2020 (the “2017 TBV LTIP Units”), and the remaining approximately seventy-five percent ( 75% ) of the 2017 LTIP Award was in the form of a performance-based award under the Company’s Outperformance Plan (the “2017 OPP”) adopted by the General Partner’s Board of Directors, consisting of a multi-year, performance-based equity compensation plan and related forms of award agreement (the “2017 PBV LTIP Units”). For all other executive officers, approximately forty percent ( 40% ) of the 2017 LTIP Award was in the form of 2017 TBV LTIP Units and the remaining approximately sixty percent ( 60% ) of the 2017 LTIP Award was in the form of 2017 PBV LTIP Units.  The 2017 OPP is designed to align the interests of senior management to relative and absolute performance of the Company over a three-year performance period from April 4, 2017 through April 3, 2020. Participants in the 2017 OPP will only earn the full awards if, over the three -year performance period, the Company achieves a thirty-six percent ( 36% ) absolute TSR and if the Company is in the 75th percentile of performance as compared to the NAREIT office index.  LTIP Units will remain subject to forfeiture depending on the extent that the 2016 LTIP Awards and 2017 LTIP Awards vest. The number of LTIP Units to be issued initially to recipients of the 2016 PBV LTIP Awards and 2017 PBV LTIP Awards is the maximum number of LTIP Units that may be earned under the awards. The number of LTIP Units that actually vest for each award recipient will be determined at the end of the performance measurement period. TSR for the Company and for the Index over the three-year measurement period and other circumstances will determine how many LTIP Units vest for each recipient; if they are fewer than the number issued initially, the balance will be forfeited as of the performance measurement date.  Prior to vesting, recipients of LTIP Units will be entitled to receive per unit distributions equal to one-tenth ( 10 percent) of the regular quarterly distributions payable on a common unit of limited partnership interest in the Operating Partnership (a “common unit”), but will not be entitled to receive any special distributions. Distributions with respect to the other nine-tenths ( 90 percent) of regular quarterly distributions payable on a common unit will accrue but shall only become payable upon vesting of the LTIP Unit. After vesting of the 2016 TBV LTIP Units and 2017 TBV LTIP Units or the end of the measurement period for the 2016 PBV LTIP Units and 2017 PBV LTIP Units, the number of LTIP Units, both vested and unvested, will be entitled to receive distributions in an amount per unit equal to distributions, both regular and special, payable on a common unit.  As of December 31, 2017, the Company granted a total of 496,781 2016 PBV LTIP Units, 155,773 2016 TBV LTIP Units, 481,436 2017 PBV LTIP Units and 96,887 2017 TBV LTIP Units. The LTIP Units were valued in accordance with ASC 718 – Stock Compensation, at their fair value. The Company has reserved shares of common stock under the 2013 Plan for issuance upon vesting and conversion of the LTIP Units in accordance with their terms and conditions.  As of December 31, 2017 , the Company had $11.1 million of total unrecognized compensation cost related to unvested LTIP awards granted under the Company’s stock compensation plans. That cost is expected to be recognized over a weighted average period of 2.5 years.  DEFERRED STOCK COMPENSATION PLAN FOR DIRECTORS The Amended and Restated Deferred Compensation Plan for Directors, which commenced January 1, 1999, allows non ‑employee directors of the Company to elect to defer up to 100 percent of their annual retainer fee into deferred stock units. The deferred stock units are convertible into an equal number of shares of common stock upon the directors’ termination of service from the Board of Directors or a change in control of the Company, as defined in the plan. Deferred stock units are credited to each director quarterly using the closing price of the Company’s common stock on the applicable dividend record date for the respective quarter. Each participating director’s account is also credited for an equivalent amount of deferred stock units based on the dividend rate for each quarter.  During the year s ended December 31, 2017 , 2016 and 2015 , 19,728 , 14,274 and 19,702 deferred stock units were earned, respectively. As of December 31, 2017 and 2016 , there were 210,738 and 193,711 deferred stock units outstanding, respectively.  EARNINGS PER SHARE /UNIT Basic EPS or EPU excludes dilution and is computed by dividing net income available to common shareholders or unitholders by the weighted average number of shares or units outstanding for the period. Diluted EPS or EPU reflects the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock.  The following information presents the Company’s results for the years ended December 31, 2017 , 2016 and 2015 in accordance with ASC 260, Earning s Per Share: (dollars in thousands, except per share amounts)  Mack-Cali Realty Corporation:   Year Ended December 31,  Computation of Basic EPS 2017 2016 2015  Net income (loss) $ 33,718 $ 130,294 $ (142,052)  Add: Noncontrolling interest in consolidated joint ventures 1,018 651 1,044  Add (deduct): Noncontrolling interest in Operating Partnership (2,711) (13,721) 15,256  Deduct: Redeemable noncontrolling interest (8,840) - -  Deduct: Redemption value adjustment of redeemable noncontrolling  interests attributable to common shareholders (17,951) - -  Net income (loss) available to common shareholders for basic earnings per share $ 5,234 $ 117,224 $ (125,752)   Weighted average common shares 90,005 89,746 89,291   Basic EPS :  Net income (loss) available to common shareholders $ 0.06 $ 1.31 $ (1.41)         Year Ended December 31,  Computation of Diluted EPS 2017 2016 2015  Net income (loss) available to common shareholders for basic earnings per share $ 5,234 $ 117,224 $ (125,752)  Add (deduct): Noncontrolling interest in Operating Partnership 2,711 13,721 (15,256)  Deduct: Redemption value adjustment of redeemable noncontrolling  interests attributable to the Operating Partnership unitholders (2,074) - -  Net income (loss) for diluted earnings per share $ 5,871 $ 130,945 $ (141,008)   Weighted average common shares 100,703 100,498 100,222   Diluted EPS :  Net income (loss) available to common shareholders $ 0.06 $ 1.30 $ (1.41)   The following schedule reconciles the weighted average shares used in the basic EPS calculation to the shares used in the diluted EPS calculation: (in thousands)   Year Ended December 31,  2017 2016 2015  Basic EPS shares 90,005 89,746 89,291  Add: Operating Partnership – common units 10,405 10,499 10,931  Restricted Stock Awards 40 43 -  Stock Options 253 210 -  Diluted EPS Shares 100,703 100,498 100,222  Contingently issuable shares under the PSU Awards were excluded from the denominator in 2017 , 2016 and 2015 because the criteria had not been met for the periods. Contingently issuable shares under Restricted Stock Awards and all stock options were excluded from the denominator in 2015 as such securities were anti-dilutive during the period. Not included in the computations of diluted EPS were 405,000 stock options as such securities were ant i -dilutive during the year ended December 31, 2015 . Also not included in the computations of diluted EPS were all of the LTIP Units as such securities were anti-dilutive during all periods presented. Unvested restricted stock outstanding as of December 31, 2017 , 2016 and 2015 were 95,801 , 120,245 and 98,669 shares, respectively.  Dividends declared per common share for the years ended December 31, 2017 , 2016 and 2015 was $0.75 , $0.60 and $0.60 per share, respectively.  Mack-Cali Realty, L.P.:    Year Ended December 31,  Computation of Basic EPU 2017 2016 2015  Net income (loss) $ 33,718 $ 130,294 $ (142,052)  Add: Noncontrolling interest in consolidated joint ventures 1,018 651 1,044  Deduct: Redeemable noncontrolling interest (8,840) - -  Deduct: Redemption value adjustment of redeemable noncontrolling interests (20,025) - -  Net income (loss) available to common unitholders for basic earnings per unit $ 5,871 $ 130,945 $ (141,008)   Weighted average common units 100,410 100,245 100,222   Basic EPU :  Net income (loss) available to common unitholders for basic earnings per unit $ 0.06 $ 1.31 $ (1.41)    Year Ended December 31,  Computation of Diluted EPU 2017 2016 2015  Net income (loss) available to common unitholders for basic earnings per unit $ 5,871 $ 130,945 $ (141,008)   Weighted average common unit 100,703 100,498 100,222   Diluted EPU :  Net income (loss) available to common unitholders for basic earnings per unit $ 0.06 $ 1.30 $ (1.41)  The following schedule reconciles the weighted average units used in the basic EPU calculation to the units used in the diluted EPU calculation: (in thousands)    Year Ended December 31,  2017 2016 2015  Basic EPU units 100,410 100,245 100,222  Add: Restricted Stock Awards 40 43 -  Stock Options 253 210 -  Diluted EPU Units 100,703 100,498 100,222  Contingently issuable shares under the PSU Awards were excluded from the denominator in 2017 , 2016 and 2015 because the criteria had not been met for the periods. Contingently issuable shares under Restricted Stock Awards and all stock options were excluded from the denominator in 2015 as such securities were anti-dilutive during the period. Not included in the computations of diluted EPU were 405,000 stock options as such securities were anti-dilutive during the year ended December 31, 2015. Also not included in the computations of diluted EPU were all of the LTIP Units as such securities were anti-dilutive during all periods presented. Unvested restricted stock outstanding as of December 31, 2017 , 2016 and 2015 were 95,801 , 120,245 and 98,669 shares, respectively.  Distributions declared per common unit for the years ended December 31, 2017 , 2016 and 2015 was $ 0.75 , $0.60 and $0.60 per unit, respectively.
Mack-Cali Realty LP [Member]
Stockolders Equity [Line Items]
Mack-Cali Realty Corporation Stockholders' Equity And Mack-Cali Realty, L.P.'s Partners' Capital	1 5 . MACK-CALI REALTY CORPORATION STOCKHOLDERS’ EQUITY AND MACK-CALI REALTY, L.P.’S PARTNERS’ CAPITAL  To maintain its qualification as a REIT, not more than 50 percent in value of the outstanding shares of the General Partner may be owned, directly or indirectly, by five or fewer individuals at any time during the last half of any taxable year of the General Partner, other than its initial taxable year (defined to include certain entities), applying certain constructive ownership rules. To help ensure that the General Partner will not fail this test, the General Partner’s Charter provides, among other things, certain restrictions on the transfer of common stock to prevent further concentration of stock ownership. Moreover, to evidence compliance with these requirements, the General Partner must maintain records that disclose the actual ownership of its outstanding common stock and demands written statements each year from the holders of record of designated percentages of its common stock requesting the disclosure of the beneficial owners of such common stock.  Partners’ Capital in the accompanying consolidated financial statements relates to (a) General Partners’ capital consisting of common units in the Operating Partnership held by the General Partner, and (b) Limited Partners’ capital consisting of common units and LTIP units held by the limited partners. See Note 16: Noncontrolling Interests in Subsidiaries.  Any transactions resulting in the issuance of additional common and preferred stock of the General Partner result in a corresponding issuance by the Operating Partnership of an equivalent amount of common and preferred units to the General Partner.  SHARE /UNIT REPURCHASE PROGRAM In September 2012 , the Board of Directors of the General Partner renewed and authorized an increase to the General Partner ’s repurchase program (“Repurchase Program”). The General Partner has authorization to repurchase up to $ 150 million of its outstanding common stock under the renewed Repurchase Program, which it may repurchase from time to time in open market transactions at prevailing prices or through privately negotiated transactions. As of December 31, 2017, t he General Partner has re purchased and retired 394,625 shares of its outstanding common stock for an aggregate cost of approximately $ 11 million (all of which occurred in the year ended December 31, 201 2 ), with a remaining authorization under the Repurchase Program of $ 139 million. Concurrent with these repurchases, the General Partner sold to the Operating Partnership common units for approximately $11 million. DIVIDEND REINVESTMENT AND STOCK PURCHASE PLAN The General Partner has a Dividend Reinvestment and Stock Purchase Plan (the “DRIP”) which commenced in March 1999 under which approximately 5.5 million shares of the General Partner’s common stock have been reserved for future issuance. The DRIP provides for automatic reinvestment of all or a portion of a participant’s dividends from the General Partner’s shares of common stock. The DRIP also permits participants to make optional cash investments up to $ 5,000 a month without restriction and, if the Company waives this limit, for additional amounts subject to certain restrictions and other conditions set forth in the DRIP prospectus filed as part of the Company’s effective registration statement on Form S-3 filed with the SEC for the approximately 5.5 million shares of the General Partner’s common stock reserved for issuance under the DRIP.  STOCK OPTION PLANS In May 2013, the General Partner established the 2013 Incentive Stock Plan (the “2013 Plan”) under which a total of 4,600,000 shares have been reserved for issuance.  On June 5, 2015, in connection with employment agreements entered into with each of Messrs. Rudin and DeMarco (together the “Executive Employment Agreements”), the Company granted options to purchase a total of 800,000 shares of the General Partner’s common stock, exercisable for a period of ten years with an exercise price equal to the closing price of the General Partner’s common stock on the grant date of $17.31 per share, with 400,000 of such options vesting in three equal annual installments commencing on the first anniversary of the grant date (“Time Vesting Options”), and 400,000 of such options vesting if the General Partner’s common stock trades at or above $25.00 per share for 30 consecutive trading days while the executive is employed (“Price Vesting Options”), or on or before June 30, 2019, subject to certain conditions. The Price Vesting Options vested on July 5, 2016 on account of the price vesting condition being achieved.  Information regarding the Company’s stock option plans is summarized below:    Weighted Aggregate  Average Intrinsic  Shares Exercise Value  Under Options Price $(000’s)  Outstanding at January 1, 2015 10,000 $ 33.36 $ -  Granted 800,000 17.31  Lapsed or Cancelled (5,000) 45.47  Outstanding at December 31, 2015 ($17.31 – $21.25) 805,000 $ 17.33 4,843  Lapsed or Cancelled (5,000) 21.25  Outstanding at December 31, 2016 ($17.31) 800,000 $ 17.31 9,368  Granted, Lapsed or Cancelled - -  Outstanding at December 31, 2017 ($17.31) 800,000 $ 17.31 $ 3,400  Options exercisable at December 31, 2017 666,666  Available for grant at December 31, 2017 2,069,064  The weighted average fair value of options granted during the year ended December 31, 2015 was $3.06 per option. The fair value of each option grant is estimated on the date of grant using the Black-Scholes model for Time Vesting Options granted and the Monte Carlo method for Price Vesting Options granted, during the year ended December 31, 2015 . The following weighted average assumptions are included in the Company’s fair value calculations of stock options granted during the year ended December 31, 2015:     2015  Time Vesting Price Vesting  Options Options  Expected life (in years) 6.0 5.8  Risk-free interest rate 2.04 % 1.96 %  Volatility 29.0 % 29.0 %  Dividend yield 3.5 % 3.5 %  There were no stock options exercised under a ny stock option plans for the year s ended December 31, 2017 , 2016 and 2015 . The Comp any has a policy of issuing new shares to satisfy stock option exercises.  As of December 31, 2017 and 2016 , the stock options outstanding had a weighted average remaining contractual life of approximately 7.4 years and 8.4 years, respectively.  The Company recognized stock opt ions expense of $ 464,000 , $ 1,407,000 and $ 432,000 for the years ended December 31, 2017 , 2016 and 2015 , respectively.  RESTRICTED STOCK AWARDS The Company has issued stock awards (“Restricted Stock Awards”) to officers, certain other employees, and non - employee members of the Board of Directors of the General Partner , which allow the holders to each receive a certain amount of shares of the General Partner ’s common stock generally over a one to seven -year vesting period, of which 95,801 unvested shares were legally outstanding at December 31, 2017 . Vesting of the Restricted Stock Awards issued to executive officers and certain other employees is based on time and service.  On June 5, 2015, in connection with the Executive Employment Agreements, the Company granted a total of 37,550.54 Restricted Stock Awards, which were valued in accordance with ASC 718 – Stock Compensation, at their fair value. These awards vest equally over a three -year period on each annual anniversary date of the grant date.  All currently outstanding and unvested Restricted Stock Awards provided to the officers, certain other employees, and members of the Board of Directors of the General Partner were issued under the 2013 Plan.  Information regarding the Restricted Stock Awards grant activity is summarized below:    Weighted-Average  Grant – Date  Shares Fair Value  Outstanding at January 1, 2015 346,946 $ 21.09  Granted (a) 41,337 17.51  Vested (250,132) 21.44  Forfeited (1,931) 20.31  Outstanding at December 31, 2015 136,220 $ 19.36  Granted 74,622 23.79  Vested (61,654) 18.94  Forfeited (3,910) 21.58  Outstanding at December 31, 2016 145,278 $ 21.76  Granted 59,985 27.00  Vested (95,009) 20.73  Forfeited (1,936) 25.83  Outstanding at December 31, 2017 108,318 $ 25.49  ( a ) Included in the 41,337 Restricted Stock Awards granted in 2015 were 37,551 awards granted to the Company’s two executive officers, Mitchell E. Rudin and Michael J. DeMarco. As of December 31, 2017 , the Company had $0.9 million of total unrecognized compensation cost related to unvested Restricted Stock Awards granted under the Company’s stock compensation plans. That cost is expected to be recognized over a weighted average period of 1.2 years.  PERFORMANCE SHARE UNITS On June 5, 2015, in connection with the Executive Employment Agreements, the Company granted a total of 112,651.64 performance share units (“PSUs”) which will vest from 0 to 150 percent of the number of PSUs granted based on the Company’s total shareholder return relative to a peer group of equity office REITs over a three -year performance period starting from the grant date, each PSU evidencing the right to receive a share of the General Partner’s common stock upon vesting. The PSUs are also entitled to the payment of dividend equivalents in respect of vested PSUs in the form of additional PSUs. The PSUs were valued in accordance with ASC 718, Compensation - Stock Compensation, at their fair value on the grant date, utilizing a Monte-Carlo simulation to estimate the probability of the vesting conditions being satisfied.  The Company has reserved shares of common stock under the 2013 Plan for issuance upon vesting of the PSUs in accordance with their terms and conditions.  As of December 31, 2017 , the Company had $0.2 million of total unrecognized compensation cost related to unvested PSUs granted under the Company’s stock compensation plans. That cost is expected to be recognized over a weighted average period of 0.4 years.  LONG-TERM INCENTIVE PLAN AWARDS On March 8, 2016, the Company granted Long-Term Incentive Plan (“LTIP”) awards to senior management of the Company, including the General Partner’s executive officers (the “2016 LTIP Awards”). All of the 2016 LTIP Awards were in the form of units in the Operating Partnership (“LTIP Units”) and constitute awards under the 2013 Plan. For Messrs. Rudin, DeMarco and Tycher, approximately 25 percent of the target 2016 LTIP Award was in the form of a time-based award that will vest after three years on March 8, 2019 (the “2016 TBV LTIP Units”), and the remaining approximately 75 percent of the target 2016 LTIP Award was in the form of a performance-based award under a new Outperformance Plan (the “2016 OPP”) adopted by the General Partner’s Board of Directors consisting of a multi-year, performance-based equity compensation plan and related forms of award agreement (the “2016 PBV LTIP Units”). For all other executive officers, approximately 40 percent of the target 2016 LTIP Award was in the form of 2016 TBV LTIP Units and the remaining approximately 60 percent of the target 2016 LTIP Award was in the form of 2016 PBV LTIP Units.  The 2016 OPP is designed to align the interests of senior management to relative and absolute performance of the Company over a three-year performance period from March 8, 2016 through March 7, 2019. Participants in the 2016 OPP will only earn the full awards if, over the three -year performance period, the Company achieves a 50 percent absolute total stockholder return (“TSR”) and if the Company is in the 75th percentile of performance versus the NAREIT Office Index.  On April 4, 2017, the Company granted LTIP awards to senior management of the Company, including the General Partner’s executive officers (the “2017 LTIP Awards”). All of the 2017 LTIP Awards were in the form of LTIP Units and constitute awards under the 2013 Plan. For Messrs. DeMarco, Tycher and Rudin, approximately twenty-five percent ( 25% ) of the 2017 LTIP Award was in the form of a time-based award that will vest after three years on April 4, 2020 (the “2017 TBV LTIP Units”), and the remaining approximately seventy-five percent ( 75% ) of the 2017 LTIP Award was in the form of a performance-based award under the Company’s Outperformance Plan (the “2017 OPP”) adopted by the General Partner’s Board of Directors, consisting of a multi-year, performance-based equity compensation plan and related forms of award agreement (the “2017 PBV LTIP Units”). For all other executive officers, approximately forty percent ( 40% ) of the 2017 LTIP Award was in the form of 2017 TBV LTIP Units and the remaining approximately sixty percent ( 60% ) of the 2017 LTIP Award was in the form of 2017 PBV LTIP Units.  The 2017 OPP is designed to align the interests of senior management to relative and absolute performance of the Company over a three-year performance period from April 4, 2017 through April 3, 2020. Participants in the 2017 OPP will only earn the full awards if, over the three -year performance period, the Company achieves a thirty-six percent ( 36% ) absolute TSR and if the Company is in the 75th percentile of performance as compared to the NAREIT office index.  LTIP Units will remain subject to forfeiture depending on the extent that the 2016 LTIP Awards and 2017 LTIP Awards vest. The number of LTIP Units to be issued initially to recipients of the 2016 PBV LTIP Awards and 2017 PBV LTIP Awards is the maximum number of LTIP Units that may be earned under the awards. The number of LTIP Units that actually vest for each award recipient will be determined at the end of the performance measurement period. TSR for the Company and for the Index over the three-year measurement period and other circumstances will determine how many LTIP Units vest for each recipient; if they are fewer than the number issued initially, the balance will be forfeited as of the performance measurement date.  Prior to vesting, recipients of LTIP Units will be entitled to receive per unit distributions equal to one-tenth ( 10 percent) of the regular quarterly distributions payable on a common unit of limited partnership interest in the Operating Partnership (a “common unit”), but will not be entitled to receive any special distributions. Distributions with respect to the other nine-tenths ( 90 percent) of regular quarterly distributions payable on a common unit will accrue but shall only become payable upon vesting of the LTIP Unit. After vesting of the 2016 TBV LTIP Units and 2017 TBV LTIP Units or the end of the measurement period for the 2016 PBV LTIP Units and 2017 PBV LTIP Units, the number of LTIP Units, both vested and unvested, will be entitled to receive distributions in an amount per unit equal to distributions, both regular and special, payable on a common unit.  As of December 31, 2017, the Company granted a total of 496,781 2016 PBV LTIP Units, 155,773 2016 TBV LTIP Units, 481,436 2017 PBV LTIP Units and 96,887 2017 TBV LTIP Units. The LTIP Units were valued in accordance with ASC 718 – Stock Compensation, at their fair value. The Company has reserved shares of common stock under the 2013 Plan for issuance upon vesting and conversion of the LTIP Units in accordance with their terms and conditions.  As of December 31, 2017 , the Company had $11.1 million of total unrecognized compensation cost related to unvested LTIP awards granted under the Company’s stock compensation plans. That cost is expected to be recognized over a weighted average period of 2.5 years.  DEFERRED STOCK COMPENSATION PLAN FOR DIRECTORS The Amended and Restated Deferred Compensation Plan for Directors, which commenced January 1, 1999, allows non ‑employee directors of the Company to elect to defer up to 100 percent of their annual retainer fee into deferred stock units. The deferred stock units are convertible into an equal number of shares of common stock upon the directors’ termination of service from the Board of Directors or a change in control of the Company, as defined in the plan. Deferred stock units are credited to each director quarterly using the closing price of the Company’s common stock on the applicable dividend record date for the respective quarter. Each participating director’s account is also credited for an equivalent amount of deferred stock units based on the dividend rate for each quarter.  During the year s ended December 31, 2017 , 2016 and 2015 , 19,728 , 14,274 and 19,702 deferred stock units were earned, respectively. As of December 31, 2017 and 2016 , there were 210,738 and 193,711 deferred stock units outstanding, respectively.  EARNINGS PER SHARE /UNIT Basic EPS or EPU excludes dilution and is computed by dividing net income available to common shareholders or unitholders by the weighted average number of shares or units outstanding for the period. Diluted EPS or EPU reflects the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock.  The following information presents the Company’s results for the years ended December 31, 2017 , 2016 and 2015 in accordance with ASC 260, Earning s Per Share: (dollars in thousands, except per share amounts)  Mack-Cali Realty Corporation:   Year Ended December 31,  Computation of Basic EPS 2017 2016 2015  Net income (loss) $ 33,718 $ 130,294 $ (142,052)  Add: Noncontrolling interest in consolidated joint ventures 1,018 651 1,044  Add (deduct): Noncontrolling interest in Operating Partnership (2,711) (13,721) 15,256  Deduct: Redeemable noncontrolling interest (8,840) - -  Deduct: Redemption value adjustment of redeemable noncontrolling  interests attributable to common shareholders (17,951) - -  Net income (loss) available to common shareholders for basic earnings per share $ 5,234 $ 117,224 $ (125,752)   Weighted average common shares 90,005 89,746 89,291   Basic EPS :  Net income (loss) available to common shareholders $ 0.06 $ 1.31 $ (1.41)         Year Ended December 31,  Computation of Diluted EPS 2017 2016 2015  Net income (loss) available to common shareholders for basic earnings per share $ 5,234 $ 117,224 $ (125,752)  Add (deduct): Noncontrolling interest in Operating Partnership 2,711 13,721 (15,256)  Deduct: Redemption value adjustment of redeemable noncontrolling  interests attributable to the Operating Partnership unitholders (2,074) - -  Net income (loss) for diluted earnings per share $ 5,871 $ 130,945 $ (141,008)   Weighted average common shares 100,703 100,498 100,222   Diluted EPS :  Net income (loss) available to common shareholders $ 0.06 $ 1.30 $ (1.41)   The following schedule reconciles the weighted average shares used in the basic EPS calculation to the shares used in the diluted EPS calculation: (in thousands)   Year Ended December 31,  2017 2016 2015  Basic EPS shares 90,005 89,746 89,291  Add: Operating Partnership – common units 10,405 10,499 10,931  Restricted Stock Awards 40 43 -  Stock Options 253 210 -  Diluted EPS Shares 100,703 100,498 100,222  Contingently issuable shares under the PSU Awards were excluded from the denominator in 2017 , 2016 and 2015 because the criteria had not been met for the periods. Contingently issuable shares under Restricted Stock Awards and all stock options were excluded from the denominator in 2015 as such securities were anti-dilutive during the period. Not included in the computations of diluted EPS were 405,000 stock options as such securities were ant i -dilutive during the year ended December 31, 2015 . Also not included in the computations of diluted EPS were all of the LTIP Units as such securities were anti-dilutive during all periods presented. Unvested restricted stock outstanding as of December 31, 2017 , 2016 and 2015 were 95,801 , 120,245 and 98,669 shares, respectively.  Dividends declared per common share for the years ended December 31, 2017 , 2016 and 2015 was $0.75 , $0.60 and $0.60 per share, respectively.  Mack-Cali Realty, L.P.:    Year Ended December 31,  Computation of Basic EPU 2017 2016 2015  Net income (loss) $ 33,718 $ 130,294 $ (142,052)  Add: Noncontrolling interest in consolidated joint ventures 1,018 651 1,044  Deduct: Redeemable noncontrolling interest (8,840) - -  Deduct: Redemption value adjustment of redeemable noncontrolling interests (20,025) - -  Net income (loss) available to common unitholders for basic earnings per unit $ 5,871 $ 130,945 $ (141,008)   Weighted average common units 100,410 100,245 100,222   Basic EPU :  Net income (loss) available to common unitholders for basic earnings per unit $ 0.06 $ 1.31 $ (1.41)    Year Ended December 31,  Computation of Diluted EPU 2017 2016 2015  Net income (loss) available to common unitholders for basic earnings per unit $ 5,871 $ 130,945 $ (141,008)   Weighted average common unit 100,703 100,498 100,222   Diluted EPU :  Net income (loss) available to common unitholders for basic earnings per unit $ 0.06 $ 1.30 $ (1.41)  The following schedule reconciles the weighted average units used in the basic EPU calculation to the units used in the diluted EPU calculation: (in thousands)    Year Ended December 31,  2017 2016 2015  Basic EPU units 100,410 100,245 100,222  Add: Restricted Stock Awards 40 43 -  Stock Options 253 210 -  Diluted EPU Units 100,703 100,498 100,222  Contingently issuable shares under the PSU Awards were excluded from the denominator in 2017 , 2016 and 2015 because the criteria had not been met for the periods. Contingently issuable shares under Restricted Stock Awards and all stock options were excluded from the denominator in 2015 as such securities were anti-dilutive during the period. Not included in the computations of diluted EPU were 405,000 stock options as such securities were anti-dilutive during the year ended December 31, 2015. Also not included in the computations of diluted EPU were all of the LTIP Units as such securities were anti-dilutive during all periods presented. Unvested restricted stock outstanding as of December 31, 2017 , 2016 and 2015 were 95,801 , 120,245 and 98,669 shares, respectively.  Distributions declared per common unit for the years ended December 31, 2017 , 2016 and 2015 was $ 0.75 , $0.60 and $0.60 per unit, respectively.

Noncontrolling Interests In Sub

Noncontrolling Interests In Subsidiaries	12 Months Ended
	Dec. 31, 2017
Noncontrolling Interest [Line Items]
Noncontrolling Interests In Subsidiaries	16. NONCONTROLLING INTERESTS IN SUBSIDIARIES  Noncontrolling interests in subsidiaries in the accompanying consolidated financial statements relate to (i) common units and LTIP units in the Operating Partnership, held by parties other than the General Partner (“Limited Partners”) , and (ii) interests in consolidated joint ventures for the portion of such ventures not owned by the Company.  Pursuant to ASC 810, Consolidation, on the accounting and reporting for noncontrolling interests and changes in ownership interests of a subsidiary , changes in a parent’s ownership interest (and transactions with noncontrolling interest unitholders in the subsidiary) while the parent retains its controlling interest in its subsidiary should be accounted for as equity transactions. The carrying value of the noncontrolling interest shall be adjusted to reflect the change in its ownership interest in the subsidiary, with the offset to equity attributable to the parent. Accordingly, as a result of equity transactions which caused changes in ownership percentages between Mack-Cali Realty Corporation stockholders’ equity and noncontrolling interests in the Operating Partnership that occurred during the year ended December 31, 2017 , the Company has decreased noncontrolling interests in the Operating Partnership and increased additional paid-in capital in Mack-Cali Realty Corporation stockholders’ equity by approximately $4.6 million a s of December 31, 201 6 .  NONCONTROLLING INTEREST IN OPERATING PARTNERSHIP (applicable only to General Partner)  Common Units Certain individuals and entities own common units in the Operating Partnership. A common unit and a share of Common Stock of the General Partner have substantially the same economic characteristics in as much as they effectively share equally in the net income or loss of the Operating Partnership. Common unitholders have the right to redeem their common units, subject to certain restrictions. The redemption is required to be satisfied in shares of Common Stock, cash, or a combination thereof, calculated as follows: one share of the General Partner ’s Common Stock, or cash equal to the fair market value of a share of the General Partner ’s Common Stock at the time of redemption, for each common unit. The General Partner , in its sole discretion, determines the form of redemption of common units (i.e., whether a common unitholder receives Common Stock, cash, or any combination thereof). If the General Partner elects to satisfy the redemption with shares of Common Stock as opposed to cash, it is obligated to issue shares of its Common Stock to the redeeming unitholder. Regardless of the rights described above, the common unitholders may not put their units for cash to the General Partner or the Operating Partnership under any circumstances. When a unitholder redeems a common unit, noncontrolling interest in the Operating Partnership is reduced and Mack-Cali Realty Corporation Stockholders’ equity is increased.  LTIP Units On March 8, 2016, the Company granted 2016 LTIP Awards to senior management of the Company, including the General Partner’s executive officers. On April 4, 2017, the Company granted 2017 LTIP Awards to senior management of the Company, including the General Partner’s executive officers. All of the 2016 LTIP Awards and 2017 LTIP Awards will be in the form of units in the Operating Partnership. See Note 15: Mack-Cali Realty Corporation Stockholders’ Equity and Mack-Cali Realty, L.P.’s Partners’ Capital – Long-Term Incentive Plan Awards.  LTIP Units are designed to qualify as “profits interests” in the Operating Partnership for federal income tax purposes. As a general matter, the profits interests characteristics of the LTIP Units mean that initially they will not be economically equivalent in value to a common unit. If and when events specified by applicable tax regulations occur, LTIP Units can over time increase in value up to the point where they are equivalent to common units on a one-for-one basis. After LTIP Units are fully vested, and to the extent the special tax rules applicable to profits interests have allowed them to become equivalent in value to common units, LTIP Units may be converted on a one-for-one basis into common units. Common units in turn have a one-for-one relationship in value with shares of the General Partner’s common stock, and are redeemable on a one-for-one basis for cash or, at the election of the Company, shares of the General Partner’s common stock.  Unit Transactions The following table sets forth the changes in noncontrolling interests in subsidiaries which relate to the common units and LTIP units in the Operating Partnership for the year s ended December 31, 2017 , 2016 and 2015 :     Common LTIP  Units Units  Balance at January 1, 2015 11,083,876 -  Redemption of common units for shares of common stock (567,032) -  Balance at December 31, 2015 10,516,844 -  Redemption of common units for shares of common stock (28,739) -  Issuance of units - 657,373  Balance at December 31, 2016 10,488,105 657,373  Redemption of common units for shares of common stock (148,662) -  Issuance of units 99,412 578,323  Cancellation of units - (4,819)   Balance at December 31, 2017 10,438,855 1,230,877  Noncontrolling Interest Ownership in Operating Partnership As of December 31, 2017 and 2016 , the noncontrolling interest common unitholders owned 10.4 percent and 10.5 percent of the Operating Partnership, respectively.  NONCONTROLLING INTEREST IN CONSOLIDATED JOINT VENTURES (applicable to General Partner and Operating Partnership)  The Company consolidates certain joint ventures in which it has ownership interests. Various entities and/or individuals hold noncontrolling interests in these ventures.  In June 2017, the Company acquired the remaining noncontrolling interest in 150 Main Street, LLC, a consolidated joint venture, for cash consideration of $2 million and the issuance of 99,412 Common Units valued at $2.8 million.  PARTICIPATION RIGHTS The Company’s interests in certain real estate projects ( two properties and a future development) each provide for the initial distributions of net cash flow solely to the Company, and thereafter, other parties have participation rights in 50 percent of the excess net cash flow remaining after the distribution to the Company of the aggregate amount equal to the sum of: (a) the Company’s capital contributions, plus (b) an IRR of 10 percent per annum.
Mack-Cali Realty LP [Member]
Noncontrolling Interest [Line Items]
Noncontrolling Interests In Subsidiaries	16. NONCONTROLLING INTERESTS IN SUBSIDIARIES  Noncontrolling interests in subsidiaries in the accompanying consolidated financial statements relate to (i) common units and LTIP units in the Operating Partnership, held by parties other than the General Partner (“Limited Partners”) , and (ii) interests in consolidated joint ventures for the portion of such ventures not owned by the Company.  Pursuant to ASC 810, Consolidation, on the accounting and reporting for noncontrolling interests and changes in ownership interests of a subsidiary , changes in a parent’s ownership interest (and transactions with noncontrolling interest unitholders in the subsidiary) while the parent retains its controlling interest in its subsidiary should be accounted for as equity transactions. The carrying value of the noncontrolling interest shall be adjusted to reflect the change in its ownership interest in the subsidiary, with the offset to equity attributable to the parent. Accordingly, as a result of equity transactions which caused changes in ownership percentages between Mack-Cali Realty Corporation stockholders’ equity and noncontrolling interests in the Operating Partnership that occurred during the year ended December 31, 2017 , the Company has decreased noncontrolling interests in the Operating Partnership and increased additional paid-in capital in Mack-Cali Realty Corporation stockholders’ equity by approximately $4.6 million a s of December 31, 201 6 .  NONCONTROLLING INTEREST IN OPERATING PARTNERSHIP (applicable only to General Partner)  Common Units Certain individuals and entities own common units in the Operating Partnership. A common unit and a share of Common Stock of the General Partner have substantially the same economic characteristics in as much as they effectively share equally in the net income or loss of the Operating Partnership. Common unitholders have the right to redeem their common units, subject to certain restrictions. The redemption is required to be satisfied in shares of Common Stock, cash, or a combination thereof, calculated as follows: one share of the General Partner ’s Common Stock, or cash equal to the fair market value of a share of the General Partner ’s Common Stock at the time of redemption, for each common unit. The General Partner , in its sole discretion, determines the form of redemption of common units (i.e., whether a common unitholder receives Common Stock, cash, or any combination thereof). If the General Partner elects to satisfy the redemption with shares of Common Stock as opposed to cash, it is obligated to issue shares of its Common Stock to the redeeming unitholder. Regardless of the rights described above, the common unitholders may not put their units for cash to the General Partner or the Operating Partnership under any circumstances. When a unitholder redeems a common unit, noncontrolling interest in the Operating Partnership is reduced and Mack-Cali Realty Corporation Stockholders’ equity is increased.  LTIP Units On March 8, 2016, the Company granted 2016 LTIP Awards to senior management of the Company, including the General Partner’s executive officers. On April 4, 2017, the Company granted 2017 LTIP Awards to senior management of the Company, including the General Partner’s executive officers. All of the 2016 LTIP Awards and 2017 LTIP Awards will be in the form of units in the Operating Partnership. See Note 15: Mack-Cali Realty Corporation Stockholders’ Equity and Mack-Cali Realty, L.P.’s Partners’ Capital – Long-Term Incentive Plan Awards.  LTIP Units are designed to qualify as “profits interests” in the Operating Partnership for federal income tax purposes. As a general matter, the profits interests characteristics of the LTIP Units mean that initially they will not be economically equivalent in value to a common unit. If and when events specified by applicable tax regulations occur, LTIP Units can over time increase in value up to the point where they are equivalent to common units on a one-for-one basis. After LTIP Units are fully vested, and to the extent the special tax rules applicable to profits interests have allowed them to become equivalent in value to common units, LTIP Units may be converted on a one-for-one basis into common units. Common units in turn have a one-for-one relationship in value with shares of the General Partner’s common stock, and are redeemable on a one-for-one basis for cash or, at the election of the Company, shares of the General Partner’s common stock.  Unit Transactions The following table sets forth the changes in noncontrolling interests in subsidiaries which relate to the common units and LTIP units in the Operating Partnership for the year s ended December 31, 2017 , 2016 and 2015 :     Common LTIP  Units Units  Balance at January 1, 2015 11,083,876 -  Redemption of common units for shares of common stock (567,032) -  Balance at December 31, 2015 10,516,844 -  Redemption of common units for shares of common stock (28,739) -  Issuance of units - 657,373  Balance at December 31, 2016 10,488,105 657,373  Redemption of common units for shares of common stock (148,662) -  Issuance of units 99,412 578,323  Cancellation of units - (4,819)   Balance at December 31, 2017 10,438,855 1,230,877  Noncontrolling Interest Ownership in Operating Partnership As of December 31, 2017 and 2016 , the noncontrolling interest common unitholders owned 10.4 percent and 10.5 percent of the Operating Partnership, respectively.  NONCONTROLLING INTEREST IN CONSOLIDATED JOINT VENTURES (applicable to General Partner and Operating Partnership)  The Company consolidates certain joint ventures in which it has ownership interests. Various entities and/or individuals hold noncontrolling interests in these ventures.  In June 2017, the Company acquired the remaining noncontrolling interest in 150 Main Street, LLC, a consolidated joint venture, for cash consideration of $2 million and the issuance of 99,412 Common Units valued at $2.8 million.  PARTICIPATION RIGHTS The Company’s interests in certain real estate projects ( two properties and a future development) each provide for the initial distributions of net cash flow solely to the Company, and thereafter, other parties have participation rights in 50 percent of the excess net cash flow remaining after the distribution to the Company of the aggregate amount equal to the sum of: (a) the Company’s capital contributions, plus (b) an IRR of 10 percent per annum.

Segment Reporting

Segment Reporting	12 Months Ended
	Dec. 31, 2017
Segment Reporting Information [Line Items]
Segment Reporting	1 7 . SEGMENT REPORTING  The Company operates in two business segments: (i) commercial and other real estate and (ii) multi-family real estate and services. The Company provides leasing, property management, acquisition, development, construction and tenant-related services for its commercial and other real estate and multi-family real estate portfolio. The Company’s multi ‑family services business also provides similar services for third parties. The Company had no revenues from foreign countries recorded for the year s ended December 31, 2017 , 2016 and 2015 . The Company had no long lived assets in foreign locations as of December 31, 2017 and 2016 . The accounting policies of the segments are the same as those described in Note 2: Significant Accounting Policies, excluding depreciation and amortization.  The Company evaluates performance based upon net operating income from the combined properties and operations in each of its real estate segments (commercial and other real estate , and multi-family real estate and services) .  Selected results of operations for the years ended December 31, 2017 , 2016 and 2015 , and selected asset information as of December 31, 2017 and 2016 regarding the Company’s operating segments are as follows. Amounts for prior periods have been restated to conform to the current period segment reporting presentation: (dollars in thousands)    Commercial Multi-family Corporate Total  & Other Real Estate Real Estate & Services (d) & Other (e) Company  Total revenues:  2017 $ 522,223 $ 90,654 $ 3,323 $ 616,200  2016 541,271 69,873 2,254 613,398  2015 534,549 57,293 3,041 594,883   Total operating and  interest expenses (a):  2017 $ 238,055 $ 63,589 $ 94,662 $ 396,306  2016 263,663 60,646 91,042 415,351  2015 262,768 52,018 110,365 425,151   Equity in earnings (loss) of  unconsolidated joint ventures:  2017 $ 1,644 $ (7,725) $ - $ (6,081)  2016 23,796 (5,008) - 18,788  2015 5,118 (8,290) - (3,172)  -  Net operating income (loss) (b):  2017 $ 285,812 $ 19,340 $ (91,339) $ 213,813  2016 301,404 4,219 (88,788) 216,835  2015 276,899 (3,015) (107,324) 166,560   Total assets:  2017 $ 2,915,646 $ 1,937,708 $ 104,531 $ 4,957,885  2016 2,947,400 1,287,824 61,542 4,296,766   Total long-lived assets (c):  2017 $ 2,613,815 $ 1,645,410 $ 31,901 $ 4,291,126  2016 2,621,467 994,484 583 3,616,534   Total investments in  unconsolidated joint ventures:  2017 $ 15,143 $ 237,321 $ 162 $ 252,626  2016 81,549 238,498 - 320,047   (a) Total operating and interest expenses represent the sum of: real estate taxes; utilities; operating services; real estate services expenses; general and administrative , acquisition-related costs and interest expense (net of interest income). All interest expense, net of interest and other investment income, (including for property-level mortgages) is excluded from segment amounts and classified in Corporate & Other for all periods. (b) Net operating income represents total revenues less total operating and interest expenses (as defined in Note “a”), plus equity in earnings (loss) of unconsolidated joint ventures, for the period. (c) Long-lived assets are comprised of net investment in rental property, unbilled rents receivable and goodwill. (d) Segment assets and operations were owned through a consolidated variable interest entity commencing in February 2017. (e) Corporate & Other represents all corporate-level items (including interest and other investment income, interest expense, non-property general and administrative expense) as well as intercompany eliminations necessary to reconcile to consolidated Company totals. Mack-Cali Realty Corporation The following schedule reconciles net operating income to net income available to common shareholders: (dollars in thousands)      Year Ended December 31,  2017 2016 2015  Net operating income $ 213,813 $ 216,835 $ 166,560  Add (deduct):  Depreciation and amortization (205,169) (186,684) (170,402)  Gain on change of control of interests - 15,347 -  Realized gains (losses) and unrealized losses on disposition of  rental property, net 2,364 109,666 53,261  Gain on sale of investment in unconsolidated joint venture 23,131 5,670 6,448  Loss from extinguishment of debt, net (421) (30,540) -  Impairments - - (197,919)  Net income (loss) 33,718 130,294 (142,052)  Noncontrolling interest in consolidated joint ventures 1,018 651 1,044  Noncontrolling interest in Operating Partnership (2,711) (13,721) 15,256  Redeemable noncontrolling interest (8,840) - -  Net income (loss) available to common shareholders $ 23,185 $ 117,224 $ (125,752) Mack-Cali Realty, L.P. The following schedule reconciles net operating income to net income available to common unitholders: (dollars in thousands)     Year Ended December 31,  2017 2016 2015  Net operating income $ 213,813 $ 216,835 $ 166,560  Add (deduct):  Depreciation and amortization (205,169) (186,684) (170,402)  Gain on change of control of interests - 15,347 -  Realized gains (losses) and unrealized losses on disposition of  rental property, net 2,364 109,666 53,261  Gain on sale of investment in unconsolidated joint venture 23,131 5,670 6,448  Loss from extinguishment of debt, net (421) (30,540) -  Impairments - - (197,919)  Net income (loss) 33,718 130,294 (142,052)  Noncontrolling interest in consolidated joint ventures 1,018 651 1,044  Redeemable noncontrolling interest (8,840) -  Net income (loss) available to common unitholders $ 25,896 $ 130,945 $ (141,008) 
Mack-Cali Realty LP [Member]
Segment Reporting Information [Line Items]
Segment Reporting	1 7 . SEGMENT REPORTING  The Company operates in two business segments: (i) commercial and other real estate and (ii) multi-family real estate and services. The Company provides leasing, property management, acquisition, development, construction and tenant-related services for its commercial and other real estate and multi-family real estate portfolio. The Company’s multi ‑family services business also provides similar services for third parties. The Company had no revenues from foreign countries recorded for the year s ended December 31, 2017 , 2016 and 2015 . The Company had no long lived assets in foreign locations as of December 31, 2017 and 2016 . The accounting policies of the segments are the same as those described in Note 2: Significant Accounting Policies, excluding depreciation and amortization.  The Company evaluates performance based upon net operating income from the combined properties and operations in each of its real estate segments (commercial and other real estate , and multi-family real estate and services) .  Selected results of operations for the years ended December 31, 2017 , 2016 and 2015 , and selected asset information as of December 31, 2017 and 2016 regarding the Company’s operating segments are as follows. Amounts for prior periods have been restated to conform to the current period segment reporting presentation: (dollars in thousands)    Commercial Multi-family Corporate Total  & Other Real Estate Real Estate & Services (d) & Other (e) Company  Total revenues:  2017 $ 522,223 $ 90,654 $ 3,323 $ 616,200  2016 541,271 69,873 2,254 613,398  2015 534,549 57,293 3,041 594,883   Total operating and  interest expenses (a):  2017 $ 238,055 $ 63,589 $ 94,662 $ 396,306  2016 263,663 60,646 91,042 415,351  2015 262,768 52,018 110,365 425,151   Equity in earnings (loss) of  unconsolidated joint ventures:  2017 $ 1,644 $ (7,725) $ - $ (6,081)  2016 23,796 (5,008) - 18,788  2015 5,118 (8,290) - (3,172)  -  Net operating income (loss) (b):  2017 $ 285,812 $ 19,340 $ (91,339) $ 213,813  2016 301,404 4,219 (88,788) 216,835  2015 276,899 (3,015) (107,324) 166,560   Total assets:  2017 $ 2,915,646 $ 1,937,708 $ 104,531 $ 4,957,885  2016 2,947,400 1,287,824 61,542 4,296,766   Total long-lived assets (c):  2017 $ 2,613,815 $ 1,645,410 $ 31,901 $ 4,291,126  2016 2,621,467 994,484 583 3,616,534   Total investments in  unconsolidated joint ventures:  2017 $ 15,143 $ 237,321 $ 162 $ 252,626  2016 81,549 238,498 - 320,047   (a) Total operating and interest expenses represent the sum of: real estate taxes; utilities; operating services; real estate services expenses; general and administrative , acquisition-related costs and interest expense (net of interest income). All interest expense, net of interest and other investment income, (including for property-level mortgages) is excluded from segment amounts and classified in Corporate & Other for all periods. (b) Net operating income represents total revenues less total operating and interest expenses (as defined in Note “a”), plus equity in earnings (loss) of unconsolidated joint ventures, for the period. (c) Long-lived assets are comprised of net investment in rental property, unbilled rents receivable and goodwill. (d) Segment assets and operations were owned through a consolidated variable interest entity commencing in February 2017. (e) Corporate & Other represents all corporate-level items (including interest and other investment income, interest expense, non-property general and administrative expense) as well as intercompany eliminations necessary to reconcile to consolidated Company totals. Mack-Cali Realty Corporation The following schedule reconciles net operating income to net income available to common shareholders: (dollars in thousands)      Year Ended December 31,  2017 2016 2015  Net operating income $ 213,813 $ 216,835 $ 166,560  Add (deduct):  Depreciation and amortization (205,169) (186,684) (170,402)  Gain on change of control of interests - 15,347 -  Realized gains (losses) and unrealized losses on disposition of  rental property, net 2,364 109,666 53,261  Gain on sale of investment in unconsolidated joint venture 23,131 5,670 6,448  Loss from extinguishment of debt, net (421) (30,540) -  Impairments - - (197,919)  Net income (loss) 33,718 130,294 (142,052)  Noncontrolling interest in consolidated joint ventures 1,018 651 1,044  Noncontrolling interest in Operating Partnership (2,711) (13,721) 15,256  Redeemable noncontrolling interest (8,840) - -  Net income (loss) available to common shareholders $ 23,185 $ 117,224 $ (125,752) Mack-Cali Realty, L.P. The following schedule reconciles net operating income to net income available to common unitholders: (dollars in thousands)     Year Ended December 31,  2017 2016 2015  Net operating income $ 213,813 $ 216,835 $ 166,560  Add (deduct):  Depreciation and amortization (205,169) (186,684) (170,402)  Gain on change of control of interests - 15,347 -  Realized gains (losses) and unrealized losses on disposition of  rental property, net 2,364 109,666 53,261  Gain on sale of investment in unconsolidated joint venture 23,131 5,670 6,448  Loss from extinguishment of debt, net (421) (30,540) -  Impairments - - (197,919)  Net income (loss) 33,718 130,294 (142,052)  Noncontrolling interest in consolidated joint ventures 1,018 651 1,044  Redeemable noncontrolling interest (8,840) -  Net income (loss) available to common unitholders $ 25,896 $ 130,945 $ (141,008) 

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2017
Related Party Transactions	18. RELATED PARTY TRANSACTIONS  William L. Mack, Chairman of the Board of Directors of the General Partner, David S. Mack, a director of the General Partner, and Earle I. Mack, a former director of the General Partner, are the executive officers, directors and stockholders of a corporation that leases approximately 7,034 square feet at one of the Company’s office properties, which is scheduled to expire in May 2018 , subject to two , three -year renewal options. The Company has recognized $187,000 , $193,000 and $204,000 in revenue under this lease for the years ended December 31, 2017 , 2016 and 2015 , respectively, and had no accounts receivable from the corporation as of December 31, 2017 and 2016 .  Certain executive officers of the Company’s Roseland subsidiary and/or their family members (“RG”) directly or indirectly hold small noncontrolling interests in a certain consolidated joint venture. Additionally, the Company earned $1,873,000 , $2,464,000 , and $2,542,000 from entities in which RG has ownership interests for the years ended December 31, 2017 , 2016 and 2015 , respectively.
Mack-Cali Realty LP [Member]
Related Party Transactions	18. RELATED PARTY TRANSACTIONS  William L. Mack, Chairman of the Board of Directors of the General Partner, David S. Mack, a director of the General Partner, and Earle I. Mack, a former director of the General Partner, are the executive officers, directors and stockholders of a corporation that leases approximately 7,034 square feet at one of the Company’s office properties, which is scheduled to expire in May 2018 , subject to two , three -year renewal options. The Company has recognized $187,000 , $193,000 and $204,000 in revenue under this lease for the years ended December 31, 2017 , 2016 and 2015 , respectively, and had no accounts receivable from the corporation as of December 31, 2017 and 2016 .  Certain executive officers of the Company’s Roseland subsidiary and/or their family members (“RG”) directly or indirectly hold small noncontrolling interests in a certain consolidated joint venture. Additionally, the Company earned $1,873,000 , $2,464,000 , and $2,542,000 from entities in which RG has ownership interests for the years ended December 31, 2017 , 2016 and 2015 , respectively.

Condensed Quarterly Financial I

Condensed Quarterly Financial Information	12 Months Ended
	Dec. 31, 2017
Condensed Quarterly Financial Information	1 9 . CONDENSED QUARTERLY FINANCIAL INFORMATION (unaudited)  Mack-Cali Realty Corporation The following summarizes the condensed quarterly financial information for the Company: (dollars in thousands)      Quarter Ended 2017 December 31 September 30 June 30 March 31  Total revenues $ 143,529 $ 160,018 $ 162,766 $ 149,887  Net income (loss) $ 5,411 $ 44,703 $ (39,125) $ 22,729  Net income (loss) available to common shareholders $ 2,582 $ 38,054 $ (37,330) $ 19,879  `  Basic earnings per common share:  Net income (loss) available to common shareholders $ (0.01) $ 0.39 $ (0.44) $ 0.11   Diluted earnings per common share:  Net income (loss) available to common shareholders $ (0.01) $ 0.39 $ (0.44) $ 0.11       Quarter Ended 2016 December 31 September 30 June 30 March 31  Total revenues $ 153,731 $ 157,517 $ 149,227 $ 152,923  Net income (loss) $ 16,764 $ (9,605) $ 54,366 $ 68,769  Net income (loss) available to common shareholders $ 15,181 $ (8,541) $ 48,393 $ 62,191   Basic earnings per common share:  Net income (loss) available to common shareholders $ 0.17 $ (0.10) $ 0.54 $ 0.69   Diluted earnings per common share:  Net income (loss) available to common shareholders $ 0.17 $ (0.10) $ 0.54 $ 0.69   Mack-Cali Realty, L.P. The following summarizes the condensed quarterly financial information for the Company: (dollars in thousands)     Quarter Ended 2017 December 31 September 30 June 30 March 31  Total revenues $ 143,529 $ 160,018 $ 162,766 $ 149,887  Net income (loss) $ 5,411 $ 44,703 $ (39,125) $ 22,729  Net income (loss) available to common unitholders $ 2,881 $ 42,467 $ (41,626) $ 22,174   Basic earnings per common unit:  Net income (loss) available to common unitholders $ (0.01) $ 0.39 $ (0.44) $ 0.11   Diluted earnings per common units:  Net income (loss) available to common unitolders $ (0.01) $ 0.39 $ (0.44) $ 0.11       Quarter Ended 2016 December 31 September 30 June 30 March 31  Total revenues $ 153,731 $ 157,517 $ 149,227 $ 152,923  Net income (loss) $ 16,764 $ (9,605) $ 54,366 $ 68,769  Net income (loss) available to common unitholders $ 16,955 $ (9,540) $ 54,055 $ 69,475   Basic earnings per common unit:  Net income (loss) available to common unitholders $ 0.17 $ (0.10) $ 0.54 $ 0.69   Diluted earnings per common unit:  Net income (loss) available to common unitholders $ 0.17 $ (0.10) $ 0.54 $ 0.69 
Mack-Cali Realty LP [Member]
Condensed Quarterly Financial Information	1 9 . CONDENSED QUARTERLY FINANCIAL INFORMATION (unaudited)  Mack-Cali Realty Corporation The following summarizes the condensed quarterly financial information for the Company: (dollars in thousands)      Quarter Ended 2017 December 31 September 30 June 30 March 31  Total revenues $ 143,529 $ 160,018 $ 162,766 $ 149,887  Net income (loss) $ 5,411 $ 44,703 $ (39,125) $ 22,729  Net income (loss) available to common shareholders $ 2,582 $ 38,054 $ (37,330) $ 19,879  `  Basic earnings per common share:  Net income (loss) available to common shareholders $ (0.01) $ 0.39 $ (0.44) $ 0.11   Diluted earnings per common share:  Net income (loss) available to common shareholders $ (0.01) $ 0.39 $ (0.44) $ 0.11       Quarter Ended 2016 December 31 September 30 June 30 March 31  Total revenues $ 153,731 $ 157,517 $ 149,227 $ 152,923  Net income (loss) $ 16,764 $ (9,605) $ 54,366 $ 68,769  Net income (loss) available to common shareholders $ 15,181 $ (8,541) $ 48,393 $ 62,191   Basic earnings per common share:  Net income (loss) available to common shareholders $ 0.17 $ (0.10) $ 0.54 $ 0.69   Diluted earnings per common share:  Net income (loss) available to common shareholders $ 0.17 $ (0.10) $ 0.54 $ 0.69   Mack-Cali Realty, L.P. The following summarizes the condensed quarterly financial information for the Company: (dollars in thousands)     Quarter Ended 2017 December 31 September 30 June 30 March 31  Total revenues $ 143,529 $ 160,018 $ 162,766 $ 149,887  Net income (loss) $ 5,411 $ 44,703 $ (39,125) $ 22,729  Net income (loss) available to common unitholders $ 2,881 $ 42,467 $ (41,626) $ 22,174   Basic earnings per common unit:  Net income (loss) available to common unitholders $ (0.01) $ 0.39 $ (0.44) $ 0.11   Diluted earnings per common units:  Net income (loss) available to common unitolders $ (0.01) $ 0.39 $ (0.44) $ 0.11       Quarter Ended 2016 December 31 September 30 June 30 March 31  Total revenues $ 153,731 $ 157,517 $ 149,227 $ 152,923  Net income (loss) $ 16,764 $ (9,605) $ 54,366 $ 68,769  Net income (loss) available to common unitholders $ 16,955 $ (9,540) $ 54,055 $ 69,475   Basic earnings per common unit:  Net income (loss) available to common unitholders $ 0.17 $ (0.10) $ 0.54 $ 0.69   Diluted earnings per common unit:  Net income (loss) available to common unitholders $ 0.17 $ (0.10) $ 0.54 $ 0.69 

Real Estate Investments And Acc

Real Estate Investments And Accumulated Depreciation	12 Months Ended
	Dec. 31, 2017
Real Estate Investments And Accumulated Depreciation	    MACK-CALI REALTY CORPORATION, MACK-CALI REALTY, L.P. AND SUBSIDIARIES  REAL ESTATE INVESTMENTS AND ACCUMULATED DEPRECIATION  December 31, 2017  (dollars in thousands)  SCHEDULE III  Gross Amount at Which  Costs Carried at Close of  Initial Costs Capitalized Period (a)  Property Year Related Building and Subsequent to Building and Accumulated  Property Location Type Built Acquired Encumbrances Land Improvements Acquisition(e) Land Improvements Total (d) Depreciation (b)   NEW JERSEY  Bergen County  Fort Lee  One Bridge Plaza Office 1981 1996 - 2,439 24,462 7,482 2,439 31,944 34,383 16,885  2115 Linwood Avenue Office 1981 1998 - 474 4,419 7,756 474 12,175 12,649 5,035   Essex County  Millburn  150 J.F. Kennedy Parkway Office 1980 1997 - 12,606 50,425 15,149 12,606 65,574 78,180 30,833  Roseland  75 Livingston Avenue Office 1985 2009 4,478 1,900 6,312 (1,725) 1,281 5,206 6,487 1,387  51 J.F. Kennedy Parkway Office 1988 2017 69,393 5,873 100,359 - 5,873 100,359 106,232 3,115  101 J.F. Kennedy Parkway Office 1981 2017 29,169 4,380 59,730 - 4,380 59,730 64,110 1,844  103 J.F. Kennedy Parkway Office 1981 2017 24,852 3,158 50,813 - 3,158 50,813 53,971 1,555   Hudson County  Hoboken  111 River Street Office 2002 2016 - 204 198,609 14,771 - 213,584 213,584 8,680  Jersey City  Harborside Plaza 1 Office 1983 1996 - 3,923 51,013 27,936 3,923 78,949 82,872 44,931  Harborside Plaza 2 Office 1990 1996 - 17,655 101,546 40,011 8,364 150,848 159,212 64,754  Harborside Plaza 3 Office 1990 1996 - 17,655 101,878 39,678 8,363 150,848 159,211 64,754  Harborside Plaza 4A Office 2000 2000 - 1,244 56,144 8,452 1,244 64,596 65,840 29,121  Harborside Plaza 5 Office 2002 2002 209,180 6,218 170,682 61,569 5,705 232,764 238,469 98,606  101 Hudson Street Office 1992 2005 248,261 45,530 271,376 16,952 45,530 288,328 333,858 93,337  Rosegarden Monaco Multi-Family 2011 2017 169,988 58,761 240,870 11 58,761 240,881 299,642 4,590  Weehawken  100 Avenue at Port Imperial Other 2016 2016 - 350 - 4,205 471 4,084 4,555 186  500 Avenue at Port Imperial Other 2013 2013 36,260 13,099 56,669 (20,540) 13,099 36,129 49,228 3,982   Mercer County  Hamilton Township  600 Horizon Drive Office/Flex 2002 2002 - - 7,549 1,189 685 8,053 8,738 3,218  700 Horizon Drive Office 2007 2007 - 490 43 16,663 865 16,331 17,196 5,046  Princeton  100 Overlook Center Office 1988 1997 - 2,378 21,754 4,245 2,378 25,999 28,377 12,960  5 Vaughn Drive Office 1987 1995 - 657 9,800 1,983 657 11,783 12,440 6,547   Middlesex County  Edison  333 Thornall Street Office 1984 2015 - 5,542 40,762 2,344 5,542 43,106 48,648 3,319  343 Thornall Street Office 1991 2006 - 6,027 39,101 11,532 6,027 50,633 56,660 14,840  Iselin  101 Wood Avenue South Office 1990 2016 - 8,509 72,738 692 7,384 74,555 81,939 4,315  New Brunswick  Richmond Court Multi-Family 1997 2013 - 2,992 13,534 1,908 2,992 15,442 18,434 1,417  Riverwatch Commons Multi-Family 1995 2013 - 4,169 18,974 2,177 4,169 21,151 25,320 1,951  Plainsboro  500 College Road East (c) Office 1984 1998 614 20,626 5,708 614 26,334 26,948 13,152  Woodbridge  581 Main Street Office 1991 1997 - 3,237 12,949 24,191 8,115 32,262 40,377 15,056   Monmouth County  Holmdel  23 Main Street Office 1977 2005 27,078 4,336 19,544 13,944 4,336 33,488 37,824 15,515  Middletown  One River Center, Building 1 Office 1983 2004 10,362 3,070 17,414 11,421 2,451 29,454 31,905 9,154  One River Center, Building 2 Office 1983 2004 11,624 2,468 15,043 4,101 2,452 19,160 21,612 7,093  One River Center, Building 3 Office 1984 2004 18,472 4,051 24,790 5,687 4,627 29,901 34,528 10,588  Neptune  3600 Route 66 Office 1989 1995 - 1,098 18,146 11,471 1,098 29,617 30,715 14,193  Red Bank  100 Schultz Drive Office 1989 2017 - - - 8,743 1,953 6,790 8,743 556  200 Schultz Drive Office 1989 2017 - - - 10,443 2,184 8,259 10,443 495       MACK-CALI REALTY CORPORATION, MACK-CALI REALTY, L.P. AND SUBSIDIARIES  REAL ESTATE INVESTMENTS AND ACCUMULATED DEPRECIATION  December 31, 2017  (dollars in thousands)  SCHEDULE III  Gross Amount at Which  Costs Carried at Close of  Initial Costs Capitalized Period (a)  Property Year Related Building and Subsequent to Building and Accumulated  Property Location Type Built Acquired Encumbrances Land Improvements Acquisition(e) Land Improvements Total (d) Depreciation (b)   Morris County  Florham Park  325 Columbia Parkway Office 1987 1994 - 1,564 - 18,368 1,564 18,368 19,932 12,583  Madison  1 Giralda Farms Office 1982 2017 - - - 30,515 3,370 27,145 30,515 1,014  7 Giralda Farms Office 1997 2017 - - - 43,066 5,402 37,664 43,066 1,246  Morris Plains  201 Littleton Road Office 1979 1997 - 2,407 9,627 3,132 2,407 12,759 15,166 6,416  Parsippany  4 Campus Drive Office 1983 2001 - 5,213 20,984 4,117 5,213 25,101 30,314 10,513  6 Campus Drive Office 1983 2001 - 4,411 17,796 3,550 4,411 21,346 25,757 9,177  7 Campus Drive Office 1982 1998 - 1,932 27,788 6,573 1,932 34,361 36,293 17,234  8 Campus Drive Office 1987 1998 - 1,865 35,456 11,139 1,865 46,595 48,460 20,169  9 Campus Drive Office 1983 2001 - 3,277 11,796 22,609 5,842 31,840 37,682 12,352  2 Dryden Way Office 1990 1998 - 778 420 110 778 530 1,308 302  4 Gatehall Drive Office 1988 2000 - 8,452 33,929 5,302 8,452 39,231 47,683 17,628  2 Hilton Court Office 1991 1998 - 1,971 32,007 4,474 1,971 36,481 38,452 18,874  1 Sylvan Way Office 1989 1998 - 1,689 24,699 2,253 1,021 27,620 28,641 13,301  3 Sylvan Way Office 1988 2015 - 5,590 4,710 4,033 5,590 8,743 14,333 280  5 Sylvan Way Office 1989 1998 - 1,160 25,214 4,769 1,161 29,982 31,143 13,950  7 Sylvan Way Office 1987 1998 - 2,084 26,083 14,805 2,084 40,888 42,972 14,057  5 Wood Hollow Road Office 1979 2004 - 5,302 26,488 20,963 5,302 47,451 52,753 19,473   Somerset County  Bridgewater  721 Route 202/206 Office 1989 1997 - 6,730 26,919 (5,309) 5,067 23,273 28,340 12,109   Union County  Rahway  Park Square Multi-Family 2011 2013 26,526 4,000 40,670 294 4,000 40,964 44,964 4,192   NEW YORK  Westchester County  Eastchester  Quarry Place at Tuckahoe Multi-Family 2016 2016 40,367 5,585 3,400 48,632 5,585 52,032 57,617 1,163  Elmsford  11 Clearbrook Road Office/Flex 1974 1997 - 149 2,159 578 149 2,737 2,886 1,452  75 Clearbrook Road Office/Flex 1990 1997 - 2,314 4,716 57 2,314 4,773 7,087 2,500  100 Clearbrook Road Office 1975 1997 - 220 5,366 1,674 220 7,040 7,260 3,422  125 Clearbrook Road Office/Flex 2002 2002 - 1,055 3,676 (252) 1,055 3,424 4,479 1,500  150 Clearbrook Road Office/Flex 1975 1997 - 497 7,030 2,156 497 9,186 9,683 4,616  175 Clearbrook Road Office/Flex 1973 1997 - 655 7,473 953 655 8,426 9,081 4,444  200 Clearbrook Road Office/Flex 1974 1997 - 579 6,620 1,667 579 8,287 8,866 4,066  250 Clearbrook Road Office/Flex 1973 1997 - 867 8,647 2,434 867 11,081 11,948 5,458  50 Executive Boulevard Office/Flex 1969 1997 - 237 2,617 540 237 3,157 3,394 1,620  77 Executive Boulevard Office/Flex 1977 1997 - 34 1,104 177 34 1,281 1,315 695  85 Executive Boulevard Office/Flex 1968 1997 - 155 2,507 538 155 3,045 3,200 1,560  101 Executive Boulevard Office 1971 1997 - 267 5,838 (6,004) 101 - 101 -  300 Executive Boulevard Office/Flex 1970 1997 - 460 3,609 302 460 3,911 4,371 2,015  350 Executive Boulevard Office/Flex 1970 1997 - 100 1,793 175 100 1,968 2,068 1,085  399 Executive Boulevard Office/Flex 1962 1997 - 531 7,191 163 531 7,354 7,885 3,885  400 Executive Boulevard Office/Flex 1970 1997 - 2,202 1,846 1,140 2,202 2,986 5,188 1,662  500 Executive Boulevard Office/Flex 1970 1997 - 258 4,183 384 258 4,567 4,825 2,514  525 Executive Boulevard Office/Flex 1972 1997 - 345 5,499 900 345 6,399 6,744 3,520  1 Warehouse Lane (c) Industrial/Warehouse 1957 1997 - 3 268 208 3 476 479 240  2 Warehouse Lane (c) Industrial/Warehouse 1957 1997 - 4 672 341 4 1,013 1,017 444  3 Warehouse Lane (c) Industrial/Warehouse 1957 1997 - 21 1,948 363 21 2,311 2,332 1,314  4 Warehouse Lane (c) Industrial/Warehouse 1957 1997 - 84 13,393 3,665 85 17,057 17,142 8,441  5 Warehouse Lane (c) Industrial/Warehouse 1957 1997 - 19 4,804 884 19 5,688 5,707 3,053  6 Warehouse Lane (c) Industrial/Warehouse 1982 1997 - 10 4,419 2,381 10 6,800 6,810 3,246        MACK-CALI REALTY CORPORATION, MACK-CALI REALTY, L.P. AND SUBSIDIARIES  REAL ESTATE INVESTMENTS AND ACCUMULATED DEPRECIATION  December 31, 2017  (dollars in thousands)  SCHEDULE III  Gross Amount at Which  Costs Carried at Close of  Initial Costs Capitalized Period (a)  Property Year Related Building and Subsequent to Building and Accumulated  Property Location Type Built Acquired Encumbrances Land Improvements Acquisition(e) Land Improvements Total (d) Depreciation (b)   1 Westchester Plaza Office/Flex 1967 1997 - 199 2,023 152 199 2,175 2,374 1,156  2 Westchester Plaza Office/Flex 1968 1997 - 234 2,726 914 234 3,640 3,874 1,806  3 Westchester Plaza Office/Flex 1969 1997 - 655 7,936 1,407 655 9,343 9,998 4,541  4 Westchester Plaza Office/Flex 1969 1997 - 320 3,729 1,979 320 5,708 6,028 2,825  5 Westchester Plaza Office/Flex 1969 1997 - 118 1,949 374 118 2,323 2,441 1,247  6 Westchester Plaza Office/Flex 1968 1997 - 164 1,998 160 164 2,158 2,322 1,124  7 Westchester Plaza Office/Flex 1972 1997 - 286 4,321 1,166 286 5,487 5,773 2,575  8 Westchester Plaza Office/Flex 1971 1997 - 447 5,262 2,127 447 7,389 7,836 3,709  Hawthorne  200 Saw Mill River Road Office/Flex 1965 1997 - 353 3,353 745 353 4,098 4,451 2,037  1 Skyline Drive Office 1980 1997 - 66 1,711 210 66 1,921 1,987 1,049  2 Skyline Drive Office 1987 1997 - 109 3,128 1,474 109 4,602 4,711 2,696  4 Skyline Drive Office/Flex 1987 1997 - 363 7,513 3,071 363 10,584 10,947 6,190  5 Skyline Drive Office/Flex 1980 2001 - 2,219 8,916 1,841 2,219 10,757 12,976 5,495  6 Skyline Drive Office/Flex 1980 2001 - 740 2,971 1,295 740 4,266 5,006 2,582  7 Skyline Drive Office 1987 1998 - 330 13,013 2,929 330 15,942 16,272 7,758  8 Skyline Drive Office/Flex 1985 1997 - 212 4,410 777 212 5,187 5,399 2,893  10 Skyline Drive Office/Flex 1985 1997 - 134 2,799 812 134 3,611 3,745 2,121  11 Skyline Drive (c) Office/Flex 1989 1997 - - 4,788 763 - 5,551 5,551 2,741  12 Skyline Drive (c) Office/Flex 1999 1999 - 1,562 3,254 218 1,320 3,714 5,034 1,790  15 Skyline Drive (c) Office/Flex 1989 1997 - - 7,449 1,749 - 9,198 9,198 4,220  17 Skyline Drive (c) Office 1989 1997 - - 7,269 1,484 - 8,753 8,753 4,540  Tarrytown  230 White Plains Road Retail 1984 1997 - 124 1,845 288 124 2,133 2,257 1,045  White Plains  1 Barker Avenue Office 1975 1997 - 208 9,629 3,248 207 12,878 13,085 6,406  3 Barker Avenue Office 1983 1997 - 122 7,864 2,117 122 9,981 10,103 5,076  Yonkers  100 Corporate Boulevard Office/Flex 1987 1997 - 602 9,910 1,334 602 11,244 11,846 5,973  200 Corporate Boulevard South Office/Flex 1990 1997 - 502 7,575 3,116 502 10,691 11,193 5,159  1 Executive Boulevard Office 1982 1997 - 1,104 11,904 3,815 1,105 15,718 16,823 7,750  2 Executive Boulevard Retail 1986 1997 - 89 2,439 107 89 2,546 2,635 1,324  3 Executive Boulevard Office 1987 1997 - 385 6,256 1,817 385 8,073 8,458 4,219  4 Executive Plaza Office/Flex 1986 1997 - 584 6,134 995 584 7,129 7,713 3,664  6 Executive Plaza Office/Flex 1987 1997 - 546 7,246 2,360 546 9,606 10,152 4,942  1 Odell Plaza Office/Flex 1980 1997 - 1,206 6,815 2,367 1,206 9,182 10,388 4,775  3 Odell Plaza Office 1984 2003 - 1,322 4,777 2,332 1,322 7,109 8,431 3,736  5 Odell Plaza Office/Flex 1983 1997 - 331 2,988 535 331 3,523 3,854 1,990  7 Odell Plaza Office/Flex 1984 1997 - 419 4,418 1,366 419 5,784 6,203 2,886         MACK-CALI REALTY CORPORATION, MACK-CALI REALTY, L.P. AND SUBSIDIARIES  REAL ESTATE INVESTMENTS AND ACCUMULATED DEPRECIATION  December 31, 2017  (dollars in thousands)  SCHEDULE III  Gross Amount at Which  Costs Carried at Close of  Initial Costs Capitalized Period (a)  Property Year Related Building and Subsequent to Building and Accumulated  Property Location Type Built Acquired Encumbrances Land Improvements Acquisition(e) Land Improvements Total (d) Depreciation (b)   CONNECTICUT  Fairfield County  Stamford  419 West Avenue Office/Flex 1986 1997 - 4,538 9,246 482 4,538 9,728 14,266 5,060  500 West Avenue Office/Flex 1988 1997 - 415 1,679 646 415 2,325 2,740 1,098  550 West Avenue Office/Flex 1990 1997 - 1,975 3,856 133 1,975 3,989 5,964 2,065  600 West Avenue Office/Flex 1999 1999 - 2,305 2,863 1,005 2,305 3,868 6,173 1,611  650 West Avenue Office/Flex 1998 1998 - 1,328 - 3,268 1,328 3,268 4,596 1,613   MASSACHUSETTS  Middlesex County  Malden  Chase at Overlook Ridge Multi-Family 2016 2016 74,988 11,072 87,793 269 11,072 88,062 99,134 4,577  Chase II at Overlook Ridge Multi-Family 2016 2016 59,697 10,755 10,846 52,598 10,755 63,444 74,199 1,390   Suffolk County  East Boston  Portside at Pier One Multi-Family 2016 2016 58,566 - 73,713 9 - 73,722 73,722 3,908  Revere  Alterra at Overlook Ridge IA Multi-Family 2004 2013 40,061 9,042 50,671 956 9,042 51,627 60,669 6,559  Alterra at Overlook Ridge II Multi-Family 2008 2013 59,309 12,055 71,409 299 12,056 71,707 83,763 9,058   Projects Under Development  and Developable Land 184,984 399,372 677,593 - 399,372 677,593 1,076,965 33,278   Furniture, Fixtures  and Equipment - - - 30,247 - 30,247 30,247 11,031   TOTALS 1,403,615 789,095 3,553,425 760,324 786,789 4,316,055 5,102,844 1,087,083  (a) The aggregate cost for federal income tax purposes at December 31, 2017 was approximately $3.9 billion. (b) Depreciation of buildings and improvements are calculated over lives ranging from the life of the lease to 40 years. (c) This property is located on land leased by the Company. (d) Properties identified as held for sale at December 31, 2017 are excluded. (e) These costs are net of impairments recorded, if any.   MACK-CALI REALTY CORPORATION/MACK-CALI REALTY, L.P. AND SUBSIDIARIES NOTE TO SCHEDULE III    Changes in rental properties and accumulated depreciation for the periods ended December 31, 2017 , 2016 and 2015 are as follows: (dollars in thousands)     2017 2016 2015  Rental Properties  Balance at beginning of year $ 4,804,867 $ 4,807,718 $ 4,958,179  Additions 1,179,365 819,535 219,227  Rental property held for sale (310,089) (79,200) -  Properties sold (538,424) (695,837) (82,015)  Impairments - - (255,849)  Retirements/disposals (32,875) (47,349) (31,824)  Balance at end of year $ 5,102,844 $ 4,804,867 $ 4,807,718    Accumulated Depreciation  Balance at beginning of year $ 1,332,073 $ 1,464,482 $ 1,414,305  Depreciation expense 154,343 151,569 147,447  Rental property held for sale (126,503) (31,792) -  Properties sold (217,625) (204,837) (7,517)  Repurposed buildings (22,330)  Impairments - - (57,929)  Retirements/disposals (32,875) (47,349) (31,824)  Balance at end of year $ 1,087,083 $ 1,332,073 $ 1,464,482   Schadf      
Mack-Cali Realty LP [Member]
Real Estate Investments And Accumulated Depreciation	    MACK-CALI REALTY CORPORATION, MACK-CALI REALTY, L.P. AND SUBSIDIARIES  REAL ESTATE INVESTMENTS AND ACCUMULATED DEPRECIATION  December 31, 2017  (dollars in thousands)  SCHEDULE III  Gross Amount at Which  Costs Carried at Close of  Initial Costs Capitalized Period (a)  Property Year Related Building and Subsequent to Building and Accumulated  Property Location Type Built Acquired Encumbrances Land Improvements Acquisition(e) Land Improvements Total (d) Depreciation (b)   NEW JERSEY  Bergen County  Fort Lee  One Bridge Plaza Office 1981 1996 - 2,439 24,462 7,482 2,439 31,944 34,383 16,885  2115 Linwood Avenue Office 1981 1998 - 474 4,419 7,756 474 12,175 12,649 5,035   Essex County  Millburn  150 J.F. Kennedy Parkway Office 1980 1997 - 12,606 50,425 15,149 12,606 65,574 78,180 30,833  Roseland  75 Livingston Avenue Office 1985 2009 4,478 1,900 6,312 (1,725) 1,281 5,206 6,487 1,387  51 J.F. Kennedy Parkway Office 1988 2017 69,393 5,873 100,359 - 5,873 100,359 106,232 3,115  101 J.F. Kennedy Parkway Office 1981 2017 29,169 4,380 59,730 - 4,380 59,730 64,110 1,844  103 J.F. Kennedy Parkway Office 1981 2017 24,852 3,158 50,813 - 3,158 50,813 53,971 1,555   Hudson County  Hoboken  111 River Street Office 2002 2016 - 204 198,609 14,771 - 213,584 213,584 8,680  Jersey City  Harborside Plaza 1 Office 1983 1996 - 3,923 51,013 27,936 3,923 78,949 82,872 44,931  Harborside Plaza 2 Office 1990 1996 - 17,655 101,546 40,011 8,364 150,848 159,212 64,754  Harborside Plaza 3 Office 1990 1996 - 17,655 101,878 39,678 8,363 150,848 159,211 64,754  Harborside Plaza 4A Office 2000 2000 - 1,244 56,144 8,452 1,244 64,596 65,840 29,121  Harborside Plaza 5 Office 2002 2002 209,180 6,218 170,682 61,569 5,705 232,764 238,469 98,606  101 Hudson Street Office 1992 2005 248,261 45,530 271,376 16,952 45,530 288,328 333,858 93,337  Rosegarden Monaco Multi-Family 2011 2017 169,988 58,761 240,870 11 58,761 240,881 299,642 4,590  Weehawken  100 Avenue at Port Imperial Other 2016 2016 - 350 - 4,205 471 4,084 4,555 186  500 Avenue at Port Imperial Other 2013 2013 36,260 13,099 56,669 (20,540) 13,099 36,129 49,228 3,982   Mercer County  Hamilton Township  600 Horizon Drive Office/Flex 2002 2002 - - 7,549 1,189 685 8,053 8,738 3,218  700 Horizon Drive Office 2007 2007 - 490 43 16,663 865 16,331 17,196 5,046  Princeton  100 Overlook Center Office 1988 1997 - 2,378 21,754 4,245 2,378 25,999 28,377 12,960  5 Vaughn Drive Office 1987 1995 - 657 9,800 1,983 657 11,783 12,440 6,547   Middlesex County  Edison  333 Thornall Street Office 1984 2015 - 5,542 40,762 2,344 5,542 43,106 48,648 3,319  343 Thornall Street Office 1991 2006 - 6,027 39,101 11,532 6,027 50,633 56,660 14,840  Iselin  101 Wood Avenue South Office 1990 2016 - 8,509 72,738 692 7,384 74,555 81,939 4,315  New Brunswick  Richmond Court Multi-Family 1997 2013 - 2,992 13,534 1,908 2,992 15,442 18,434 1,417  Riverwatch Commons Multi-Family 1995 2013 - 4,169 18,974 2,177 4,169 21,151 25,320 1,951  Plainsboro  500 College Road East (c) Office 1984 1998 614 20,626 5,708 614 26,334 26,948 13,152  Woodbridge  581 Main Street Office 1991 1997 - 3,237 12,949 24,191 8,115 32,262 40,377 15,056   Monmouth County  Holmdel  23 Main Street Office 1977 2005 27,078 4,336 19,544 13,944 4,336 33,488 37,824 15,515  Middletown  One River Center, Building 1 Office 1983 2004 10,362 3,070 17,414 11,421 2,451 29,454 31,905 9,154  One River Center, Building 2 Office 1983 2004 11,624 2,468 15,043 4,101 2,452 19,160 21,612 7,093  One River Center, Building 3 Office 1984 2004 18,472 4,051 24,790 5,687 4,627 29,901 34,528 10,588  Neptune  3600 Route 66 Office 1989 1995 - 1,098 18,146 11,471 1,098 29,617 30,715 14,193  Red Bank  100 Schultz Drive Office 1989 2017 - - - 8,743 1,953 6,790 8,743 556  200 Schultz Drive Office 1989 2017 - - - 10,443 2,184 8,259 10,443 495       MACK-CALI REALTY CORPORATION, MACK-CALI REALTY, L.P. AND SUBSIDIARIES  REAL ESTATE INVESTMENTS AND ACCUMULATED DEPRECIATION  December 31, 2017  (dollars in thousands)  SCHEDULE III  Gross Amount at Which  Costs Carried at Close of  Initial Costs Capitalized Period (a)  Property Year Related Building and Subsequent to Building and Accumulated  Property Location Type Built Acquired Encumbrances Land Improvements Acquisition(e) Land Improvements Total (d) Depreciation (b)   Morris County  Florham Park  325 Columbia Parkway Office 1987 1994 - 1,564 - 18,368 1,564 18,368 19,932 12,583  Madison  1 Giralda Farms Office 1982 2017 - - - 30,515 3,370 27,145 30,515 1,014  7 Giralda Farms Office 1997 2017 - - - 43,066 5,402 37,664 43,066 1,246  Morris Plains  201 Littleton Road Office 1979 1997 - 2,407 9,627 3,132 2,407 12,759 15,166 6,416  Parsippany  4 Campus Drive Office 1983 2001 - 5,213 20,984 4,117 5,213 25,101 30,314 10,513  6 Campus Drive Office 1983 2001 - 4,411 17,796 3,550 4,411 21,346 25,757 9,177  7 Campus Drive Office 1982 1998 - 1,932 27,788 6,573 1,932 34,361 36,293 17,234  8 Campus Drive Office 1987 1998 - 1,865 35,456 11,139 1,865 46,595 48,460 20,169  9 Campus Drive Office 1983 2001 - 3,277 11,796 22,609 5,842 31,840 37,682 12,352  2 Dryden Way Office 1990 1998 - 778 420 110 778 530 1,308 302  4 Gatehall Drive Office 1988 2000 - 8,452 33,929 5,302 8,452 39,231 47,683 17,628  2 Hilton Court Office 1991 1998 - 1,971 32,007 4,474 1,971 36,481 38,452 18,874  1 Sylvan Way Office 1989 1998 - 1,689 24,699 2,253 1,021 27,620 28,641 13,301  3 Sylvan Way Office 1988 2015 - 5,590 4,710 4,033 5,590 8,743 14,333 280  5 Sylvan Way Office 1989 1998 - 1,160 25,214 4,769 1,161 29,982 31,143 13,950  7 Sylvan Way Office 1987 1998 - 2,084 26,083 14,805 2,084 40,888 42,972 14,057  5 Wood Hollow Road Office 1979 2004 - 5,302 26,488 20,963 5,302 47,451 52,753 19,473   Somerset County  Bridgewater  721 Route 202/206 Office 1989 1997 - 6,730 26,919 (5,309) 5,067 23,273 28,340 12,109   Union County  Rahway  Park Square Multi-Family 2011 2013 26,526 4,000 40,670 294 4,000 40,964 44,964 4,192   NEW YORK  Westchester County  Eastchester  Quarry Place at Tuckahoe Multi-Family 2016 2016 40,367 5,585 3,400 48,632 5,585 52,032 57,617 1,163  Elmsford  11 Clearbrook Road Office/Flex 1974 1997 - 149 2,159 578 149 2,737 2,886 1,452  75 Clearbrook Road Office/Flex 1990 1997 - 2,314 4,716 57 2,314 4,773 7,087 2,500  100 Clearbrook Road Office 1975 1997 - 220 5,366 1,674 220 7,040 7,260 3,422  125 Clearbrook Road Office/Flex 2002 2002 - 1,055 3,676 (252) 1,055 3,424 4,479 1,500  150 Clearbrook Road Office/Flex 1975 1997 - 497 7,030 2,156 497 9,186 9,683 4,616  175 Clearbrook Road Office/Flex 1973 1997 - 655 7,473 953 655 8,426 9,081 4,444  200 Clearbrook Road Office/Flex 1974 1997 - 579 6,620 1,667 579 8,287 8,866 4,066  250 Clearbrook Road Office/Flex 1973 1997 - 867 8,647 2,434 867 11,081 11,948 5,458  50 Executive Boulevard Office/Flex 1969 1997 - 237 2,617 540 237 3,157 3,394 1,620  77 Executive Boulevard Office/Flex 1977 1997 - 34 1,104 177 34 1,281 1,315 695  85 Executive Boulevard Office/Flex 1968 1997 - 155 2,507 538 155 3,045 3,200 1,560  101 Executive Boulevard Office 1971 1997 - 267 5,838 (6,004) 101 - 101 -  300 Executive Boulevard Office/Flex 1970 1997 - 460 3,609 302 460 3,911 4,371 2,015  350 Executive Boulevard Office/Flex 1970 1997 - 100 1,793 175 100 1,968 2,068 1,085  399 Executive Boulevard Office/Flex 1962 1997 - 531 7,191 163 531 7,354 7,885 3,885  400 Executive Boulevard Office/Flex 1970 1997 - 2,202 1,846 1,140 2,202 2,986 5,188 1,662  500 Executive Boulevard Office/Flex 1970 1997 - 258 4,183 384 258 4,567 4,825 2,514  525 Executive Boulevard Office/Flex 1972 1997 - 345 5,499 900 345 6,399 6,744 3,520  1 Warehouse Lane (c) Industrial/Warehouse 1957 1997 - 3 268 208 3 476 479 240  2 Warehouse Lane (c) Industrial/Warehouse 1957 1997 - 4 672 341 4 1,013 1,017 444  3 Warehouse Lane (c) Industrial/Warehouse 1957 1997 - 21 1,948 363 21 2,311 2,332 1,314  4 Warehouse Lane (c) Industrial/Warehouse 1957 1997 - 84 13,393 3,665 85 17,057 17,142 8,441  5 Warehouse Lane (c) Industrial/Warehouse 1957 1997 - 19 4,804 884 19 5,688 5,707 3,053  6 Warehouse Lane (c) Industrial/Warehouse 1982 1997 - 10 4,419 2,381 10 6,800 6,810 3,246        MACK-CALI REALTY CORPORATION, MACK-CALI REALTY, L.P. AND SUBSIDIARIES  REAL ESTATE INVESTMENTS AND ACCUMULATED DEPRECIATION  December 31, 2017  (dollars in thousands)  SCHEDULE III  Gross Amount at Which  Costs Carried at Close of  Initial Costs Capitalized Period (a)  Property Year Related Building and Subsequent to Building and Accumulated  Property Location Type Built Acquired Encumbrances Land Improvements Acquisition(e) Land Improvements Total (d) Depreciation (b)   1 Westchester Plaza Office/Flex 1967 1997 - 199 2,023 152 199 2,175 2,374 1,156  2 Westchester Plaza Office/Flex 1968 1997 - 234 2,726 914 234 3,640 3,874 1,806  3 Westchester Plaza Office/Flex 1969 1997 - 655 7,936 1,407 655 9,343 9,998 4,541  4 Westchester Plaza Office/Flex 1969 1997 - 320 3,729 1,979 320 5,708 6,028 2,825  5 Westchester Plaza Office/Flex 1969 1997 - 118 1,949 374 118 2,323 2,441 1,247  6 Westchester Plaza Office/Flex 1968 1997 - 164 1,998 160 164 2,158 2,322 1,124  7 Westchester Plaza Office/Flex 1972 1997 - 286 4,321 1,166 286 5,487 5,773 2,575  8 Westchester Plaza Office/Flex 1971 1997 - 447 5,262 2,127 447 7,389 7,836 3,709  Hawthorne  200 Saw Mill River Road Office/Flex 1965 1997 - 353 3,353 745 353 4,098 4,451 2,037  1 Skyline Drive Office 1980 1997 - 66 1,711 210 66 1,921 1,987 1,049  2 Skyline Drive Office 1987 1997 - 109 3,128 1,474 109 4,602 4,711 2,696  4 Skyline Drive Office/Flex 1987 1997 - 363 7,513 3,071 363 10,584 10,947 6,190  5 Skyline Drive Office/Flex 1980 2001 - 2,219 8,916 1,841 2,219 10,757 12,976 5,495  6 Skyline Drive Office/Flex 1980 2001 - 740 2,971 1,295 740 4,266 5,006 2,582  7 Skyline Drive Office 1987 1998 - 330 13,013 2,929 330 15,942 16,272 7,758  8 Skyline Drive Office/Flex 1985 1997 - 212 4,410 777 212 5,187 5,399 2,893  10 Skyline Drive Office/Flex 1985 1997 - 134 2,799 812 134 3,611 3,745 2,121  11 Skyline Drive (c) Office/Flex 1989 1997 - - 4,788 763 - 5,551 5,551 2,741  12 Skyline Drive (c) Office/Flex 1999 1999 - 1,562 3,254 218 1,320 3,714 5,034 1,790  15 Skyline Drive (c) Office/Flex 1989 1997 - - 7,449 1,749 - 9,198 9,198 4,220  17 Skyline Drive (c) Office 1989 1997 - - 7,269 1,484 - 8,753 8,753 4,540  Tarrytown  230 White Plains Road Retail 1984 1997 - 124 1,845 288 124 2,133 2,257 1,045  White Plains  1 Barker Avenue Office 1975 1997 - 208 9,629 3,248 207 12,878 13,085 6,406  3 Barker Avenue Office 1983 1997 - 122 7,864 2,117 122 9,981 10,103 5,076  Yonkers  100 Corporate Boulevard Office/Flex 1987 1997 - 602 9,910 1,334 602 11,244 11,846 5,973  200 Corporate Boulevard South Office/Flex 1990 1997 - 502 7,575 3,116 502 10,691 11,193 5,159  1 Executive Boulevard Office 1982 1997 - 1,104 11,904 3,815 1,105 15,718 16,823 7,750  2 Executive Boulevard Retail 1986 1997 - 89 2,439 107 89 2,546 2,635 1,324  3 Executive Boulevard Office 1987 1997 - 385 6,256 1,817 385 8,073 8,458 4,219  4 Executive Plaza Office/Flex 1986 1997 - 584 6,134 995 584 7,129 7,713 3,664  6 Executive Plaza Office/Flex 1987 1997 - 546 7,246 2,360 546 9,606 10,152 4,942  1 Odell Plaza Office/Flex 1980 1997 - 1,206 6,815 2,367 1,206 9,182 10,388 4,775  3 Odell Plaza Office 1984 2003 - 1,322 4,777 2,332 1,322 7,109 8,431 3,736  5 Odell Plaza Office/Flex 1983 1997 - 331 2,988 535 331 3,523 3,854 1,990  7 Odell Plaza Office/Flex 1984 1997 - 419 4,418 1,366 419 5,784 6,203 2,886         MACK-CALI REALTY CORPORATION, MACK-CALI REALTY, L.P. AND SUBSIDIARIES  REAL ESTATE INVESTMENTS AND ACCUMULATED DEPRECIATION  December 31, 2017  (dollars in thousands)  SCHEDULE III  Gross Amount at Which  Costs Carried at Close of  Initial Costs Capitalized Period (a)  Property Year Related Building and Subsequent to Building and Accumulated  Property Location Type Built Acquired Encumbrances Land Improvements Acquisition(e) Land Improvements Total (d) Depreciation (b)   CONNECTICUT  Fairfield County  Stamford  419 West Avenue Office/Flex 1986 1997 - 4,538 9,246 482 4,538 9,728 14,266 5,060  500 West Avenue Office/Flex 1988 1997 - 415 1,679 646 415 2,325 2,740 1,098  550 West Avenue Office/Flex 1990 1997 - 1,975 3,856 133 1,975 3,989 5,964 2,065  600 West Avenue Office/Flex 1999 1999 - 2,305 2,863 1,005 2,305 3,868 6,173 1,611  650 West Avenue Office/Flex 1998 1998 - 1,328 - 3,268 1,328 3,268 4,596 1,613   MASSACHUSETTS  Middlesex County  Malden  Chase at Overlook Ridge Multi-Family 2016 2016 74,988 11,072 87,793 269 11,072 88,062 99,134 4,577  Chase II at Overlook Ridge Multi-Family 2016 2016 59,697 10,755 10,846 52,598 10,755 63,444 74,199 1,390   Suffolk County  East Boston  Portside at Pier One Multi-Family 2016 2016 58,566 - 73,713 9 - 73,722 73,722 3,908  Revere  Alterra at Overlook Ridge IA Multi-Family 2004 2013 40,061 9,042 50,671 956 9,042 51,627 60,669 6,559  Alterra at Overlook Ridge II Multi-Family 2008 2013 59,309 12,055 71,409 299 12,056 71,707 83,763 9,058   Projects Under Development  and Developable Land 184,984 399,372 677,593 - 399,372 677,593 1,076,965 33,278   Furniture, Fixtures  and Equipment - - - 30,247 - 30,247 30,247 11,031   TOTALS 1,403,615 789,095 3,553,425 760,324 786,789 4,316,055 5,102,844 1,087,083  (a) The aggregate cost for federal income tax purposes at December 31, 2017 was approximately $3.9 billion. (b) Depreciation of buildings and improvements are calculated over lives ranging from the life of the lease to 40 years. (c) This property is located on land leased by the Company. (d) Properties identified as held for sale at December 31, 2017 are excluded. (e) These costs are net of impairments recorded, if any.   MACK-CALI REALTY CORPORATION/MACK-CALI REALTY, L.P. AND SUBSIDIARIES NOTE TO SCHEDULE III    Changes in rental properties and accumulated depreciation for the periods ended December 31, 2017 , 2016 and 2015 are as follows: (dollars in thousands)     2017 2016 2015  Rental Properties  Balance at beginning of year $ 4,804,867 $ 4,807,718 $ 4,958,179  Additions 1,179,365 819,535 219,227  Rental property held for sale (310,089) (79,200) -  Properties sold (538,424) (695,837) (82,015)  Impairments - - (255,849)  Retirements/disposals (32,875) (47,349) (31,824)  Balance at end of year $ 5,102,844 $ 4,804,867 $ 4,807,718    Accumulated Depreciation  Balance at beginning of year $ 1,332,073 $ 1,464,482 $ 1,414,305  Depreciation expense 154,343 151,569 147,447  Rental property held for sale (126,503) (31,792) -  Properties sold (217,625) (204,837) (7,517)  Repurposed buildings (22,330)  Impairments - - (57,929)  Retirements/disposals (32,875) (47,349) (31,824)  Balance at end of year $ 1,087,083 $ 1,332,073 $ 1,464,482   Schadf      

Mortgage Loans On Real Estate

Mortgage Loans On Real Estate	12 Months Ended
	Dec. 31, 2017
Mortgage Loans on Real Estate [Abstract]
Mortgage Loans on Real Estate, by Loan Disclosure [Text Block]	  MACK-CALI REALTY CORPORATION/MACK-CALI REALTY, L.P. AND SUBSIDIARIES SCHEDULE IV – MORTGAGE LOANS ON REAL ESTATE As of December 31, 2017 (in thousands)       Face Amount  of Mortgages or  Interest Interest Final Periodic Maximum Carrying  Type of Accrual Payment Maturity Payment Prior Available Amount of  Loan/Borrower Description Location Rate Rate Date Term (a) Liens Credit Mortgages   Mortgage Loan:  Borrower A Land Jersey City, NJ 5.85 % 5.85 % 07/21/19 P&I - $ 44,695 $ 45,734   Total $ 44,695 $ 45,734   (a) P&I = Principal & Interest at maturity   The following table reconciles mortgage loans from January 1, 2017 to December 31, 2017 (in thousands) :       2017  Balance at January 1 $ -  Additions  New mortgage loan 44,695  Accrued interest 1,039  Balance at December 31, $ 45,734  

Significant Accounting Polici29

Significant Accounting Policies (Policy)	12 Months Ended
	Dec. 31, 2017
Significant Accounting Policies [Line Items]
Rental Property	Rental Property Rental properties are stated at cost less accumulated depreciation and amortization. Costs directly related to the acquisition, development and construction of rental properties are capitalized. Acquisition–related costs were expensed as incurred through December 31, 2016. The Company early adopted the recently issued FASB guidance Accounting Standards Update (“ASU”) 2017-01 on January 1, 2017 which revises the definition of a business and is expected to result in more transactions to be accounted for as asset acquisitions and significantly limit transactions that would be accounted for as business combinations. Where an acquisition has been determined to be an asset acquisition, acquisition-related costs are capitalized. Capitalized development and construction costs include pre-construction costs essential to the development of the property, development and construction costs, interest, property taxes, insurance, salaries and other project costs incurred during the period of development. Capitalized development and construction salaries and related costs approximated $ 2.2 million, $ 2.6 million and $4.2 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. Included in total rental property is construction, tenant improvement and development in-progress of $ 559.5 million and $ 361.1 million as of December 31, 2017 and 2016 , respectively. Ordinary repairs and maintenance are expensed as incurred; major replacements and betterments, which improve or extend the life of the asset, are capitalized and depreciated over their estimated useful lives. Fully-depreciated assets are removed from the accounts.  The Company considers a construction project as substantially completed and held available for occupancy upon the substantial completion of tenant improvements, but no later than one year from cessation of major construction activity (as distinguished from activities such as routine maintenance and cleanup). If portions of a rental project are substantially completed and occupied by tenants, or held available for occupancy, and other portions have not yet reached that stage, the substantially completed portions are accounted for as a separate project. The Company allocates costs incurred between the portions under construction and the portions substantially completed and held available for occupancy, primarily based on a percentage of the relative square footage of each portion, and capitalizes only those costs associated with the portion under construction.  Properties are depreciated using the straight-line method over the estimated useful lives of the assets. The estimated useful lives are as follows:   Leasehold interests Remaining lease term Buildings and improvements 5 to 40 years Tenant improvements The shorter of the term of the  related lease or useful life Furniture, fixtures and equipment 5 to 10 years  Upon acquisition of rental property, the Company estimates the fair value of acquired tangible assets, consisting of land, building and improvements, and identified intangible assets and liabilities assumed, generally consisting of the fair value of (i) above and below market leases, (ii) in-place leases and (iii) tenant relationships. The Company allocates the purchase price to the assets acquired and liabilities assumed based on their fair values. The Company records goodwill or a gain on bargain purchase (if any) if the net assets acquired/liabilities assumed differ from the purchase consideration of a business transaction.  In estimating the fair value of the tangible and intangible assets acquired, the Company considers information obtained about each property as a result of its due diligence and marketing and leasing activities, and utilizes various valuation methods, such as estimated cash flow projections utilizing appropriate discount and capitalization rates, estimates of replacement costs net of depreciation, and available market information. The fair value of the tangible assets of an acquired property considers the value of the property as if it were vacant.  Above-market and below-market lease values for acquired properties are initially recorded based on the present value (using a discount rate which reflects the risks associated with the leases acquired) of the difference between (i) the contractual amounts to be paid pursuant to each in-place lease and (ii) management’s estimate of fair market lease rates for each corresponding in-place lease, measured over a period equal to the remaining term of the lease for above-market leases and the remaining initial term plus the term of any below-market fixed rate renewal options for below-market leases. The capitalized above-market lease values are amortized as a reduction of base rental revenue over the remaining terms of the respective leases, and the capitalized below-market lease values are amortized as an increase to base rental revenue over the remaining initial terms plus the terms of any below-market fixed rate renewal options of the respective leases.  Other intangible assets acquired include amounts for in-place lease values and tenant relationship values, which are based on management’s evaluation of the specific characteristics of each tenant’s lease and the Company’s overall relationship with the respective tenant. Factors to be considered by management in its analysis of in-place lease values include an estimate of carrying costs during hypothetical expected lease-up periods considering current market conditions, and costs to execute similar leases. In estimating carrying costs, management includes real estate taxes, insurance and other operating expenses and estimates of lost rentals at market rates during the expected lease-up periods, depending on local market conditions. In estimating costs to execute similar leases, management considers leasing commissions, legal and other related expenses. Characteristics considered by management in valuing tenant relationships include the nature and extent of the Company’s existing business relationships with the tenant, growth prospects for developing new business with the tenant, the tenant’s credit quality and expectations of lease renewals. The value of in-place leases are amortized to expense over the remaining initial terms of the respective leases. The value of tenant relationship intangibles are amortized to expense over the anticipated life of the relationships.  On a periodic basis, management assesses whether there are any indicators that the value of the Company’s rental properties held for use may be impaired. In addition to identifying any specific circumstances which may affect a property or properties, management considers other criteria for determining which properties may require assessment for potential impairment. The criteria considered by management include reviewing low leased percentages, significant near-term lease expirations, current and historical operating and/or cash flow losses, near-term mortgage debt maturities and/or other factors, including those that might impact the Company’s intent and ability to hold the property. A property’s value is impaired only if management’s estimate of the aggregate future cash flows (undiscounted and without interest charges) to be generated by the property is less than the carrying value of the property. To the extent impairment has occurred, the impairment loss shall be measured as the excess of the carrying value of the property over the fair value of the property. The Company’s estimates of aggregate future cash flows expected to be generated by each property are based on a number of assumptions. These assumptions are generally based on management’s experience in its local real estate markets and the effects of current market conditions. The assumptions are subject to economic and market uncertainties including, among others, demand for space, competition for tenants, changes in market rental rates, and costs to operate each property. As these factors are difficult to predict and are subject to future events that may alter management’s assumptions, the future cash flows estimated by management in its impairment analyses may not be achieved, and actual losses or impairments may be realized in the future. 
Rental Property Held For Sale	Rental Property Held for Sale When assets are identified by management as held for sale, the Company discontinues depreciating the assets and estimates the sales price, net of selling costs, of such assets. The Company generally considers assets to be held for sale when the transaction has received appropriate corporate authority, and there are no significant contingencies relating to the sale. If, in management’s opinion, the estimated net sales price, net of selling costs, of the assets which have been identified as held for sale is less than the carrying value of the assets, a valuation allowance (which is recorded as unrealized losses on disposition of rental property) is established. If circumstances arise that previously were considered unlikely and, as a result, the Company decides not to sell a property previously classified as held for sale, the property is reclassified as held and used. A property that is reclassified is measured and recorded individually at the lower of (a) its carrying value before the property was classified as held for sale, adjusted for any depreciation (amortization) expense that would have been recognized had the property been continuously classified as held and used, or (b) the fair value at the date of the subsequent decision not to sell. 
Investments In Unconsolidated Joint Ventures	Investments in Unconsolidated Joint Ventures The Company accounts for its investments in unconsolidated joint ventures under the equity method of accounting. The Company applies the equity method by initially recording these investments at cost, as Investments in Unconsolidated Joint Ventures, subsequently adjusted for equity in earnings and cash contributions and distributions. The outside basis portion of the Company’s joint ventures is amortized over the anticipated useful lives of the underlying ventures’ tangible and intangible assets acquired and liabilities assumed. Generally, the Company would discontinue applying the equity method when the investment (and any advances) is reduced to zero and would not provide for additional losses unless the Company has guaranteed obligations of the venture or is otherwise committed to providing further financial support for the investee. If the venture subsequently generates income, the Company only recognizes its share of such income to the extent it exceeds its share of previously unrecognized losses.  If the venture subsequently makes distributions and the Company does not have an implied or actual commitment to support the operations of the venture, including a general partner interest in the investee, the Company will not record a basis less than zero, rather such amounts will be recorded as equity in earnings of unconsolidated joint ventures. On a periodic basis, management assesses whether there are any indicators that the value of the Company’s investments in unconsolidated joint ventures may be impaired. An investment is impaired only if management’s estimate of the value of the investment is less than the carrying value of the investment, and such decline in value is deemed to be other than temporary. To the extent impairment has occurred, the loss shall be measured as the excess of the carrying value of the investment over the value of the investment. The Company’s estimates of value for each investment (particularly in real estate joint ventures) are based on a number of assumptions that are subject to economic and market uncertainties including, among others, demand for space, competition for tenants, changes in market rental rates, and operating costs. As these factors are difficult to predict and are subject to future events that may alter management’s assumptions, the values estimated by management in its impairment analyses may not be realized, and actual losses or impairment may be realized in the future. See Note 4: Investments in Unconsolidated Joint Ventures.
Cash And Cash Equivalents	Cash and Cash Equivalents All highly liquid investments with an original maturity of three months or less when purchased are considered to be cash equivalents.
Deferred Financing Costs	 Deferred Financing Costs Costs incurred in obtaining financing are capitalized and amortized over the term of the related indebtedness. Deferred financing costs are presented in the balance sheet as a direct deduction from the carrying value of the debt liability to which they relate, except deferred financing costs related to the revolving credit facility, which are presented in deferred charges, goodwill and other assets. In all cases, amortization of such costs is included in interest expense and was $ 4,612,000 , $ 4,582,000 and $ 3,790,000 for the years ended December 31, 2017 , 2016 and 2015 , respectively. If a financing obligation is extinguished early, any unamortized deferred financing costs are written off and included in gains (losses) from extinguishment of debt. Included in loss from extinguishment of debt, net of gains, of $0.4 million, $30.5 million and zero for the years ended December 31, 2017 , 2016 and 2015 were unamortized deferred financing costs which were written off amounting to $0.4 million, $ 0.7 million and zero , respectively.
Deferred Leasing Costs	Deferred Leasing Costs Costs incurred in connection with successfully executed commercial leases are capitalized and amortized on a straight-line basis over the terms of the related leases and included in depreciation and amortization. Unamortized deferred leasing costs are charged to amortization expense upon early termination of the lease. Certain employees of the Company are compensated for providing leasing services to the Properties. The portion of such compensation related to commercial leases, which is capitalized and amortized, and included in deferred charges, goodwill and other assets, net was approximately $ 3,146,000 , $ 3,270,000 and $ 3,521,000 for the years ended December 31, 2017 , 2016 and 2015 , respectively.
Goodwill	Goodwill Goodwill represents the excess of the purchase price over the fair value of net tangible and intangible assets acquired in a business combination. Goodwill is allocated to various reporting units, as applicable. Each of the Company’s segments consists of a reporting unit. Goodwill is not amortized. Management performs an annual impairment test for goodwill during the fourth quarter and between annual tests, management evaluates the recoverability of goodwill whenever events or changes in circumstances indicate that the carrying value of goodwill may not be fully recoverable. In its impairment tests of goodwill, management first assesses qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying value. If based on this assessment, management determines that the fair value of the reporting unit is not less than its carrying value, then performing the additional two-step impairment test is unnecessary. If the carrying value of goodwill exceeds its fair value, an impairment charge is recognized. The Company determined that its goodwill was not impaired at December 31, 2017 after management performed its impairment tests.
Derivative Instruments	Derivative Instruments The Company measures derivative instruments, including certain derivative instruments embedded in other contracts, at fair value and records them as an asset or liability, depending on the Company’s rights or obligations under the applicable derivative contract. For derivatives designated and qualifying as fair value hedges, the changes in the fair value of both the derivative instrument and the hedged item are recorded in earnings. For derivatives designated as cash flow hedges, the effective portions of the derivative are reported in other comprehensive income (“OCI”) and are subsequently reclassified into earnings when the hedged item affects earnings. Changes in fair value of derivative instruments not designated as hedging and ineffective portions of hedges are recognized in earnings in the affected period.
Revenue Recognition	Revenue Recognition Base rental revenue is recognized on a straight-line basis over the terms of the respective leases. Unbilled rents receivable represents the cumulative amount by which straight-line rental revenue exceeds rents currently billed in accordance with the lease agreements.  Above-market and below-market lease values for acquired properties are initially recorded based on the present value (using a discount rate which reflects the risks associated with the leases acquired) of the difference between (i) the contractual amounts to be paid pursuant to each in-place lease and (ii) management’s estimate of fair market lease rates for each corresponding in-place lease, measured over a period equal to the remaining term of the lease for above-market leases and the remaining initial term plus the term of any below-market fixed-rate renewal options for below-market leases. The capitalized above-market lease values for acquired properties are amortized as a reduction of base rental revenue over the remaining terms of the respective leases, and the capitalized below-market lease values are amortized as an increase to base rental revenue over the remaining initial terms plus the terms of any below-market fixed-rate renewal options of the respective leases.  Escalations and recoveries from tenants are received from tenants for certain costs as provided in the lease agreements. These costs generally include real estate taxes, utilities, insurance, common area maintenance and other recoverable costs. See Note 13: Tenant Leases.  Real estate services revenue includes property management, development, construction and leasing commission fees and other services, and payroll and related costs reimbursed from clients. Fee income derived from the Company’s unconsolidated joint ventures (which are capitalized by such ventures) are recognized to the extent attributable to the unaffiliated ownership interests.  Parking income includes income from parking spaces leased to tenants and others.  Other income includes income from tenants for additional services arranged for by the Company and income from tenants for early lease terminations.   
Allowance For Doubtful Accounts	Allowance for Doubtful Accounts Management performs a detailed review of amounts due from tenants to determine if an allowance for doubtful accounts is required based on factors affecting the collectability of the accounts receivable balances. The factors considered by management in determining which individual tenant receivable balances, or aggregate receivable balances, require a collectability allowance include the age of the receivable, the tenant’s payment history, the nature of the charges, any communications regarding the charges and other related information. Management’s estimate of the allowance for doubtful accounts requires management to exercise significant judgment about the timing, frequency and severity of collection losses, which affects the allowance and net income.
Income And Other Taxes	Income and Other Taxes The General Partner has elected to be taxed as a REIT under Sections 856 through 860 of the Internal Revenue Code of 1986, as amended (the “IRS Code”). As a REIT, the General Partner generally will not be subject to corporate federal income tax on net income that it currently distributes to its shareholders, provided that the General Partner satisfies certain organizational and operational requirements including the requirement to distribute at least 90 percent of its REIT taxable income (determined by excluding any net capital gains) to its shareholders. If and to the extent the General Partner retains and does not distribute any net capital gains, the General Partner will be required to pay federal, state and local taxes, as applicable, on such net capital gains at the rate applicable to capital gains of a corporation.  The Operating Partnership is a partnership, and, as a result, all income and losses of the partnership are allocated to the partners for inclusion in their respective tax returns. Accordingly, no provision or benefit for income taxes has been made in the accompanying financial statements.  As of December 31, 2017 , the estimated net basis of the rental property for federal income tax purposes was lower than the net assets as reported in the Operating Partnership’s financial statements by approximately $231,067,000 . The Operating Partnership’s taxable income for the year ended December 31, 2017 was estimated to be approximately $97,037,000 and for the years ended December 31, 2016 and 2015 was approximately $30,208,000 and $63,285,000 , respectively. The differences between book income and taxable income primarily result from differences in depreciation expenses, the recording of rental income, differences in the deductibility of certain expenses for tax purposes, differences in revenue recognition and the rules for tax purposes of a property exchange.  The General Partner has elected to treat certain of its corporate subsidiaries as taxable REIT subsidiaries (each a “TRS”). In general, a TRS of the General Partner may perform additional services for tenants of the Company and generally may engage in any real estate or non-real estate related business (except for the operation or management of health care facilities or lodging facilities or the providing to any person, under a franchise, license or otherwise, rights to any brand name under which any lodging facility or health care facility is operated). A TRS is subject to corporate federal income tax. The General Partner has conducted business through its TRS entities for certain property management, development, construction and other related services, as well as to hold a joint venture interest in a hotel and other matters.  The deferred tax balance at December 31, 2017 is $ 11.7 million which has been fully reserved through a valuation allowance. New tax reform legislation enacted in late 2017 reduces the corporate tax rate to 21 percent, effective January 1, 2018. Consequently, the Company’s deferred tax assets were re-measured to reflect the reduction in the future U.S. corporate income tax rate as of the enactment date . As a result, the Company recorded a decrease related to deferred tax assets of $5.3 million and a decrease to the associated valuation allowance of $5.3 million at December 31, 2017. If the General Partner fails to qualify as a REIT in any taxable year, the Company will be subject to federal income tax on its taxable income at regular corporate tax rates. The Company is subject to certain state and local taxes.  Pursuant to the amended provisions related to uncertain tax provisions of ASC 740, Income Taxes, the Company recognized no material adjustments regarding its tax accounting treatment. The Company expects to recognize interest and penalties related to uncertain tax positions, if any, as income tax expense, which is included in general and administrative expense.  In the normal course of business, the Company or one of its subsidiaries is subject to examination by federal, state and local jurisdictions in which it operates, where applicable. As of December 31, 2017 , the tax years that remain subject to examination by the major tax jurisdictions under the statute of limitations are generally from the year 2013 forward. 
Earnings Per Share Or Unit	Earnings Per Share or Unit The Company presents both basic and diluted earnings per share or unit (“EPS or EPU”). Basic EPS or EPU excludes dilution and is computed by dividing net income available to common shareholders or unitholders by the weighted average number of shares or units outstanding for the period. Diluted EPS or EPU reflects the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock, where such exercise or conversion would result in a lower EPS or EPU from continuing operations amount. Shares or Units whose issuance is contingent upon the satisfaction of certain conditions shall be considered outstanding and included in the computation of diluted EPS or EPU as follows (i) if all necessary conditions have been satisfied by the end of the period (the events have occurred), those shares or units shall be included as of the beginning of the period in which the conditions were satisfied (or as of the date of the grant, if later) or (ii) if all necessary conditions have not been satisfied by the end of the period, the number of contingently issuable shares or units included in diluted EPS or EPU shall be based on the number of shares or units, if any, that would be issuable if the end of the reporting period were the end of the contingency period (for example, the number of shares or units that would be issuable based on current period earnings or period-end market price) and if the result would be dilutive. Those contingently issuable shares or units shall be included in the denominator of diluted EPS or EPU as of the beginning of the period (or as of the date of the grant, if later). 
Dividends And Distributions Payable	Dividends and Distributions Payable The dividends and distributions payable at December 31, 2017 represents dividends payable to common shareholders ( 89,914,658 shares) and distributions payable to noncontrolling interest unitholders of the Operating Partnership ( 10,438,855 common units and 1,230,877 LTIP units) for all such holders of record as of January 3, 2018 with respect to the fourth quarter 2017 . The fourth quarter 2017 common stock dividends and unit distributions of $ 0.20 per common share, common unit and LTIP unit were approved by the General Partner’s Board of Directors on December 12, 2017 and paid on January 12, 2018 .  The dividends and distributions payable at December 31, 2016 represents dividends payable to common shareholders ( 89,696,824 shares) and distributions payable to noncontrolling interest unitholders of the Operating Partnership ( 10,488,105 common units and 657,373 LTIP units) for all such holders of record as of January 5, 2017 with respect to the fourth quarter 2016 . The fourth quarter 2016 common stock dividends and unit distributions of $ 0.15 per common share, common unit and LTIP unit were approved by the General Partner’s Board of Directors on December 13, 2016 and paid on January 13, 2017 .  The Company has determined that the $ 0.70 dividend per common share paid during the year ended December 31, 2017 represented 100 percent ordinary income; the $ 0.60 dividend per common share paid during the year ended December 31, 2016 represented 100 percent return of capital; and the $ 0.60 dividend per common share paid during the year ended December 31, 2015 represented approximately 90 percent ordinary income and approximately 10 percent return of capital. 
Costs Incurred For Stock Issuances	Costs Incurred For Stock Issuances Costs incurred in connection with the Company’s stock issuances are reflected as a reduction of additional paid ‑in capital. 
Stock Compensation	Stock Compensation The Company accounts for stock compensation in accordance with the provisions of ASC 718, Compensation-Stock Compensation. These provisions require that the estimated fair value of restricted stock (“Restricted Stock Awards”), performance share units, long term incentive plan awards and stock options at the grant date be amortized ratably into expense over the appropriate vesting period. The Company recorded stock compensation expense of $ 7,447,000 , $ 5,646,000 and $ 2,219,000 for the years ended December 31, 2017 , 2016 and 2015 , respectively. 
Other Comprehensive Income (Loss)	Other Comprehensive Income (Loss) Other comprehensive income (loss) includes items that are recorded in equity, such as effective portions of derivatives designated as cash flow hedges or unrealized holding gains or losses on marketable securities available for sale.
Fair Value Hierarchy	Fair Value Hierarchy The standard Fair Value Measurements specifies a hierarchy of valuation techniques based upon whether the inputs to those valuation techniques reflect assumptions other market participants would use based upon market data obtained from independent sources (observable inputs). The following summarizes the fair value hierarchy:  · Level 1: Quoted prices in active markets that are unadjusted and accessible at the measurement date for identical, unrestricted assets or liabilities; · Level 2: Quoted prices for identical assets and liabilities in markets that are inactive, quoted prices for similar assets and liabilities in active markets or financial instruments for which significant inputs are observable, either directly or indirectly, such as interest rates and yield curves that are observable at commonly quoted intervals and · Level 3: Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable.  In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, the level in the fair value hierarchy within which the fair value measurement in its entirety falls has been determined based on the lowest level input that is significant to the fair value measurement in its entirety. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment and considers factors specific to the asset or liability.
Impact Of Recently-Issued Accounting Standards	Impact Of Recently-Issued Accounting Standards In May 2014, the FASB issued Accounting Standards Update (“ASU”) 2014-09 Revenue from Contracts with Customers (Topic 606) ("ASU 2014-09"). ASU 2014-09 is a comprehensive new revenue recognition model requiring a company to recognize revenue to depict the transfer of goods or services to a customer at an amount reflecting the consideration it expects to receive in exchange for those goods or services. In adopting ASU 2014-09, companies may use either a full retrospective or a modified retrospective approach. Additionally, this guidance requires improved disclosures regarding the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. ASU 2014-09 is effective for the first interim period within annual reporting periods beginning after December 15, 2017, and early adoption is permitted for periods beginning after December 15, 2016. While lease contracts with customers, which constitute the majority of the Company’s revenues, are a specific scope exception of ASU 2014-09, certain of the Company’s revenue streams , including management services and other fee income, may be impacted by ASU 2014-09. The Company ha s evaluate d the effect the adoption will have on the Company’s revenue , and does not expect it will have a material impact on the Company’s consolidated financial statements, and also does not believe the adoption will significantly affect the timing of the recognition of the Company’s services income. The Company plans to adopt this standard using the modified retrospective approach, which requires a cumulative effect adjustment as of the date of adoption.  In February 2016, the FASB issued ASU 2016-02, modifying the principles for the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e. lessees and lessors). The new standard requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase by the lessee. This classification will determine whether lease expense is recognized based on an effective interest method or on a straight line basis over the term of the lease, respectively. A lessee is also required to record a right-of-use asset and a lease liability for all leases with a term of greater than 12 months regardless of their classification. Leases with a term of 12 months or less will be accounted for in the same manner as operating leases today. The new standard requires lessors to account for leases using an approach that is substantially equivalent to existing guidance for sales-type leases, direct financing leases and operating leases. The guidance is expected to impact the consolidated financial statements as the Company has certain operating and land lease arrangements for which it is the lessee. The guidance supersedes previously issued guidance under ASC Topic 840 “Leases.” The guidance is effective on January 1, 2019, with early adoption permitted. The Company is currently in the process of evaluating the impact the adoption of ASU 2016-02 will have on the Company’s consolidated financial statements.  In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments. ASU 2016-15 addresses eight specific cash flow issues and intends to reduce the diversity in practice in how certain cash receipts and cash payments are presented and classified in the statement of cash flows. This guidance is effective for annual periods beginning after December 15, 2017, including interim periods within that reporting period. Early adoption is permitted. Upon its adoption of ASU 2016-15, the Company will present its restricted cash with cash and not as a cash adjustment in the Company’s consolidated statement of cash flows.
Mack-Cali Realty LP [Member]
Significant Accounting Policies [Line Items]
Rental Property	Rental Property Rental properties are stated at cost less accumulated depreciation and amortization. Costs directly related to the acquisition, development and construction of rental properties are capitalized. Acquisition–related costs were expensed as incurred through December 31, 2016. The Company early adopted the recently issued FASB guidance Accounting Standards Update (“ASU”) 2017-01 on January 1, 2017 which revises the definition of a business and is expected to result in more transactions to be accounted for as asset acquisitions and significantly limit transactions that would be accounted for as business combinations. Where an acquisition has been determined to be an asset acquisition, acquisition-related costs are capitalized. Capitalized development and construction costs include pre-construction costs essential to the development of the property, development and construction costs, interest, property taxes, insurance, salaries and other project costs incurred during the period of development. Capitalized development and construction salaries and related costs approximated $ 2.2 million, $ 2.6 million and $4.2 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. Included in total rental property is construction, tenant improvement and development in-progress of $ 559.5 million and $ 361.1 million as of December 31, 2017 and 2016 , respectively. Ordinary repairs and maintenance are expensed as incurred; major replacements and betterments, which improve or extend the life of the asset, are capitalized and depreciated over their estimated useful lives. Fully-depreciated assets are removed from the accounts.  The Company considers a construction project as substantially completed and held available for occupancy upon the substantial completion of tenant improvements, but no later than one year from cessation of major construction activity (as distinguished from activities such as routine maintenance and cleanup). If portions of a rental project are substantially completed and occupied by tenants, or held available for occupancy, and other portions have not yet reached that stage, the substantially completed portions are accounted for as a separate project. The Company allocates costs incurred between the portions under construction and the portions substantially completed and held available for occupancy, primarily based on a percentage of the relative square footage of each portion, and capitalizes only those costs associated with the portion under construction.  Properties are depreciated using the straight-line method over the estimated useful lives of the assets. The estimated useful lives are as follows:   Leasehold interests Remaining lease term Buildings and improvements 5 to 40 years Tenant improvements The shorter of the term of the  related lease or useful life Furniture, fixtures and equipment 5 to 10 years  Upon acquisition of rental property, the Company estimates the fair value of acquired tangible assets, consisting of land, building and improvements, and identified intangible assets and liabilities assumed, generally consisting of the fair value of (i) above and below market leases, (ii) in-place leases and (iii) tenant relationships. The Company allocates the purchase price to the assets acquired and liabilities assumed based on their fair values. The Company records goodwill or a gain on bargain purchase (if any) if the net assets acquired/liabilities assumed differ from the purchase consideration of a business transaction.  In estimating the fair value of the tangible and intangible assets acquired, the Company considers information obtained about each property as a result of its due diligence and marketing and leasing activities, and utilizes various valuation methods, such as estimated cash flow projections utilizing appropriate discount and capitalization rates, estimates of replacement costs net of depreciation, and available market information. The fair value of the tangible assets of an acquired property considers the value of the property as if it were vacant.  Above-market and below-market lease values for acquired properties are initially recorded based on the present value (using a discount rate which reflects the risks associated with the leases acquired) of the difference between (i) the contractual amounts to be paid pursuant to each in-place lease and (ii) management’s estimate of fair market lease rates for each corresponding in-place lease, measured over a period equal to the remaining term of the lease for above-market leases and the remaining initial term plus the term of any below-market fixed rate renewal options for below-market leases. The capitalized above-market lease values are amortized as a reduction of base rental revenue over the remaining terms of the respective leases, and the capitalized below-market lease values are amortized as an increase to base rental revenue over the remaining initial terms plus the terms of any below-market fixed rate renewal options of the respective leases.  Other intangible assets acquired include amounts for in-place lease values and tenant relationship values, which are based on management’s evaluation of the specific characteristics of each tenant’s lease and the Company’s overall relationship with the respective tenant. Factors to be considered by management in its analysis of in-place lease values include an estimate of carrying costs during hypothetical expected lease-up periods considering current market conditions, and costs to execute similar leases. In estimating carrying costs, management includes real estate taxes, insurance and other operating expenses and estimates of lost rentals at market rates during the expected lease-up periods, depending on local market conditions. In estimating costs to execute similar leases, management considers leasing commissions, legal and other related expenses. Characteristics considered by management in valuing tenant relationships include the nature and extent of the Company’s existing business relationships with the tenant, growth prospects for developing new business with the tenant, the tenant’s credit quality and expectations of lease renewals. The value of in-place leases are amortized to expense over the remaining initial terms of the respective leases. The value of tenant relationship intangibles are amortized to expense over the anticipated life of the relationships.  On a periodic basis, management assesses whether there are any indicators that the value of the Company’s rental properties held for use may be impaired. In addition to identifying any specific circumstances which may affect a property or properties, management considers other criteria for determining which properties may require assessment for potential impairment. The criteria considered by management include reviewing low leased percentages, significant near-term lease expirations, current and historical operating and/or cash flow losses, near-term mortgage debt maturities and/or other factors, including those that might impact the Company’s intent and ability to hold the property. A property’s value is impaired only if management’s estimate of the aggregate future cash flows (undiscounted and without interest charges) to be generated by the property is less than the carrying value of the property. To the extent impairment has occurred, the impairment loss shall be measured as the excess of the carrying value of the property over the fair value of the property. The Company’s estimates of aggregate future cash flows expected to be generated by each property are based on a number of assumptions. These assumptions are generally based on management’s experience in its local real estate markets and the effects of current market conditions. The assumptions are subject to economic and market uncertainties including, among others, demand for space, competition for tenants, changes in market rental rates, and costs to operate each property. As these factors are difficult to predict and are subject to future events that may alter management’s assumptions, the future cash flows estimated by management in its impairment analyses may not be achieved, and actual losses or impairments may be realized in the future. 
Rental Property Held For Sale	Rental Property Held for Sale When assets are identified by management as held for sale, the Company discontinues depreciating the assets and estimates the sales price, net of selling costs, of such assets. The Company generally considers assets to be held for sale when the transaction has received appropriate corporate authority, and there are no significant contingencies relating to the sale. If, in management’s opinion, the estimated net sales price, net of selling costs, of the assets which have been identified as held for sale is less than the carrying value of the assets, a valuation allowance (which is recorded as unrealized losses on disposition of rental property) is established. If circumstances arise that previously were considered unlikely and, as a result, the Company decides not to sell a property previously classified as held for sale, the property is reclassified as held and used. A property that is reclassified is measured and recorded individually at the lower of (a) its carrying value before the property was classified as held for sale, adjusted for any depreciation (amortization) expense that would have been recognized had the property been continuously classified as held and used, or (b) the fair value at the date of the subsequent decision not to sell. 
Investments In Unconsolidated Joint Ventures	Investments in Unconsolidated Joint Ventures The Company accounts for its investments in unconsolidated joint ventures under the equity method of accounting. The Company applies the equity method by initially recording these investments at cost, as Investments in Unconsolidated Joint Ventures, subsequently adjusted for equity in earnings and cash contributions and distributions. The outside basis portion of the Company’s joint ventures is amortized over the anticipated useful lives of the underlying ventures’ tangible and intangible assets acquired and liabilities assumed. Generally, the Company would discontinue applying the equity method when the investment (and any advances) is reduced to zero and would not provide for additional losses unless the Company has guaranteed obligations of the venture or is otherwise committed to providing further financial support for the investee. If the venture subsequently generates income, the Company only recognizes its share of such income to the extent it exceeds its share of previously unrecognized losses.  If the venture subsequently makes distributions and the Company does not have an implied or actual commitment to support the operations of the venture, including a general partner interest in the investee, the Company will not record a basis less than zero, rather such amounts will be recorded as equity in earnings of unconsolidated joint ventures. On a periodic basis, management assesses whether there are any indicators that the value of the Company’s investments in unconsolidated joint ventures may be impaired. An investment is impaired only if management’s estimate of the value of the investment is less than the carrying value of the investment, and such decline in value is deemed to be other than temporary. To the extent impairment has occurred, the loss shall be measured as the excess of the carrying value of the investment over the value of the investment. The Company’s estimates of value for each investment (particularly in real estate joint ventures) are based on a number of assumptions that are subject to economic and market uncertainties including, among others, demand for space, competition for tenants, changes in market rental rates, and operating costs. As these factors are difficult to predict and are subject to future events that may alter management’s assumptions, the values estimated by management in its impairment analyses may not be realized, and actual losses or impairment may be realized in the future. See Note 4: Investments in Unconsolidated Joint Ventures.
Cash And Cash Equivalents	Cash and Cash Equivalents All highly liquid investments with an original maturity of three months or less when purchased are considered to be cash equivalents.
Deferred Financing Costs	 Deferred Financing Costs Costs incurred in obtaining financing are capitalized and amortized over the term of the related indebtedness. Deferred financing costs are presented in the balance sheet as a direct deduction from the carrying value of the debt liability to which they relate, except deferred financing costs related to the revolving credit facility, which are presented in deferred charges, goodwill and other assets. In all cases, amortization of such costs is included in interest expense and was $ 4,612,000 , $ 4,582,000 and $ 3,790,000 for the years ended December 31, 2017 , 2016 and 2015 , respectively. If a financing obligation is extinguished early, any unamortized deferred financing costs are written off and included in gains (losses) from extinguishment of debt. Included in loss from extinguishment of debt, net of gains, of $0.4 million, $30.5 million and zero for the years ended December 31, 2017 , 2016 and 2015 were unamortized deferred financing costs which were written off amounting to $0.4 million, $ 0.7 million and zero , respectively.
Deferred Leasing Costs	Deferred Leasing Costs Costs incurred in connection with successfully executed commercial leases are capitalized and amortized on a straight-line basis over the terms of the related leases and included in depreciation and amortization. Unamortized deferred leasing costs are charged to amortization expense upon early termination of the lease. Certain employees of the Company are compensated for providing leasing services to the Properties. The portion of such compensation related to commercial leases, which is capitalized and amortized, and included in deferred charges, goodwill and other assets, net was approximately $ 3,146,000 , $ 3,270,000 and $ 3,521,000 for the years ended December 31, 2017 , 2016 and 2015 , respectively.
Goodwill	Goodwill Goodwill represents the excess of the purchase price over the fair value of net tangible and intangible assets acquired in a business combination. Goodwill is allocated to various reporting units, as applicable. Each of the Company’s segments consists of a reporting unit. Goodwill is not amortized. Management performs an annual impairment test for goodwill during the fourth quarter and between annual tests, management evaluates the recoverability of goodwill whenever events or changes in circumstances indicate that the carrying value of goodwill may not be fully recoverable. In its impairment tests of goodwill, management first assesses qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying value. If based on this assessment, management determines that the fair value of the reporting unit is not less than its carrying value, then performing the additional two-step impairment test is unnecessary. If the carrying value of goodwill exceeds its fair value, an impairment charge is recognized. The Company determined that its goodwill was not impaired at December 31, 2017 after management performed its impairment tests.
Derivative Instruments	Derivative Instruments The Company measures derivative instruments, including certain derivative instruments embedded in other contracts, at fair value and records them as an asset or liability, depending on the Company’s rights or obligations under the applicable derivative contract. For derivatives designated and qualifying as fair value hedges, the changes in the fair value of both the derivative instrument and the hedged item are recorded in earnings. For derivatives designated as cash flow hedges, the effective portions of the derivative are reported in other comprehensive income (“OCI”) and are subsequently reclassified into earnings when the hedged item affects earnings. Changes in fair value of derivative instruments not designated as hedging and ineffective portions of hedges are recognized in earnings in the affected period.
Revenue Recognition	Revenue Recognition Base rental revenue is recognized on a straight-line basis over the terms of the respective leases. Unbilled rents receivable represents the cumulative amount by which straight-line rental revenue exceeds rents currently billed in accordance with the lease agreements.  Above-market and below-market lease values for acquired properties are initially recorded based on the present value (using a discount rate which reflects the risks associated with the leases acquired) of the difference between (i) the contractual amounts to be paid pursuant to each in-place lease and (ii) management’s estimate of fair market lease rates for each corresponding in-place lease, measured over a period equal to the remaining term of the lease for above-market leases and the remaining initial term plus the term of any below-market fixed-rate renewal options for below-market leases. The capitalized above-market lease values for acquired properties are amortized as a reduction of base rental revenue over the remaining terms of the respective leases, and the capitalized below-market lease values are amortized as an increase to base rental revenue over the remaining initial terms plus the terms of any below-market fixed-rate renewal options of the respective leases.  Escalations and recoveries from tenants are received from tenants for certain costs as provided in the lease agreements. These costs generally include real estate taxes, utilities, insurance, common area maintenance and other recoverable costs. See Note 13: Tenant Leases.  Real estate services revenue includes property management, development, construction and leasing commission fees and other services, and payroll and related costs reimbursed from clients. Fee income derived from the Company’s unconsolidated joint ventures (which are capitalized by such ventures) are recognized to the extent attributable to the unaffiliated ownership interests.  Parking income includes income from parking spaces leased to tenants and others.  Other income includes income from tenants for additional services arranged for by the Company and income from tenants for early lease terminations.   
Allowance For Doubtful Accounts	Allowance for Doubtful Accounts Management performs a detailed review of amounts due from tenants to determine if an allowance for doubtful accounts is required based on factors affecting the collectability of the accounts receivable balances. The factors considered by management in determining which individual tenant receivable balances, or aggregate receivable balances, require a collectability allowance include the age of the receivable, the tenant’s payment history, the nature of the charges, any communications regarding the charges and other related information. Management’s estimate of the allowance for doubtful accounts requires management to exercise significant judgment about the timing, frequency and severity of collection losses, which affects the allowance and net income.
Income And Other Taxes	Income and Other Taxes The General Partner has elected to be taxed as a REIT under Sections 856 through 860 of the Internal Revenue Code of 1986, as amended (the “IRS Code”). As a REIT, the General Partner generally will not be subject to corporate federal income tax on net income that it currently distributes to its shareholders, provided that the General Partner satisfies certain organizational and operational requirements including the requirement to distribute at least 90 percent of its REIT taxable income (determined by excluding any net capital gains) to its shareholders. If and to the extent the General Partner retains and does not distribute any net capital gains, the General Partner will be required to pay federal, state and local taxes, as applicable, on such net capital gains at the rate applicable to capital gains of a corporation.  The Operating Partnership is a partnership, and, as a result, all income and losses of the partnership are allocated to the partners for inclusion in their respective tax returns. Accordingly, no provision or benefit for income taxes has been made in the accompanying financial statements.  As of December 31, 2017 , the estimated net basis of the rental property for federal income tax purposes was lower than the net assets as reported in the Operating Partnership’s financial statements by approximately $231,067,000 . The Operating Partnership’s taxable income for the year ended December 31, 2017 was estimated to be approximately $97,037,000 and for the years ended December 31, 2016 and 2015 was approximately $30,208,000 and $63,285,000 , respectively. The differences between book income and taxable income primarily result from differences in depreciation expenses, the recording of rental income, differences in the deductibility of certain expenses for tax purposes, differences in revenue recognition and the rules for tax purposes of a property exchange.  The General Partner has elected to treat certain of its corporate subsidiaries as taxable REIT subsidiaries (each a “TRS”). In general, a TRS of the General Partner may perform additional services for tenants of the Company and generally may engage in any real estate or non-real estate related business (except for the operation or management of health care facilities or lodging facilities or the providing to any person, under a franchise, license or otherwise, rights to any brand name under which any lodging facility or health care facility is operated). A TRS is subject to corporate federal income tax. The General Partner has conducted business through its TRS entities for certain property management, development, construction and other related services, as well as to hold a joint venture interest in a hotel and other matters.  The deferred tax balance at December 31, 2017 is $ 11.7 million which has been fully reserved through a valuation allowance. New tax reform legislation enacted in late 2017 reduces the corporate tax rate to 21 percent, effective January 1, 2018. Consequently, the Company’s deferred tax assets were re-measured to reflect the reduction in the future U.S. corporate income tax rate as of the enactment date . As a result, the Company recorded a decrease related to deferred tax assets of $5.3 million and a decrease to the associated valuation allowance of $5.3 million at December 31, 2017. If the General Partner fails to qualify as a REIT in any taxable year, the Company will be subject to federal income tax on its taxable income at regular corporate tax rates. The Company is subject to certain state and local taxes.  Pursuant to the amended provisions related to uncertain tax provisions of ASC 740, Income Taxes, the Company recognized no material adjustments regarding its tax accounting treatment. The Company expects to recognize interest and penalties related to uncertain tax positions, if any, as income tax expense, which is included in general and administrative expense.  In the normal course of business, the Company or one of its subsidiaries is subject to examination by federal, state and local jurisdictions in which it operates, where applicable. As of December 31, 2017 , the tax years that remain subject to examination by the major tax jurisdictions under the statute of limitations are generally from the year 2013 forward. 
Earnings Per Share Or Unit	Earnings Per Share or Unit The Company presents both basic and diluted earnings per share or unit (“EPS or EPU”). Basic EPS or EPU excludes dilution and is computed by dividing net income available to common shareholders or unitholders by the weighted average number of shares or units outstanding for the period. Diluted EPS or EPU reflects the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock, where such exercise or conversion would result in a lower EPS or EPU from continuing operations amount. Shares or Units whose issuance is contingent upon the satisfaction of certain conditions shall be considered outstanding and included in the computation of diluted EPS or EPU as follows (i) if all necessary conditions have been satisfied by the end of the period (the events have occurred), those shares or units shall be included as of the beginning of the period in which the conditions were satisfied (or as of the date of the grant, if later) or (ii) if all necessary conditions have not been satisfied by the end of the period, the number of contingently issuable shares or units included in diluted EPS or EPU shall be based on the number of shares or units, if any, that would be issuable if the end of the reporting period were the end of the contingency period (for example, the number of shares or units that would be issuable based on current period earnings or period-end market price) and if the result would be dilutive. Those contingently issuable shares or units shall be included in the denominator of diluted EPS or EPU as of the beginning of the period (or as of the date of the grant, if later). 
Dividends And Distributions Payable	Dividends and Distributions Payable The dividends and distributions payable at December 31, 2017 represents dividends payable to common shareholders ( 89,914,658 shares) and distributions payable to noncontrolling interest unitholders of the Operating Partnership ( 10,438,855 common units and 1,230,877 LTIP units) for all such holders of record as of January 3, 2018 with respect to the fourth quarter 2017 . The fourth quarter 2017 common stock dividends and unit distributions of $ 0.20 per common share, common unit and LTIP unit were approved by the General Partner’s Board of Directors on December 12, 2017 and paid on January 12, 2018 .  The dividends and distributions payable at December 31, 2016 represents dividends payable to common shareholders ( 89,696,824 shares) and distributions payable to noncontrolling interest unitholders of the Operating Partnership ( 10,488,105 common units and 657,373 LTIP units) for all such holders of record as of January 5, 2017 with respect to the fourth quarter 2016 . The fourth quarter 2016 common stock dividends and unit distributions of $ 0.15 per common share, common unit and LTIP unit were approved by the General Partner’s Board of Directors on December 13, 2016 and paid on January 13, 2017 .  The Company has determined that the $ 0.70 dividend per common share paid during the year ended December 31, 2017 represented 100 percent ordinary income; the $ 0.60 dividend per common share paid during the year ended December 31, 2016 represented 100 percent return of capital; and the $ 0.60 dividend per common share paid during the year ended December 31, 2015 represented approximately 90 percent ordinary income and approximately 10 percent return of capital. 
Costs Incurred For Stock Issuances	Costs Incurred For Stock Issuances Costs incurred in connection with the Company’s stock issuances are reflected as a reduction of additional paid ‑in capital. 
Stock Compensation	Stock Compensation The Company accounts for stock compensation in accordance with the provisions of ASC 718, Compensation-Stock Compensation. These provisions require that the estimated fair value of restricted stock (“Restricted Stock Awards”), performance share units, long term incentive plan awards and stock options at the grant date be amortized ratably into expense over the appropriate vesting period. The Company recorded stock compensation expense of $ 7,447,000 , $ 5,646,000 and $ 2,219,000 for the years ended December 31, 2017 , 2016 and 2015 , respectively. 
Other Comprehensive Income (Loss)	Other Comprehensive Income (Loss) Other comprehensive income (loss) includes items that are recorded in equity, such as effective portions of derivatives designated as cash flow hedges or unrealized holding gains or losses on marketable securities available for sale.
Fair Value Hierarchy	Fair Value Hierarchy The standard Fair Value Measurements specifies a hierarchy of valuation techniques based upon whether the inputs to those valuation techniques reflect assumptions other market participants would use based upon market data obtained from independent sources (observable inputs). The following summarizes the fair value hierarchy:  · Level 1: Quoted prices in active markets that are unadjusted and accessible at the measurement date for identical, unrestricted assets or liabilities; · Level 2: Quoted prices for identical assets and liabilities in markets that are inactive, quoted prices for similar assets and liabilities in active markets or financial instruments for which significant inputs are observable, either directly or indirectly, such as interest rates and yield curves that are observable at commonly quoted intervals and · Level 3: Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable.  In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, the level in the fair value hierarchy within which the fair value measurement in its entirety falls has been determined based on the lowest level input that is significant to the fair value measurement in its entirety. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment and considers factors specific to the asset or liability.
Impact Of Recently-Issued Accounting Standards	Impact Of Recently-Issued Accounting Standards In May 2014, the FASB issued Accounting Standards Update (“ASU”) 2014-09 Revenue from Contracts with Customers (Topic 606) ("ASU 2014-09"). ASU 2014-09 is a comprehensive new revenue recognition model requiring a company to recognize revenue to depict the transfer of goods or services to a customer at an amount reflecting the consideration it expects to receive in exchange for those goods or services. In adopting ASU 2014-09, companies may use either a full retrospective or a modified retrospective approach. Additionally, this guidance requires improved disclosures regarding the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. ASU 2014-09 is effective for the first interim period within annual reporting periods beginning after December 15, 2017, and early adoption is permitted for periods beginning after December 15, 2016. While lease contracts with customers, which constitute the majority of the Company’s revenues, are a specific scope exception of ASU 2014-09, certain of the Company’s revenue streams , including management services and other fee income, may be impacted by ASU 2014-09. The Company ha s evaluate d the effect the adoption will have on the Company’s revenue , and does not expect it will have a material impact on the Company’s consolidated financial statements, and also does not believe the adoption will significantly affect the timing of the recognition of the Company’s services income. The Company plans to adopt this standard using the modified retrospective approach, which requires a cumulative effect adjustment as of the date of adoption.  In February 2016, the FASB issued ASU 2016-02, modifying the principles for the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e. lessees and lessors). The new standard requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase by the lessee. This classification will determine whether lease expense is recognized based on an effective interest method or on a straight line basis over the term of the lease, respectively. A lessee is also required to record a right-of-use asset and a lease liability for all leases with a term of greater than 12 months regardless of their classification. Leases with a term of 12 months or less will be accounted for in the same manner as operating leases today. The new standard requires lessors to account for leases using an approach that is substantially equivalent to existing guidance for sales-type leases, direct financing leases and operating leases. The guidance is expected to impact the consolidated financial statements as the Company has certain operating and land lease arrangements for which it is the lessee. The guidance supersedes previously issued guidance under ASC Topic 840 “Leases.” The guidance is effective on January 1, 2019, with early adoption permitted. The Company is currently in the process of evaluating the impact the adoption of ASU 2016-02 will have on the Company’s consolidated financial statements.  In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments. ASU 2016-15 addresses eight specific cash flow issues and intends to reduce the diversity in practice in how certain cash receipts and cash payments are presented and classified in the statement of cash flows. This guidance is effective for annual periods beginning after December 15, 2017, including interim periods within that reporting period. Early adoption is permitted. Upon its adoption of ASU 2016-15, the Company will present its restricted cash with cash and not as a cash adjustment in the Company’s consolidated statement of cash flows.

Significant Accounting Polici30

Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2017
Significant Accounting Policies [Line Items]
Estimated Useful Lives Of Assets	 Leasehold interests Remaining lease term Buildings and improvements 5 to 40 years Tenant improvements The shorter of the term of the  related lease or useful life Furniture, fixtures and equipment 5 to 10 years 
Mack-Cali Realty LP [Member]
Significant Accounting Policies [Line Items]
Estimated Useful Lives Of Assets	 Leasehold interests Remaining lease term Buildings and improvements 5 to 40 years Tenant improvements The shorter of the term of the  related lease or useful life Furniture, fixtures and equipment 5 to 10 years 

Recent Transactions (Tables)

Recent Transactions (Tables)	12 Months Ended
	Dec. 31, 2017
Real Estate Properties [Line Items]
Schedule Of Properties Acquired	 2017 The Company acquired the following office properties (which were determined to be asset acquisitions in accordance with ASU 2017-01) during the year ended December 31, 2017 (dollars in thousands) :   Acquisition # of Rentable Acquisition Date Property Address Location Bldgs. Square Feet Cost 01/11/17 Red Bank portfolio (a) Red Bank, New Jersey 3 279,472 $ 27,228 03/06/17 Short Hills/Madison portfolio (b) Short Hills & Madison, New Jersey 6 1,113,028 367,361  Total Acquisitions 9 1,392,500 $ 394,589  (a) This acquisition was funded through borrowings under the Company's unsecured revolving credit facility. (b) This acquisition was funded through borrowings under the Company’s unsecured revolving credit facility and a new $124.5 million loan secured by three of the properties.  2016 The Company acquired the following office properties during the year ended December 31, 2016 ( dollars in thousands) :    Acquisition # of Rentable Acquisition Date Property Address Location Bldgs. Square Feet Cost 04/04/16 11 Martine Avenue (a) White Plains, New York 1 82,000 $ 10,750 04/07/16 320, 321 University Avenue (b) Newark, New Jersey 2 147,406 23,000 06/02/16 101 Wood Avenue South (c) Edison, New Jersey 1 262,841 82,300 07/01/16 111 River Street (c) Hoboken, New Jersey 1 566,215 210,761  Total Acquisitions 5 1,058,462 $ 326,811  (a) Acquisition represented four units of condominium interests which collectively comprise floors 2 through 5. Upon completion of the acquisition, the Company owns the entire 14-story 262,000 square-foot building. The acquisition was funded using available cash. (b) This acquisition was funded through borrowings under the Company’s unsecured revolving credit facility. (c) This acquisition was funded using available cash and through borrowings under the Company’s unsecured revolving credit facility.  
Schedule Of Purchase Price Allocation	2017 The purchase prices were allocated to the net assets acquired, as follows (in thousands) :     Red Bank Short Hills/Madison  Portfolio Portfolio Total Land and leasehold interest $ 7,914 $ 30,336 $ 38,250 Buildings and improvements and other assets 16,047 295,299 311,346 Above market leases (a) 118 6,367 6,485 In-place lease values (a) 3,171 45,604 48,775  27,250 377,606 404,856 Less: Below market lease values (a) (22) (10,245) (10,267) Net assets recorded upon acquisition $ 27,228 $ 367,361 $ 394,589  (a) Above market, in-place and below market leases are being amortized over a weighted-average term of 5.4 years.  2016 The purchase prices were allocated to the net assets acquired, as follows (in thousands) :    320,321  11 Martine University 101 Wood 111 River  Avenue Avenue Avenue Street Land and leasehold interest $ 2,460 $ 7,305 $ 8,509 $ 204 Buildings and improvements 8,290 15,695 72,738 198,609 Above market leases (a) - - 58 617 In-place lease values (a) - - 6,743 43,801 Other assets - - - 11,279  88,048 254,510 Less: Below market lease values (a) - - (5,748) (43,749) Net assets recorded upon acquisition $ 10,750 $ 23,000 $ 82,300 $ 210,761  (a) Above market, in-place and below market leases are being amortized over a weighted-average term of 8.1 years.  
Schedule Of Properties Which Commenced Initial Operations	   Total  In-Service # of Development  Date Property Location Type Apartment Units Costs  12/01/16 Quarry Place at Tuckahoe Eastchester, NY Multi-Family 108 $ 56,961 (a)  12/01/16 The Chase II at Overlook Ridge Malden, MA Multi-Family 292 65,218 (b)  Totals 400 $ 122,179  (a) Development costs as of December 31, 2016 included approximately $5.6 million in land costs. (b) Development costs as of December 31, 2016 included approximately $10.8 million in land costs. As of December 31, 2016, the Company anticipates additional costs of approximately $9.7 million, which will be funded from a construction loan.
Schedule Of Net Assets Recorded Upon Consolidation	2017    Monaco Monaco  North South Total Land and leasehold interest $ 27,300 $ 31,461 $ 58,761 Buildings and improvements and other assets 112,841 129,895 242,736 Above market leases (a) 350 - 350 In-place lease values (a) 4,585 4,913 9,498 Less: Below market lease values (a) (141) (118) (259)  144,935 166,151 311,086 Less: Debt assumed at fair value (79,544) (91,656) (171,200) Net assets recorded upon consolidation $ 65,391 $ 74,495 $ 139,886  (a) Above market, in-place and below market leases are being amortized over a weighted-average term of 8 months.  2016    Overlook Portside  Ridge Apts Land and leasehold interest $ 11,072 $ - Buildings and improvements 87,793 73,713 Furniture, fixtures and equipment 1,695 1,038 Other assets 237 10,181 In-place lease values (a) 4,389 2,637 Less: Below market lease values (a) (489) (242) Sub Total 104,697 87,327  Less: Debt assumed (52,662) (42,500)  Net assets recorded upon consolidation $ 52,035 $ 44,827  (a) In-place lease values and below-market lease values are being amortized over a weighted average term of 7.4 months. 
Schedule Of Dispositions/Rental Property Held For Sale	Disposition/rental property held for sale  2017 The Company disposed of the following office properties during the year ended December 31, 2017 (dollars in thousands) :     Realized  Gains  Rentable Net Net (losses)/ Disposition # of Square Sales Carrying Unrealized Date Property/Address Location Bldgs. Feet Proceeds Value Losses, net 01/30/17 Cranford portfolio Cranford, New Jersey 6 435,976 $ 26,598 $ 22,736 $ 3,862 01/31/17 440 Route 22 East (a) Bridgewater, New Jersey 1 198,376 10,074 10,069 5 02/07/17 3 Independence Way Princeton, New Jersey 1 111,300 11,549 9,910 1,639 05/15/17 103 Carnegie Center Princeton, New Jersey 1 96,000 15,063 8,271 6,792 08/29/17 400 Chestnut Ridge Road Woodcliff Lake, New Jersey 1 89,200 6,891 7,498 (607) 08/30/17 140 E. Ridgewood Avenue Paramus, New Jersey 1 239,680 30,201 30,737 (536) 08/30/17 Bergen portfolio Woodcliff Lake, Paramus and 5 1,061,544 86,973 (c) 135,121 (48,148)  Rochelle Park, New Jersey 09/11/17 377 Summerhill Road East Brunswick, New Jersey 1 40,000 3,221 2,172 1,049 09/13/17 700 Executive Boulevard Elmsford, New York - - (b) 5,717 970 4,747 09/20/17 Totowa Portfolio Totowa, New Jersey 13 499,243 63,624 27,630 35,994 09/27/17 890 Mountain Avenue (d) New Providence, New Jersey 1 80,000 4,852 6,139 (1,287) 09/28/17 135 Chestnut Ridge Road Montvale, New Jersey 1 66,150 5,844 (e) 2,929 2,915 09/29/17 Moorestown portfolio Moorestown and Burlington, New Jersey 26 1,260,398 73,393 (f) 56,186 17,207 10/19/17 1 Enterprise Boulevard Yonkers, New York - - (b) 3,230 1,380 1,850 11/15/17 61 South Paramus Road Paramus, New Jersey 1 269,191 23,255 37,184 (13,929) 12/06/17 300 Tice Boulevard Woodcliff Lake, New Jersey 1 230,000 28,847 25,705 3,142 Sub-total 60 4,677,058 399,332 384,637 14,695  Unrealized losses on rental property held for sale (12,331)  Totals 60 4,677,058 $ 399,332 $ 384,637 $ 2,364  (a) The Company recorded a valuation allowance of $7.7 million on this property during the year ended December 31, 2016. (b) This disposition is of a ground leased land property. (c) At closing, the Company provided short term seller financing aggregating $65 million through mortgage notes receivable to the buyers. These notes were paid off in November and December 2017. (d) The Company recorded an impairment charge of $7.0 million on this property during the year ended December 31, 2015. (e) The Company recorded an impairment charge of $4.2 million on this property during the year ended December 31, 2015. $5.9 million of the sales proceeds from this sale were held by a qualified intermediary, which is noncash and recorded in deferred charges, goodwill and other assets as of December 31, 2017. See Note 5: Deferred Charges, Goodwill and Other Assets, Net. (f) $15.3 million of the sales proceeds from this sale were held by a qualified intermediary, which is noncash and recorded in deferred charges, goodwill and other assets as of December 31, 2017. See Note 5: Deferred Charges, Goodwill and Other Assets, Net.   2016 The Company disposed of the following office and multi-family properties during the year ended December 31, 2016 (dollars in thousands) :     Realized  Gains  Net Net (losses)/ Disposition # of Sales Carrying Unrealized Date Property/Address Location Bldgs. Proceeds Value Losses, net 03/11/16 2 Independence Way (a) Princeton, New Jersey 1 $ 4,119 $ 4,283 $ (164) 03/24/16 1201 Connecticut Avenue, NW Washington, D.C. 1 90,591 31,827 58,764 04/26/16 125 Broad Street (b) New York, New York 1 192,323 200,183 (7,860) 05/09/16 9200 Edmonston Road Greenbelt, Maryland 1 4,083 (c) 3,837 246 05/18/16 1400 L Street Washington, D.C. 1 68,399 30,053 38,346 07/14/16 600 Parsippany Road Parsippany, New Jersey 1 10,465 (d) 5,875 4,590 07/14/16 4,5,6 Century Drive (e) Parsippany, New Jersey 3 14,533 17,308 (2,775) 08/11/16 Andover Place Andover, Massachusetts 1 39,863 37,150 2,713 09/26/16 222,233 Mount Airy Road (f) Basking Ridge, New Jersey 2 8,817 9,039 (222) 09/27/16 10 Mountainview Road Upper Saddle River, New Jersey 1 18,990 19,571 (581) 11/07/16 100 Willowbrook, 2,3,4 Paragon (g) Freehold, New Jersey 4 14,634 19,377 (4,743) 12/05/16 4 Becker Farm Road Roseland, New Jersey 1 41,400 (h) 31,001 10,399 12/09/16 101,103,105 Eisenhower Parkway Roseland, New Jersey 3 46,423 45,999 424 12/22/16 Capital Office Park, Ivy Lane (i) Greenbelt, Maryland 6 46,570 65,064 (18,494) 12/22/16 100 Walnut Avenue Clark, New Jersey 1 28,428 7,529 20,899 12/22/16 20 Commerce Drive Cranford, New Jersey 1 28,878 13,071 15,807 12/29/16 4200 Parliament Place (j) Lanham, Maryland 1 5,965 5,983 (18) Sub-total 30 664,481 547,150 117,331  Unrealized losses on rental property held for sale (7,665)  Totals 30 $ 664,481 $ 547,150 $ 109,666  (a) The Company recorded an impairment charge of $3.2 million on this property during the year ended December 31, 2015. (b) The Company recorded impairment charges of $83.2 million on this property during the year ended December 31, 2015. (c) The Company transferred the deed for this property to the lender in satisfaction of its obligations. The Company recorded an impairment charge of $3.0 million on this property during the year ended December 31, 2012. (d) $10.5 million of the net sales proceeds from this sale were held by a qualified intermediary. The Company received these proceeds on January 11, 2017. (e) The Company recorded impairment charges of $9.8 million on these properties during the year ended December 31, 2015. (f) The Company recorded impairment charges of $1.0 million on these properties during the year ended December 31, 2015. (g) The Company recorded impairment charges of $7.4 million on these properties during the year ended December 31, 2015. (h) The Company transferred the deed for this property to the lender in satisfaction of its obligations. (i) The Company recorded impairment charges of $66.5 million on these properties during the year ended December 31, 2015. (j) The Company recorded an impairment charge of $4.2 million on this property during the year ended December 31, 2015. 
Disposal Group, Held-for-sale, Not Discontinued Operations [Member]
Real Estate Properties [Line Items]
Summary Of Income From Property Held For Sale, Net	The following table summarizes the rental property held for sale, net, as of December 31, 2017: (dollars in thousands)     December 31,  2017 Land $ 37,024 Buildings and improvements 273,388 Less: Accumulated depreciation (126,503) Less: Unrealized losses on properties held for sale (12,331) Rental property held for sale,net $ 171,578   The following table summarizes the rental property held for sale, net, as of December 31, 2016: (dollars in thousands)     December 31,  2016 Land $ 10,934 Buildings and improvements 68,266 Less: Accumulated depreciation (31,792) Less: Unrealized losses on properties held for sale (7,665) Rental property held for sale,net $ 39,743 
Mack-Cali Realty LP [Member]
Real Estate Properties [Line Items]
Schedule Of Properties Acquired	 2017 The Company acquired the following office properties (which were determined to be asset acquisitions in accordance with ASU 2017-01) during the year ended December 31, 2017 (dollars in thousands) :   Acquisition # of Rentable Acquisition Date Property Address Location Bldgs. Square Feet Cost 01/11/17 Red Bank portfolio (a) Red Bank, New Jersey 3 279,472 $ 27,228 03/06/17 Short Hills/Madison portfolio (b) Short Hills & Madison, New Jersey 6 1,113,028 367,361  Total Acquisitions 9 1,392,500 $ 394,589  (a) This acquisition was funded through borrowings under the Company's unsecured revolving credit facility. (b) This acquisition was funded through borrowings under the Company’s unsecured revolving credit facility and a new $124.5 million loan secured by three of the properties.  2016 The Company acquired the following office properties during the year ended December 31, 2016 ( dollars in thousands) :    Acquisition # of Rentable Acquisition Date Property Address Location Bldgs. Square Feet Cost 04/04/16 11 Martine Avenue (a) White Plains, New York 1 82,000 $ 10,750 04/07/16 320, 321 University Avenue (b) Newark, New Jersey 2 147,406 23,000 06/02/16 101 Wood Avenue South (c) Edison, New Jersey 1 262,841 82,300 07/01/16 111 River Street (c) Hoboken, New Jersey 1 566,215 210,761  Total Acquisitions 5 1,058,462 $ 326,811  (a) Acquisition represented four units of condominium interests which collectively comprise floors 2 through 5. Upon completion of the acquisition, the Company owns the entire 14-story 262,000 square-foot building. The acquisition was funded using available cash. (b) This acquisition was funded through borrowings under the Company’s unsecured revolving credit facility. (c) This acquisition was funded using available cash and through borrowings under the Company’s unsecured revolving credit facility.  
Schedule Of Purchase Price Allocation	2017 The purchase prices were allocated to the net assets acquired, as follows (in thousands) :     Red Bank Short Hills/Madison  Portfolio Portfolio Total Land and leasehold interest $ 7,914 $ 30,336 $ 38,250 Buildings and improvements and other assets 16,047 295,299 311,346 Above market leases (a) 118 6,367 6,485 In-place lease values (a) 3,171 45,604 48,775  27,250 377,606 404,856 Less: Below market lease values (a) (22) (10,245) (10,267) Net assets recorded upon acquisition $ 27,228 $ 367,361 $ 394,589  (a) Above market, in-place and below market leases are being amortized over a weighted-average term of 5.4 years.  2016 The purchase prices were allocated to the net assets acquired, as follows (in thousands) :    320,321  11 Martine University 101 Wood 111 River  Avenue Avenue Avenue Street Land and leasehold interest $ 2,460 $ 7,305 $ 8,509 $ 204 Buildings and improvements 8,290 15,695 72,738 198,609 Above market leases (a) - - 58 617 In-place lease values (a) - - 6,743 43,801 Other assets - - - 11,279  88,048 254,510 Less: Below market lease values (a) - - (5,748) (43,749) Net assets recorded upon acquisition $ 10,750 $ 23,000 $ 82,300 $ 210,761  (a) Above market, in-place and below market leases are being amortized over a weighted-average term of 8.1 years.  
Schedule Of Properties Which Commenced Initial Operations	   Total  In-Service # of Development  Date Property Location Type Apartment Units Costs  12/01/16 Quarry Place at Tuckahoe Eastchester, NY Multi-Family 108 $ 56,961 (a)  12/01/16 The Chase II at Overlook Ridge Malden, MA Multi-Family 292 65,218 (b)  Totals 400 $ 122,179  (a) Development costs as of December 31, 2016 included approximately $5.6 million in land costs. (b) Development costs as of December 31, 2016 included approximately $10.8 million in land costs. As of December 31, 2016, the Company anticipates additional costs of approximately $9.7 million, which will be funded from a construction loan.
Schedule Of Net Assets Recorded Upon Consolidation	2017    Monaco Monaco  North South Total Land and leasehold interest $ 27,300 $ 31,461 $ 58,761 Buildings and improvements and other assets 112,841 129,895 242,736 Above market leases (a) 350 - 350 In-place lease values (a) 4,585 4,913 9,498 Less: Below market lease values (a) (141) (118) (259)  144,935 166,151 311,086 Less: Debt assumed at fair value (79,544) (91,656) (171,200) Net assets recorded upon consolidation $ 65,391 $ 74,495 $ 139,886  (a) Above market, in-place and below market leases are being amortized over a weighted-average term of 8 months.  2016    Overlook Portside  Ridge Apts Land and leasehold interest $ 11,072 $ - Buildings and improvements 87,793 73,713 Furniture, fixtures and equipment 1,695 1,038 Other assets 237 10,181 In-place lease values (a) 4,389 2,637 Less: Below market lease values (a) (489) (242) Sub Total 104,697 87,327  Less: Debt assumed (52,662) (42,500)  Net assets recorded upon consolidation $ 52,035 $ 44,827  (a) In-place lease values and below-market lease values are being amortized over a weighted average term of 7.4 months. 
Schedule Of Dispositions/Rental Property Held For Sale	Disposition/rental property held for sale  2017 The Company disposed of the following office properties during the year ended December 31, 2017 (dollars in thousands) :     Realized  Gains  Rentable Net Net (losses)/ Disposition # of Square Sales Carrying Unrealized Date Property/Address Location Bldgs. Feet Proceeds Value Losses, net 01/30/17 Cranford portfolio Cranford, New Jersey 6 435,976 $ 26,598 $ 22,736 $ 3,862 01/31/17 440 Route 22 East (a) Bridgewater, New Jersey 1 198,376 10,074 10,069 5 02/07/17 3 Independence Way Princeton, New Jersey 1 111,300 11,549 9,910 1,639 05/15/17 103 Carnegie Center Princeton, New Jersey 1 96,000 15,063 8,271 6,792 08/29/17 400 Chestnut Ridge Road Woodcliff Lake, New Jersey 1 89,200 6,891 7,498 (607) 08/30/17 140 E. Ridgewood Avenue Paramus, New Jersey 1 239,680 30,201 30,737 (536) 08/30/17 Bergen portfolio Woodcliff Lake, Paramus and 5 1,061,544 86,973 (c) 135,121 (48,148)  Rochelle Park, New Jersey 09/11/17 377 Summerhill Road East Brunswick, New Jersey 1 40,000 3,221 2,172 1,049 09/13/17 700 Executive Boulevard Elmsford, New York - - (b) 5,717 970 4,747 09/20/17 Totowa Portfolio Totowa, New Jersey 13 499,243 63,624 27,630 35,994 09/27/17 890 Mountain Avenue (d) New Providence, New Jersey 1 80,000 4,852 6,139 (1,287) 09/28/17 135 Chestnut Ridge Road Montvale, New Jersey 1 66,150 5,844 (e) 2,929 2,915 09/29/17 Moorestown portfolio Moorestown and Burlington, New Jersey 26 1,260,398 73,393 (f) 56,186 17,207 10/19/17 1 Enterprise Boulevard Yonkers, New York - - (b) 3,230 1,380 1,850 11/15/17 61 South Paramus Road Paramus, New Jersey 1 269,191 23,255 37,184 (13,929) 12/06/17 300 Tice Boulevard Woodcliff Lake, New Jersey 1 230,000 28,847 25,705 3,142 Sub-total 60 4,677,058 399,332 384,637 14,695  Unrealized losses on rental property held for sale (12,331)  Totals 60 4,677,058 $ 399,332 $ 384,637 $ 2,364  (a) The Company recorded a valuation allowance of $7.7 million on this property during the year ended December 31, 2016. (b) This disposition is of a ground leased land property. (c) At closing, the Company provided short term seller financing aggregating $65 million through mortgage notes receivable to the buyers. These notes were paid off in November and December 2017. (d) The Company recorded an impairment charge of $7.0 million on this property during the year ended December 31, 2015. (e) The Company recorded an impairment charge of $4.2 million on this property during the year ended December 31, 2015. $5.9 million of the sales proceeds from this sale were held by a qualified intermediary, which is noncash and recorded in deferred charges, goodwill and other assets as of December 31, 2017. See Note 5: Deferred Charges, Goodwill and Other Assets, Net. (f) $15.3 million of the sales proceeds from this sale were held by a qualified intermediary, which is noncash and recorded in deferred charges, goodwill and other assets as of December 31, 2017. See Note 5: Deferred Charges, Goodwill and Other Assets, Net.   2016 The Company disposed of the following office and multi-family properties during the year ended December 31, 2016 (dollars in thousands) :     Realized  Gains  Net Net (losses)/ Disposition # of Sales Carrying Unrealized Date Property/Address Location Bldgs. Proceeds Value Losses, net 03/11/16 2 Independence Way (a) Princeton, New Jersey 1 $ 4,119 $ 4,283 $ (164) 03/24/16 1201 Connecticut Avenue, NW Washington, D.C. 1 90,591 31,827 58,764 04/26/16 125 Broad Street (b) New York, New York 1 192,323 200,183 (7,860) 05/09/16 9200 Edmonston Road Greenbelt, Maryland 1 4,083 (c) 3,837 246 05/18/16 1400 L Street Washington, D.C. 1 68,399 30,053 38,346 07/14/16 600 Parsippany Road Parsippany, New Jersey 1 10,465 (d) 5,875 4,590 07/14/16 4,5,6 Century Drive (e) Parsippany, New Jersey 3 14,533 17,308 (2,775) 08/11/16 Andover Place Andover, Massachusetts 1 39,863 37,150 2,713 09/26/16 222,233 Mount Airy Road (f) Basking Ridge, New Jersey 2 8,817 9,039 (222) 09/27/16 10 Mountainview Road Upper Saddle River, New Jersey 1 18,990 19,571 (581) 11/07/16 100 Willowbrook, 2,3,4 Paragon (g) Freehold, New Jersey 4 14,634 19,377 (4,743) 12/05/16 4 Becker Farm Road Roseland, New Jersey 1 41,400 (h) 31,001 10,399 12/09/16 101,103,105 Eisenhower Parkway Roseland, New Jersey 3 46,423 45,999 424 12/22/16 Capital Office Park, Ivy Lane (i) Greenbelt, Maryland 6 46,570 65,064 (18,494) 12/22/16 100 Walnut Avenue Clark, New Jersey 1 28,428 7,529 20,899 12/22/16 20 Commerce Drive Cranford, New Jersey 1 28,878 13,071 15,807 12/29/16 4200 Parliament Place (j) Lanham, Maryland 1 5,965 5,983 (18) Sub-total 30 664,481 547,150 117,331  Unrealized losses on rental property held for sale (7,665)  Totals 30 $ 664,481 $ 547,150 $ 109,666  (a) The Company recorded an impairment charge of $3.2 million on this property during the year ended December 31, 2015. (b) The Company recorded impairment charges of $83.2 million on this property during the year ended December 31, 2015. (c) The Company transferred the deed for this property to the lender in satisfaction of its obligations. The Company recorded an impairment charge of $3.0 million on this property during the year ended December 31, 2012. (d) $10.5 million of the net sales proceeds from this sale were held by a qualified intermediary. The Company received these proceeds on January 11, 2017. (e) The Company recorded impairment charges of $9.8 million on these properties during the year ended December 31, 2015. (f) The Company recorded impairment charges of $1.0 million on these properties during the year ended December 31, 2015. (g) The Company recorded impairment charges of $7.4 million on these properties during the year ended December 31, 2015. (h) The Company transferred the deed for this property to the lender in satisfaction of its obligations. (i) The Company recorded impairment charges of $66.5 million on these properties during the year ended December 31, 2015. (j) The Company recorded an impairment charge of $4.2 million on this property during the year ended December 31, 2015. 
Mack-Cali Realty LP [Member] | Disposal Group, Held-for-sale, Not Discontinued Operations [Member]
Real Estate Properties [Line Items]
Summary Of Income From Property Held For Sale, Net	The following table summarizes the rental property held for sale, net, as of December 31, 2017: (dollars in thousands)     December 31,  2017 Land $ 37,024 Buildings and improvements 273,388 Less: Accumulated depreciation (126,503) Less: Unrealized losses on properties held for sale (12,331) Rental property held for sale,net $ 171,578   The following table summarizes the rental property held for sale, net, as of December 31, 2016: (dollars in thousands)     December 31,  2016 Land $ 10,934 Buildings and improvements 68,266 Less: Accumulated depreciation (31,792) Less: Unrealized losses on properties held for sale (7,665) Rental property held for sale,net $ 39,743 

Investments In Unconsolidated32

Investments In Unconsolidated Joint Ventures (Tables)	12 Months Ended
	Dec. 31, 2017
Investments In Unconsolidated Joint Ventures [Line Items]
Summary Of Unconsolidated Joint Ventures	  Property Debt  Number of Company's Carrying Value As of December 31, 2017  Apartment Units Effective December 31, December 31, Maturity Interest  Entity / Property Name or Rentable Square Feet (sf) Ownership % (a) 2017 2016 Balance Date Rate  Multi-family  Marbella RoseGarden, L.L.C./ Marbella 412 units 24.27 % $ 14,544 $ 15,150 $ 95,000 05/01/18 4.99 %  RoseGarden Monaco Holdings, L.L.C./ Monaco 523 units (e) - - - - -  Rosewood Morristown, L.L.C. / Metropolitan at 40 Park (b) (c) 130 units 12.50 % 6,834 7,145 53,224 (d) (d)  Riverwalk G Urban Renewal, L.L.C./ RiverTrace at Port Imperial 316 units 22.50 % 8,864 9,707 82,000 11/10/26 3.21 %  Elmajo Urban Renewal Associates, LLC / Lincoln Harbor (Bldg A&C) (f) 355 units 7.50 % - - - - -  Crystal House Apartments Investors LLC / Crystal House (g) 825 units 25.00 % 30,570 30,565 165,000 04/01/20 3.17 %  Riverwalk C Urban Renewal, L.L.C. (h) 360 units 40.00 % 16,844 - - 12/06/21 L+2.75 %  RoseGarden Marbella South, L.L.C./ Marbella II 311 units 24.27 % 16,471 18,050 74,690 03/30/18 L+2.25 % (i)  Estuary Urban Renewal Unit B, LLC / Lincoln Harbor (Bldg B) (f) 227 units 7.50 % - - - - -  Riverpark at Harrison I, L.L.C./ Riverpark at Harrison 141 units 45.00 % 1,604 2,085 30,000 08/01/25 3.70 %  Capitol Place Mezz LLC / Station Townhouses 378 units 50.00 % 40,124 43,073 100,070 07/01/33 4.82 %  Harborside Unit A Urban Renewal, L.L.C. / URL Harborside 762 units 85.00 % 94,429 100,188 189,853 08/01/29 5.197 % (j)  Roseland/Port Imperial Partners, L.P. (k) 836 potential units 20.00 % 1,678 1,678 - - -  RoseGarden Monaco, L.L.C./ San Remo Land (l) 250 potential units 41.67 % - 1,400 - - -  Grand Jersey Waterfront URA, L.L.C./ Liberty Landing 850 potential units 50.00 % 337 337 - - -  Hillsborough 206 Holdings, L.L.C./ Hillsborough 206 160,000 sf 50.00 % 1,962 1,962 - - -  Plaza VIII & IX Associates, L.L.C./ Vacant land (parking operations) (m) 1,225,000 sf 50.00 % - 4,448 - - -   Office  Red Bank Corporate Plaza, L.L.C./ Red Bank 92,878 sf 50.00 % 4,602 4,339 13,876 05/17/18 L+3.00 %  12 Vreeland Associates, L.L.C./ 12 Vreeland Road 139,750 sf 50.00 % 6,734 6,237 9,495 07/01/23 2.87 %  BNES Associates III / Offices at Crystal Lake 106,345 sf 31.25 % 3,369 3,124 4,794 11/01/23 4.76 %  KPG-P 100 IMW JV, LLC / 100 Independence Mall West 339,615 sf (n) - - - - -  Keystone-Penn 1,842,820 sf (n) - - - - -  Keystone-TriState 1,266,384 sf (n) - 2,285 - - -  KPG-MCG Curtis JV, L.L.C./ Curtis Center 885,000 sf (o) - 65,400 - - -   Other  Roseland/North Retail, L.L.C./ Riverwalk at Port Imperial 30,745 sf 20.00 % 1,625 1,706 - - -  South Pier at Harborside / Hyatt Regency Jersey City on the Hudson 350 rooms 50.00 % 440 163 99,135 10/01/26 3.668 %  Other (p) 1,595 1,005 - - -  Totals: $ 252,626 $ 320,047 $ 917,137     (a) Company's effective ownership % represents the Company's entitlement to residual distributions after payments of priority returns, where applicable.  (b) The Company's ownership interests in this venture are subordinate to its partner's preferred capital balance and the Company is not expected to meaningfully participate in the venture's cash flows in the near term.  (c) Through the joint venture, the Company also owns a 12.5 percent interest in a 50,973 square feet retail building ("Shops at 40 Park") and a 25 percent interest in a to-be-built 59 -unit, five story multi-family rental development property ("Lofts at 40 Park").  (d) Property debt balance consists of: (i) an amortizable loan, collateralized by the Metropolitan at 40 Park, with a balance of $36.8 million bears interest at 3.25 percent, matures in September 2020 ; (ii) an amortizable loan, collateralized by the Shops at 40 Park, with a balance of $6.2 million, bears interest at 3.63 percent, matures in August 2018 . On February 3, 2017, the venture obtained a construction loan for the Lofts at 40 Park with a balance of $10.2 million, which bears interest at LIBOR plus 250 basis points and matures in February 2020 and provides, subject to certain conditions, two one -year extension options with a fee of 15 basis points for each year.  (e) On February 28, 2017, 9,122 Series A-1 Units were issued to the joint venture partner as noncash consideration for the partner's approximate 13.8 percent ownership interest in the joint venture. In April 2017, the Company acquired the remaining joint venture interests and increased its ownership interest to 100 percent. See Note 3: Recent Transactions – Consolidation.  (f) On February 15, 2017, the Company sold its 7.5 percent interest in Elmajo Urban Renewal Associates, LLC and Estuary Urban Renewal Unit B, LLC joint ventures that own operating multi-family properties, located in Weehawken, New Jersey for a combined sales price of $5.1 million.  (g) The Company also owns a 50 percent interest in a vacant land to accommodate the development of approximately 295 additional units of which 252 are currently approved.  (h) On December 7, 2017, simultaneous with the financing of the construction loan, the Company converted its 20 percent subordinate interest to 40 percent pari-passu interest.  (i) The construction loan had a maximum borrowing amount of $77.4 million and provided, subject to certain conditions, two one -year extension options with a fee of 25 basis points for each year. On March 31, 2017, the Company exercised its first one -year extension option and concurrently the maximum borrowing amount was reduced to $75 million.  (j) The construction/permanent loan has a maximum borrowing amount of $192 million. The Company owns an 85 percent interest with shared control over major decisions such as, approval of budgets, property financings and leasing guidelines. The development project was placed in service in second quarter 2017.  (k) The Company also owns a 20 percent residual interest in undeveloped land parcels: parcels 6, I, and J that can accommodate the development of 836 apartment units.  (l) On September 21, 2017, the joint venture agreement was terminated. Accordingly, the Company wrote off the carrying value of its investment in the joint venture and recorded a loss of $1.4 million on the disposition of its joint venture interest.  (m) On February 3, 2017, the Company acquired the equity interest of its partner. See Note 3: Recent Transactions - Consolidation.  (n) On January 31, 2017, the Company sold its equity interest in the joint venture. See Note 3: Recent Transactions - Unconsolidated Joint Venture Activity.  (o) Includes undivided interests in the same manner as investments in noncontrolling partnership, pursuant to ASC 970-323-25-12. On September 29, 2017, the Company sold its equity interest to its joint venture partner, which included the retirement of the Company's share in the debt of $75 million. See Note 3: Recent Transactions - Unconsolidated Joint Venture Activity.  (p) The Company owns other interests in various unconsolidated joint ventures, including interests in assets previously owned and interest in ventures whose businesses are related to its core operations. These ventures are not expected to significantly impact the Company's operations in the near term. 
Summary Of Company's Equity In Earnings (Loss) Of Unconsolidated Joint Ventures	   Year Ended December 31,  Entity / Property Name 2017 2016 2015  Multi-family  Marbella RoseGarden, L.L.C./ Marbella $ 334 $ 231 $ 231  RoseGarden Monaco Holdings, L.L.C./ Monaco (265) (937) (1,224)  Rosewood Morristown, L.L.C. / Metropolitan at 40 Park (311) (317) (364)  Riverwalk G Urban Renewal, L.L.C./ RiverTrace at Port Imperial 196 (1,146) (955)  Crystal House Apartments Investors LLC / Crystal House (923) (870) (123)  Riverwalk C Urban Renewal, L.L.C. (653) (58) (306)  RoseGarden Marbella South, L.L.C./ Marbella II 93 (202) -  Estuary Urban Renewal Unit B, LLC / Lincoln Harbor (Bldg B) - - 1  Riverpark at Harrison I, L.L.C./ Riverpark at Harrison (252) (190) (363)  Capitol Place Mezz LLC / Station Townhouses (1,793) (2,440) (3,687)  Harborside Unit A Urban Renewal, L.L.C. / URL Harborside (6,356) (219) -  Roseland/Port Imperial Partners, L.P. (219) (62) (168)  Grand Jersey Waterfront URA, L.L.C./ Liberty Landing (15) (80) (32)  Hillsborough 206 Holdings, L.L.C./ Hillsborough 206 (25) (53) (5)  Plaza VIII & IX Associates, L.L.C./ Vacant land (parking operations) 386 393 344  Office  Red Bank Corporate Plaza, L.L.C./ Red Bank 238 448 392  12 Vreeland Associates, L.L.C./ 12 Vreeland Road 496 347 270  BNES Associates III / Offices at Crystal Lake 89 (15) 115  KPG-P 100 IMW JV, LLC / 100 Independence Mall West - - (800)  Keystone-Penn - 600 3,812  Keystone-TriState - (1,672) (2,182)  KPG-MCG Curtis JV, L.L.C./ Curtis Center (436) (92) 475  Other  Roseland/North Retail, L.L.C./ Riverwalk at Port Imperial (81) (52) (70)  South Pier at Harborside / Hyatt Regency Jersey City on the Hudson (a) 3,277 24,180 3,036  Other 139 994 (1,569)  Company's equity in earnings (loss) of unconsolidated joint ventures (b) $ (6,081) $ 18,788 $ (3,172) (a) Equity in earnings in 2016 includes the effect of distributions received from the joint venture’s refinancing. See Recent Joint Venture Transactions following in this footnote. (b) Amounts are net of amortization of basis differences of $792 , $436 and $336 for the years ended December 31, 2017, 2016 and 2015, respectively.
Summary Of Financial Position Of Unconsolidated Joint Ventures	   December 31, December 31,  2017 2016  Assets:  Rental property, net $ 931,419 $ 1,746,233  Other assets 207,903 278,289  Total assets $ 1,139,322 $ 2,024,522  Liabilities and partners'/  members' capital:  Mortgages and loans payable $ 689,412 $ 1,350,973  Other liabilities 80,746 247,212  Partners'/members' capital 369,164 426,337  Total liabilities and  partners'/members' capital $ 1,139,322 $ 2,024,522 
Summary Of Results Of Operations Of Unconsolidated Joint Ventures	   Year Ended December 31,  2017 2016 2015  Total revenues $ 358,751 $ 377,711 $ 318,980  Operating and other expenses (297,492) (262,703) (220,982)  Depreciation and amortization (31,020) (75,512) (71,711)  Interest expense (25,822) (58,390) (52,972)  Net income (loss) $ 4,417 $ (18,894) $ (26,685) 
Mack-Cali Realty LP [Member]
Investments In Unconsolidated Joint Ventures [Line Items]
Summary Of Unconsolidated Joint Ventures	  Property Debt  Number of Company's Carrying Value As of December 31, 2017  Apartment Units Effective December 31, December 31, Maturity Interest  Entity / Property Name or Rentable Square Feet (sf) Ownership % (a) 2017 2016 Balance Date Rate  Multi-family  Marbella RoseGarden, L.L.C./ Marbella 412 units 24.27 % $ 14,544 $ 15,150 $ 95,000 05/01/18 4.99 %  RoseGarden Monaco Holdings, L.L.C./ Monaco 523 units (e) - - - - -  Rosewood Morristown, L.L.C. / Metropolitan at 40 Park (b) (c) 130 units 12.50 % 6,834 7,145 53,224 (d) (d)  Riverwalk G Urban Renewal, L.L.C./ RiverTrace at Port Imperial 316 units 22.50 % 8,864 9,707 82,000 11/10/26 3.21 %  Elmajo Urban Renewal Associates, LLC / Lincoln Harbor (Bldg A&C) (f) 355 units 7.50 % - - - - -  Crystal House Apartments Investors LLC / Crystal House (g) 825 units 25.00 % 30,570 30,565 165,000 04/01/20 3.17 %  Riverwalk C Urban Renewal, L.L.C. (h) 360 units 40.00 % 16,844 - - 12/06/21 L+2.75 %  RoseGarden Marbella South, L.L.C./ Marbella II 311 units 24.27 % 16,471 18,050 74,690 03/30/18 L+2.25 % (i)  Estuary Urban Renewal Unit B, LLC / Lincoln Harbor (Bldg B) (f) 227 units 7.50 % - - - - -  Riverpark at Harrison I, L.L.C./ Riverpark at Harrison 141 units 45.00 % 1,604 2,085 30,000 08/01/25 3.70 %  Capitol Place Mezz LLC / Station Townhouses 378 units 50.00 % 40,124 43,073 100,070 07/01/33 4.82 %  Harborside Unit A Urban Renewal, L.L.C. / URL Harborside 762 units 85.00 % 94,429 100,188 189,853 08/01/29 5.197 % (j)  Roseland/Port Imperial Partners, L.P. (k) 836 potential units 20.00 % 1,678 1,678 - - -  RoseGarden Monaco, L.L.C./ San Remo Land (l) 250 potential units 41.67 % - 1,400 - - -  Grand Jersey Waterfront URA, L.L.C./ Liberty Landing 850 potential units 50.00 % 337 337 - - -  Hillsborough 206 Holdings, L.L.C./ Hillsborough 206 160,000 sf 50.00 % 1,962 1,962 - - -  Plaza VIII & IX Associates, L.L.C./ Vacant land (parking operations) (m) 1,225,000 sf 50.00 % - 4,448 - - -   Office  Red Bank Corporate Plaza, L.L.C./ Red Bank 92,878 sf 50.00 % 4,602 4,339 13,876 05/17/18 L+3.00 %  12 Vreeland Associates, L.L.C./ 12 Vreeland Road 139,750 sf 50.00 % 6,734 6,237 9,495 07/01/23 2.87 %  BNES Associates III / Offices at Crystal Lake 106,345 sf 31.25 % 3,369 3,124 4,794 11/01/23 4.76 %  KPG-P 100 IMW JV, LLC / 100 Independence Mall West 339,615 sf (n) - - - - -  Keystone-Penn 1,842,820 sf (n) - - - - -  Keystone-TriState 1,266,384 sf (n) - 2,285 - - -  KPG-MCG Curtis JV, L.L.C./ Curtis Center 885,000 sf (o) - 65,400 - - -   Other  Roseland/North Retail, L.L.C./ Riverwalk at Port Imperial 30,745 sf 20.00 % 1,625 1,706 - - -  South Pier at Harborside / Hyatt Regency Jersey City on the Hudson 350 rooms 50.00 % 440 163 99,135 10/01/26 3.668 %  Other (p) 1,595 1,005 - - -  Totals: $ 252,626 $ 320,047 $ 917,137     (a) Company's effective ownership % represents the Company's entitlement to residual distributions after payments of priority returns, where applicable.  (b) The Company's ownership interests in this venture are subordinate to its partner's preferred capital balance and the Company is not expected to meaningfully participate in the venture's cash flows in the near term.  (c) Through the joint venture, the Company also owns a 12.5 percent interest in a 50,973 square feet retail building ("Shops at 40 Park") and a 25 percent interest in a to-be-built 59 -unit, five story multi-family rental development property ("Lofts at 40 Park").  (d) Property debt balance consists of: (i) an amortizable loan, collateralized by the Metropolitan at 40 Park, with a balance of $36.8 million bears interest at 3.25 percent, matures in September 2020 ; (ii) an amortizable loan, collateralized by the Shops at 40 Park, with a balance of $6.2 million, bears interest at 3.63 percent, matures in August 2018 . On February 3, 2017, the venture obtained a construction loan for the Lofts at 40 Park with a balance of $10.2 million, which bears interest at LIBOR plus 250 basis points and matures in February 2020 and provides, subject to certain conditions, two one -year extension options with a fee of 15 basis points for each year.  (e) On February 28, 2017, 9,122 Series A-1 Units were issued to the joint venture partner as noncash consideration for the partner's approximate 13.8 percent ownership interest in the joint venture. In April 2017, the Company acquired the remaining joint venture interests and increased its ownership interest to 100 percent. See Note 3: Recent Transactions – Consolidation.  (f) On February 15, 2017, the Company sold its 7.5 percent interest in Elmajo Urban Renewal Associates, LLC and Estuary Urban Renewal Unit B, LLC joint ventures that own operating multi-family properties, located in Weehawken, New Jersey for a combined sales price of $5.1 million.  (g) The Company also owns a 50 percent interest in a vacant land to accommodate the development of approximately 295 additional units of which 252 are currently approved.  (h) On December 7, 2017, simultaneous with the financing of the construction loan, the Company converted its 20 percent subordinate interest to 40 percent pari-passu interest.  (i) The construction loan had a maximum borrowing amount of $77.4 million and provided, subject to certain conditions, two one -year extension options with a fee of 25 basis points for each year. On March 31, 2017, the Company exercised its first one -year extension option and concurrently the maximum borrowing amount was reduced to $75 million.  (j) The construction/permanent loan has a maximum borrowing amount of $192 million. The Company owns an 85 percent interest with shared control over major decisions such as, approval of budgets, property financings and leasing guidelines. The development project was placed in service in second quarter 2017.  (k) The Company also owns a 20 percent residual interest in undeveloped land parcels: parcels 6, I, and J that can accommodate the development of 836 apartment units.  (l) On September 21, 2017, the joint venture agreement was terminated. Accordingly, the Company wrote off the carrying value of its investment in the joint venture and recorded a loss of $1.4 million on the disposition of its joint venture interest.  (m) On February 3, 2017, the Company acquired the equity interest of its partner. See Note 3: Recent Transactions - Consolidation.  (n) On January 31, 2017, the Company sold its equity interest in the joint venture. See Note 3: Recent Transactions - Unconsolidated Joint Venture Activity.  (o) Includes undivided interests in the same manner as investments in noncontrolling partnership, pursuant to ASC 970-323-25-12. On September 29, 2017, the Company sold its equity interest to its joint venture partner, which included the retirement of the Company's share in the debt of $75 million. See Note 3: Recent Transactions - Unconsolidated Joint Venture Activity.  (p) The Company owns other interests in various unconsolidated joint ventures, including interests in assets previously owned and interest in ventures whose businesses are related to its core operations. These ventures are not expected to significantly impact the Company's operations in the near term. 
Summary Of Company's Equity In Earnings (Loss) Of Unconsolidated Joint Ventures	   Year Ended December 31,  Entity / Property Name 2017 2016 2015  Multi-family  Marbella RoseGarden, L.L.C./ Marbella $ 334 $ 231 $ 231  RoseGarden Monaco Holdings, L.L.C./ Monaco (265) (937) (1,224)  Rosewood Morristown, L.L.C. / Metropolitan at 40 Park (311) (317) (364)  Riverwalk G Urban Renewal, L.L.C./ RiverTrace at Port Imperial 196 (1,146) (955)  Crystal House Apartments Investors LLC / Crystal House (923) (870) (123)  Riverwalk C Urban Renewal, L.L.C. (653) (58) (306)  RoseGarden Marbella South, L.L.C./ Marbella II 93 (202) -  Estuary Urban Renewal Unit B, LLC / Lincoln Harbor (Bldg B) - - 1  Riverpark at Harrison I, L.L.C./ Riverpark at Harrison (252) (190) (363)  Capitol Place Mezz LLC / Station Townhouses (1,793) (2,440) (3,687)  Harborside Unit A Urban Renewal, L.L.C. / URL Harborside (6,356) (219) -  Roseland/Port Imperial Partners, L.P. (219) (62) (168)  Grand Jersey Waterfront URA, L.L.C./ Liberty Landing (15) (80) (32)  Hillsborough 206 Holdings, L.L.C./ Hillsborough 206 (25) (53) (5)  Plaza VIII & IX Associates, L.L.C./ Vacant land (parking operations) 386 393 344  Office  Red Bank Corporate Plaza, L.L.C./ Red Bank 238 448 392  12 Vreeland Associates, L.L.C./ 12 Vreeland Road 496 347 270  BNES Associates III / Offices at Crystal Lake 89 (15) 115  KPG-P 100 IMW JV, LLC / 100 Independence Mall West - - (800)  Keystone-Penn - 600 3,812  Keystone-TriState - (1,672) (2,182)  KPG-MCG Curtis JV, L.L.C./ Curtis Center (436) (92) 475  Other  Roseland/North Retail, L.L.C./ Riverwalk at Port Imperial (81) (52) (70)  South Pier at Harborside / Hyatt Regency Jersey City on the Hudson (a) 3,277 24,180 3,036  Other 139 994 (1,569)  Company's equity in earnings (loss) of unconsolidated joint ventures (b) $ (6,081) $ 18,788 $ (3,172) (a) Equity in earnings in 2016 includes the effect of distributions received from the joint venture’s refinancing. See Recent Joint Venture Transactions following in this footnote. (b) Amounts are net of amortization of basis differences of $792 , $436 and $336 for the years ended December 31, 2017, 2016 and 2015, respectively.
Summary Of Financial Position Of Unconsolidated Joint Ventures	   December 31, December 31,  2017 2016  Assets:  Rental property, net $ 931,419 $ 1,746,233  Other assets 207,903 278,289  Total assets $ 1,139,322 $ 2,024,522  Liabilities and partners'/  members' capital:  Mortgages and loans payable $ 689,412 $ 1,350,973  Other liabilities 80,746 247,212  Partners'/members' capital 369,164 426,337  Total liabilities and  partners'/members' capital $ 1,139,322 $ 2,024,522 
Summary Of Results Of Operations Of Unconsolidated Joint Ventures	   Year Ended December 31,  2017 2016 2015  Total revenues $ 358,751 $ 377,711 $ 318,980  Operating and other expenses (297,492) (262,703) (220,982)  Depreciation and amortization (31,020) (75,512) (71,711)  Interest expense (25,822) (58,390) (52,972)  Net income (loss) $ 4,417 $ (18,894) $ (26,685) 

Deferred Charges, Goodwill An33

Deferred Charges, Goodwill And Other Assets, Net (Tables)	12 Months Ended
	Dec. 31, 2017
Deferred Charges, Goodwill And Other Assets [Line Items]
Schedule Of Deferred Charges, Goodwill And Other Assets	   December 31,  (dollars in thousands) 2017 2016  Deferred leasing costs $ 199,515 $ 220,947  Deferred financing costs - unsecured revolving credit facility (a) 4,945 5,400  204,460 226,347  Accumulated amortization (98,956) (107,359)  Deferred charges, net 105,504 118,988  Notes receivable (b) 50,167 13,251  In-place lease values, related intangibles and other assets, net (c) (d) 102,757 72,046  Goodwill (e) 2,945 2,945  Prepaid expenses and other assets, net (f) 80,947 60,720   Total deferred charges, goodwill and other assets, net $ 342,320 $ 267,950  (a) Deferred financing costs related to all other debt liabilities (other than for the unsecured revolving credit facility) are netted against those debt liabilities for all periods presented. See Note 2: Significant Accounting Policies – Deferred Financing Costs. (b) Includes as of December 31, 2017 : a mortgage receivable with a balance of $ 45.7 million (acquired in August 2017) which bears interest at 5.85 percent and matures in July 2019 , with a three -month extension option and an interest-free note receivable with a net present value of $2.5 million which matures in April 2023 . The Company believes these balances are fully collectible. (c) In accordance with ASC 805, Business Combinations, the Company recognizes rental revenue of acquired above and below market lease intangibles over the terms of the respective leases. The impact of amortizing the acquired above and below-market lease intangibles increased revenue by approximately $ 7.9 million, $1.9 million and $0.2 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. The following table summarizes, as of December 31, 2017 , the scheduled amortization of the Company’s acquired above and below-market lease intangibles for each of the five succeeding years (dollars in thousands) .     Acquired Above- Acquired Below-  Market Lease Market Lease Total  Year Intangibles Intangibles Amortization  2018 $ (5,084) $ 6,888 $ 1,804  2019 (4,716) 5,183 467  2020 (3,398) 4,304 906  2021 (2,779) 4,186 1,407  2022 (2,665) 4,063 1,398  (d) The value of acquired in-place lease intangibles are amortized to expense over the remaining initial terms of the respective leases. The impact of the amortization of acquired in-place lease values is included in depreciation and amortization expense and amounted to approximately $32.2 million, $14.3 million and $1.4 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. The following table summarizes, as of December 31, 2017 , the scheduled amortization of the Company’s acquired in-place lease values for each of the five succeeding years (dollars in thousands) .    Year  2018 $ 10,657  2019 8,406  2020 7,078  2021 6,347  2022 5,526   (e) All goodwill is attributable to the Company’s Multi-family Services segment. (f) Includes as of December 31, 2017 , $26.9 million of proceeds from property sales held by a qualified intermediary.
Schedule Of Fair Value Of The Derivative Financial Instruments	   Fair Value  Asset Derivatives designated December 31,  as hedging instruments 2017 2016 Balance sheet location  Interest rate swaps $ 8,060 $ 2,847 Deferred charges, goodwill and other assets 
Schedule Of Cash Flow Hedging, Derivative Financial Instruments On The Income Statement	   Derivatives in Cash Flow Hedging Relationships Amount of Gain or (Loss) Recognized in OCI on Derivative (Effective Portion) Location of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion) Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion) Location of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing) Amount of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion, Reclassification for Forecasted Transactions No Longer Probable of Occurring and Amount Excluded from Effectiveness Testing)  2017 2016 2015 2017 2016 2015 2017 2016 2015  Year ended December 31,   Interest rate swaps $ 2,869 $ (1,183) $ - Interest expense $ (2,381) $ (3,398) $ - Interest and other investment income (loss) $ (37) $ 631 $ -  
Acquired Above And Below Market Lease Intangibles [Member]
Deferred Charges, Goodwill And Other Assets [Line Items]
Summary Of Scheduled Amortization	   Acquired Above- Acquired Below-  Market Lease Market Lease Total  Year Intangibles Intangibles Amortization  2018 $ (5,084) $ 6,888 $ 1,804  2019 (4,716) 5,183 467  2020 (3,398) 4,304 906  2021 (2,779) 4,186 1,407  2022 (2,665) 4,063 1,398 
In-Place Leases [Member]
Deferred Charges, Goodwill And Other Assets [Line Items]
Summary Of Scheduled Amortization	   Year  2018 $ 10,657  2019 8,406  2020 7,078  2021 6,347  2022 5,526 
Mack-Cali Realty LP [Member]
Deferred Charges, Goodwill And Other Assets [Line Items]
Schedule Of Deferred Charges, Goodwill And Other Assets	   December 31,  (dollars in thousands) 2017 2016  Deferred leasing costs $ 199,515 $ 220,947  Deferred financing costs - unsecured revolving credit facility (a) 4,945 5,400  204,460 226,347  Accumulated amortization (98,956) (107,359)  Deferred charges, net 105,504 118,988  Notes receivable (b) 50,167 13,251  In-place lease values, related intangibles and other assets, net (c) (d) 102,757 72,046  Goodwill (e) 2,945 2,945  Prepaid expenses and other assets, net (f) 80,947 60,720   Total deferred charges, goodwill and other assets, net $ 342,320 $ 267,950  (a) Deferred financing costs related to all other debt liabilities (other than for the unsecured revolving credit facility) are netted against those debt liabilities for all periods presented. See Note 2: Significant Accounting Policies – Deferred Financing Costs. (b) Includes as of December 31, 2017 : a mortgage receivable with a balance of $ 45.7 million (acquired in August 2017) which bears interest at 5.85 percent and matures in July 2019 , with a three -month extension option and an interest-free note receivable with a net present value of $2.5 million which matures in April 2023 . The Company believes these balances are fully collectible. (c) In accordance with ASC 805, Business Combinations, the Company recognizes rental revenue of acquired above and below market lease intangibles over the terms of the respective leases. The impact of amortizing the acquired above and below-market lease intangibles increased revenue by approximately $ 7.9 million, $1.9 million and $0.2 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. The following table summarizes, as of December 31, 2017 , the scheduled amortization of the Company’s acquired above and below-market lease intangibles for each of the five succeeding years (dollars in thousands) .     Acquired Above- Acquired Below-  Market Lease Market Lease Total  Year Intangibles Intangibles Amortization  2018 $ (5,084) $ 6,888 $ 1,804  2019 (4,716) 5,183 467  2020 (3,398) 4,304 906  2021 (2,779) 4,186 1,407  2022 (2,665) 4,063 1,398  (d) The value of acquired in-place lease intangibles are amortized to expense over the remaining initial terms of the respective leases. The impact of the amortization of acquired in-place lease values is included in depreciation and amortization expense and amounted to approximately $32.2 million, $14.3 million and $1.4 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. The following table summarizes, as of December 31, 2017 , the scheduled amortization of the Company’s acquired in-place lease values for each of the five succeeding years (dollars in thousands) .    Year  2018 $ 10,657  2019 8,406  2020 7,078  2021 6,347  2022 5,526   (e) All goodwill is attributable to the Company’s Multi-family Services segment. (f) Includes as of December 31, 2017 , $26.9 million of proceeds from property sales held by a qualified intermediary.
Schedule Of Fair Value Of The Derivative Financial Instruments	   Fair Value  Asset Derivatives designated December 31,  as hedging instruments 2017 2016 Balance sheet location  Interest rate swaps $ 8,060 $ 2,847 Deferred charges, goodwill and other assets 
Schedule Of Cash Flow Hedging, Derivative Financial Instruments On The Income Statement	   Derivatives in Cash Flow Hedging Relationships Amount of Gain or (Loss) Recognized in OCI on Derivative (Effective Portion) Location of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion) Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion) Location of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing) Amount of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion, Reclassification for Forecasted Transactions No Longer Probable of Occurring and Amount Excluded from Effectiveness Testing)  2017 2016 2015 2017 2016 2015 2017 2016 2015  Year ended December 31,   Interest rate swaps $ 2,869 $ (1,183) $ - Interest expense $ (2,381) $ (3,398) $ - Interest and other investment income (loss) $ (37) $ 631 $ -  
Mack-Cali Realty LP [Member] | Acquired Above And Below Market Lease Intangibles [Member]
Deferred Charges, Goodwill And Other Assets [Line Items]
Summary Of Scheduled Amortization	   Acquired Above- Acquired Below-  Market Lease Market Lease Total  Year Intangibles Intangibles Amortization  2018 $ (5,084) $ 6,888 $ 1,804  2019 (4,716) 5,183 467  2020 (3,398) 4,304 906  2021 (2,779) 4,186 1,407  2022 (2,665) 4,063 1,398 
Mack-Cali Realty LP [Member] | In-Place Leases [Member]
Deferred Charges, Goodwill And Other Assets [Line Items]
Summary Of Scheduled Amortization	   Year  2018 $ 10,657  2019 8,406  2020 7,078  2021 6,347  2022 5,526 

Restricted Cash (Tables)

Restricted Cash (Tables)	12 Months Ended
	Dec. 31, 2017
Restricted Cash [Line Items]
Schedule Of Restricted Cash	   December 31,  2017 2016  Security deposits $ 9,446 $ 8,778  Escrow and other reserve funds 30,346 45,174   Total restricted cash $ 39,792 $ 53,952 
Mack-Cali Realty LP [Member]
Restricted Cash [Line Items]
Schedule Of Restricted Cash	   December 31,  2017 2016  Security deposits $ 9,446 $ 8,778  Escrow and other reserve funds 30,346 45,174   Total restricted cash $ 39,792 $ 53,952 

Senior Unsecured Notes (Tables)

Senior Unsecured Notes (Tables) - Unsecured Note [Member]	12 Months Ended
	Dec. 31, 2017
Debt Instrument [Line Items]
Summary Of Senior Unsecured Notes	    December 31, December 31, Effective  2017 2016 Rate (1)  2.500% Senior Unsecured Notes, due December 15, 2017 (2) - $ 250,000 2.803 %  4.500% Senior Unsecured Notes, due April 18, 2022 $ 300,000 300,000 4.612 %  3.150% Senior Unsecured Notes, due May 15, 2023 275,000 275,000 3.517 %  Principal balance outstanding 575,000 825,000  Adjustment for unamortized debt discount (3,505) (4,430)  Unamortized deferred financing costs (2,350) (3,215)   Total senior unsecured notes, net $ 569,145 $ 817,355  (1) Includes the cost of terminated treasury lock agreements (if any), offering and other transaction costs and the discount/premium on the notes, as applicable. (2) T he Company repaid these notes at maturity using available cash and borrowings under the Company’s unsecured revolving credit facility.
Mack-Cali Realty LP [Member]
Debt Instrument [Line Items]
Summary Of Senior Unsecured Notes	    December 31, December 31, Effective  2017 2016 Rate (1)  2.500% Senior Unsecured Notes, due December 15, 2017 (2) - $ 250,000 2.803 %  4.500% Senior Unsecured Notes, due April 18, 2022 $ 300,000 300,000 4.612 %  3.150% Senior Unsecured Notes, due May 15, 2023 275,000 275,000 3.517 %  Principal balance outstanding 575,000 825,000  Adjustment for unamortized debt discount (3,505) (4,430)  Unamortized deferred financing costs (2,350) (3,215)   Total senior unsecured notes, net $ 569,145 $ 817,355  (1) Includes the cost of terminated treasury lock agreements (if any), offering and other transaction costs and the discount/premium on the notes, as applicable. (2) T he Company repaid these notes at maturity using available cash and borrowings under the Company’s unsecured revolving credit facility.

Unsecured Revolving Credit Fa36

Unsecured Revolving Credit Facility And Term Loans (Tables)	12 Months Ended
	Dec. 31, 2017
Unsecured Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Schedule Of Unsecured Credit Rating And Facility Fee	   Operating Partnership's Interest Rate -  Unsecured Debt Ratings: Applicable Basis Points Facility Fee  Higher of S&P or Moody's Above LIBOR Basis Points  No ratings or less than BBB-/Baa3 170.0 35.0  BBB- or Baa3 (current since January 2017 amendment) 130.0 30.0  BBB or Baa2 110.0 20.0  BBB+ or Baa1 100.0 15.0  A- or A3 or higher 92.5 12.5 
2017 Credit Facility [Member]
Debt Instrument [Line Items]
Schedule Of Interest Rates On Outstanding Borrowings, Alternate Base Rate Loans, And Facility Fee	  Interest Rate -  Applicable Basis Points  Operating Partnership's Interest Rate - Above LIBOR for  Unsecured Debt Ratings: Applicable Basis Points Alternate Base Rate Facility Fee  Higher of S&P or Moody's Above LIBOR Loans Basis Points  No ratings or less than BBB-/Baa3 155.0 55.0 30.0  BBB- or Baa3 (current interest rate based on Company's election) 120.0 20.0 25.0  BBB or Baa2 100.0 0.0 20.0  BBB+ or Baa1 90.0 0.0 15.0  A- or A3 or higher 87.5 0.0 12.5 
Schedule Of Defined Leverage Ratio, Including Interest Rate, Alternate Base Rate Loans, And Facility Fee	  Interest Rate -  Applicable Basis Points  Interest Rate - Above LIBOR for  Applicable Basis Alternate Base Rate Facility Fee  Total Leverage Ratio Points above LIBOR Loans Basis Points  <45% 125.0 25.0 20.0  ≥45% and <50% (current ratio) 130.0 30.0 25.0  ≥50% and <55% 135.0 35.0 30.0  ≥55% 160.0 60.0 35.0 
Mack-Cali Realty LP [Member] | Unsecured Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Schedule Of Unsecured Credit Rating And Facility Fee	   Operating Partnership's Interest Rate -  Unsecured Debt Ratings: Applicable Basis Points Facility Fee  Higher of S&P or Moody's Above LIBOR Basis Points  No ratings or less than BBB-/Baa3 170.0 35.0  BBB- or Baa3 (current since January 2017 amendment) 130.0 30.0  BBB or Baa2 110.0 20.0  BBB+ or Baa1 100.0 15.0  A- or A3 or higher 92.5 12.5 
Mack-Cali Realty LP [Member] | 2017 Credit Facility [Member]
Debt Instrument [Line Items]
Schedule Of Interest Rates On Outstanding Borrowings, Alternate Base Rate Loans, And Facility Fee	  Interest Rate -  Applicable Basis Points  Operating Partnership's Interest Rate - Above LIBOR for  Unsecured Debt Ratings: Applicable Basis Points Alternate Base Rate Facility Fee  Higher of S&P or Moody's Above LIBOR Loans Basis Points  No ratings or less than BBB-/Baa3 155.0 55.0 30.0  BBB- or Baa3 (current interest rate based on Company's election) 120.0 20.0 25.0  BBB or Baa2 100.0 0.0 20.0  BBB+ or Baa1 90.0 0.0 15.0  A- or A3 or higher 87.5 0.0 12.5 
Schedule Of Defined Leverage Ratio, Including Interest Rate, Alternate Base Rate Loans, And Facility Fee	  Interest Rate -  Applicable Basis Points  Interest Rate - Above LIBOR for  Applicable Basis Alternate Base Rate Facility Fee  Total Leverage Ratio Points above LIBOR Loans Basis Points  <45% 125.0 25.0 20.0  ≥45% and <50% (current ratio) 130.0 30.0 25.0  ≥50% and <55% 135.0 35.0 30.0  ≥55% 160.0 60.0 35.0 
2016 Term Loan [Member]
Debt Instrument [Line Items]
Schedule Of Interest Rate On Outstanding Borrowings Payable	   Operating Partnership's Interest Rate -  Unsecured Debt Ratings: Applicable Basis Points  Higher of S&P or Moody's Above LIBOR  No ratings or less than BBB-/Baa3 185.0  BBB- or Baa3 (current interest rate based on Company's election) 140.0  BBB or Baa2 115.0  BBB+ or Baa1 100.0  A- or A3 or higher 90.0 
Schedule Of Defined Leverage Ratio	   Interest Rate -  Applicable Basis  Total Leverage Ratio Points above LIBOR  < 45% 145.0  ≥ 45% and < 50% (current ratio) 155.0  ≥ 50% and < 55% 165.0  ≥ 55% 195.0 
2016 Term Loan [Member] | Mack-Cali Realty LP [Member]
Debt Instrument [Line Items]
Schedule Of Interest Rate On Outstanding Borrowings Payable	   Operating Partnership's Interest Rate -  Unsecured Debt Ratings: Applicable Basis Points  Higher of S&P or Moody's Above LIBOR  No ratings or less than BBB-/Baa3 185.0  BBB- or Baa3 (current interest rate based on Company's election) 140.0  BBB or Baa2 115.0  BBB+ or Baa1 100.0  A- or A3 or higher 90.0 
Schedule Of Defined Leverage Ratio	   Interest Rate -  Applicable Basis  Total Leverage Ratio Points above LIBOR  < 45% 145.0  ≥ 45% and < 50% (current ratio) 155.0  ≥ 50% and < 55% 165.0  ≥ 55% 195.0 

Mortgages, Loans Payable And 37

Mortgages, Loans Payable And Other Obligations (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Instrument [Line Items]
Summary Of Mortgages, Loans Payable And Other Obligations	   Effective December 31, December 31,  Property/Project Name Lender Rate (a) 2017 2016 Maturity  Curtis Center (b) CCRE & PREFG LIBOR+5.91 % - $ 75,000 -  Chase II (c) Fifth Third Bank LIBOR+2.25 % - 34,708 -  23 Main Street Berkadia CMBS 5.59 % $ 27,090 27,838 09/01/18  Port Imperial 4/5 Hotel (d) Fifth Third Bank & Santander LIBOR+4.50 % 43,674 14,919 10/06/18  Harborside Plaza 5 (e) The Northwestern Mutual Life Insurance Co. 6.84 % 209,257 213,640 11/01/18  & New York Life Insurance Co.  Insurance Co.  One River Center (f) Guardian Life Insurance Co. 7.31 % 40,485 41,197 02/01/19  Park Square Wells Fargo Bank N.A. LIBOR+1.87 % 26,567 27,500 04/10/19  250 Johnson (g) M&T Bank LIBOR+2.35 % 32,491 2,440 05/20/19  Portside 5/6 (h) Citizens Bank LIBOR+2.50 % 45,778 - 09/29/19  Port Imperial South 11 (i) JPMorgan Chase LIBOR+2.35 % 46,113 14,073 11/24/19  Worcester (j) Citizens Bank LIBOR+2.50 % 37,821 - 12/10/19  Monaco (k) The Northwestern Mutual Life Insurance Co. 3.15 % 169,987 - 02/01/21  Port Imperial South 4/5 Retail American General Life & A/G PC 4.56 % 4,000 4,000 12/01/21  The Chase at Overlook Ridge New York Community Bank 3.74 % - 72,500 02/01/23  Portside 7 CBRE Capital Markets/FreddieMac 3.57 % 58,998 58,998 08/01/23  Alterra I & II Capital One/FreddieMac 3.85 % 100,000 - 02/01/24  The Chase at Overlook Ridge and Chase II (c) New York Community Bank 3.74 % 135,750 - 01/01/25  101 Hudson Wells Fargo CMBS 3.20 % 250,000 250,000 10/11/26  Short Hills Portfolio (l) Wells Fargo CMBS 4.15 % 124,500 - 04/01/27  150 Main St. Natixis Real Estate Capital LLC 4.48 % 41,000 26,642 08/05/27  Port Imperial South 4/5 Garage American General Life & A/G PC 4.85 % 32,600 32,600 12/01/29   Principal balance outstanding 1,426,111 896,055  Unamortized deferred financing costs (7,976) (7,470)   Total mortgages, loans payable and other obligations, net $ 1,418,135 $ 888,585      (a) Reflects effective rate of debt, including deferred financing costs, comprised of the cost of terminated treasury lock agreements (if any), debt initiation costs,  mark-to-market adjustment of acquired debt and other transaction costs, as applicable.  (b) The Company owned a 50 percent tenants-in-common interest in the Curtis Center property. On September 29, 2017, the Company sold its equity interest to  its joint venture partner, which included the retirement of this $75 million loan balance.  (c) The Chase II construction loan was paid off on December 5, 2017 using the proceeds of a new combined mortgage loan secured by The Chase at Overlook Ridge  and Chase II.  (d) This construction loan has a maximum borrowing capacity of $94 million and provides, subject to certain conditions, two one -year extension options with a fee  of 20 basis points for each year. See Note 12: Commitments and Contingencies - Construction Projects.  (e) On January 8, 2018, the Company prepaid this loan in full upon payment of a fee of approximately $8.4 million using borrowings from the Company's  unsecured revolving credit facility.  (f) Mortgage is collateralized by the three properties comprising One River Center.  (g) This construction loan has a maximum borrowing capacity of $42 million and provides, subject to certain conditions, a one -year extension option with a fee  of 25 basis points. See Note 12: Commitments and Contingencies - Construction Projects.  (h) This construction loan has a maximum borrowing capacity of $73 million and provides, subject to certain conditions, two one -year extension options with a fee  of 15 basis points each year. See Note 12: Commitments and Contingencies - Construction Projects.  (i) This construction loan has a maximum borrowing capacity of $78 million and provides, subject to certain conditions, two one -year extension options with a fee  of 15 basis points each year. See Note 12: Commitments and Contingencies - Construction Projects.  (j) This construction loan has a maximum borrowing capacity of $58 million and provides, subject to certain conditions, two one -year extension options with a fee  of 15 basis points each year. See Note 12: Commitments and Contingencies - Construction Projects.  (k) This mortgage loan, which includes unamortized fair value adjustment of $5.0 million as of December 31, 2017, was assumed by the  Company in April 2017 with the consolidation of all the interests in Monaco Towers. See Note 3: Recent Transactions - Consolidations.  (l) This mortgage loan was obtained by the Company in March 2017 to partially fund the acquisition of the Short Hills/Madison portfolio. 
Schedule Of Principal Payments	   Scheduled Principal  Period Amortization Maturities Total  2018 (a) $ 6,977 $ 275,210 $ 282,187  2019 665 576,489 577,154  2020 2,903 325,000 327,903  2021 3,227 318,800 322,027  2022 3,284 300,000 303,284  Thereafter 10,642 997,927 1,008,569  Sub-total 27,698 2,793,426 2,821,124  Adjustment for unamortized debt  discount/premium, net  December 31, 2017 (3,505) - (3,505)  Unamortized mark to market 4,987 - 4,987  Unamortized deferred financing costs (13,038) (13,038)   Totals/Weighted Average $ 16,142 $ 2,793,426 $ 2,809,568  (a) Includes a mortgage payable amount of approximately $209 million that the Company prepaid in January 2018.
Mack-Cali Realty LP [Member]
Debt Instrument [Line Items]
Summary Of Mortgages, Loans Payable And Other Obligations	   Effective December 31, December 31,  Property/Project Name Lender Rate (a) 2017 2016 Maturity  Curtis Center (b) CCRE & PREFG LIBOR+5.91 % - $ 75,000 -  Chase II (c) Fifth Third Bank LIBOR+2.25 % - 34,708 -  23 Main Street Berkadia CMBS 5.59 % $ 27,090 27,838 09/01/18  Port Imperial 4/5 Hotel (d) Fifth Third Bank & Santander LIBOR+4.50 % 43,674 14,919 10/06/18  Harborside Plaza 5 (e) The Northwestern Mutual Life Insurance Co. 6.84 % 209,257 213,640 11/01/18  & New York Life Insurance Co.  Insurance Co.  One River Center (f) Guardian Life Insurance Co. 7.31 % 40,485 41,197 02/01/19  Park Square Wells Fargo Bank N.A. LIBOR+1.87 % 26,567 27,500 04/10/19  250 Johnson (g) M&T Bank LIBOR+2.35 % 32,491 2,440 05/20/19  Portside 5/6 (h) Citizens Bank LIBOR+2.50 % 45,778 - 09/29/19  Port Imperial South 11 (i) JPMorgan Chase LIBOR+2.35 % 46,113 14,073 11/24/19  Worcester (j) Citizens Bank LIBOR+2.50 % 37,821 - 12/10/19  Monaco (k) The Northwestern Mutual Life Insurance Co. 3.15 % 169,987 - 02/01/21  Port Imperial South 4/5 Retail American General Life & A/G PC 4.56 % 4,000 4,000 12/01/21  The Chase at Overlook Ridge New York Community Bank 3.74 % - 72,500 02/01/23  Portside 7 CBRE Capital Markets/FreddieMac 3.57 % 58,998 58,998 08/01/23  Alterra I & II Capital One/FreddieMac 3.85 % 100,000 - 02/01/24  The Chase at Overlook Ridge and Chase II (c) New York Community Bank 3.74 % 135,750 - 01/01/25  101 Hudson Wells Fargo CMBS 3.20 % 250,000 250,000 10/11/26  Short Hills Portfolio (l) Wells Fargo CMBS 4.15 % 124,500 - 04/01/27  150 Main St. Natixis Real Estate Capital LLC 4.48 % 41,000 26,642 08/05/27  Port Imperial South 4/5 Garage American General Life & A/G PC 4.85 % 32,600 32,600 12/01/29   Principal balance outstanding 1,426,111 896,055  Unamortized deferred financing costs (7,976) (7,470)   Total mortgages, loans payable and other obligations, net $ 1,418,135 $ 888,585      (a) Reflects effective rate of debt, including deferred financing costs, comprised of the cost of terminated treasury lock agreements (if any), debt initiation costs,  mark-to-market adjustment of acquired debt and other transaction costs, as applicable.  (b) The Company owned a 50 percent tenants-in-common interest in the Curtis Center property. On September 29, 2017, the Company sold its equity interest to  its joint venture partner, which included the retirement of this $75 million loan balance.  (c) The Chase II construction loan was paid off on December 5, 2017 using the proceeds of a new combined mortgage loan secured by The Chase at Overlook Ridge  and Chase II.  (d) This construction loan has a maximum borrowing capacity of $94 million and provides, subject to certain conditions, two one -year extension options with a fee  of 20 basis points for each year. See Note 12: Commitments and Contingencies - Construction Projects.  (e) On January 8, 2018, the Company prepaid this loan in full upon payment of a fee of approximately $8.4 million using borrowings from the Company's  unsecured revolving credit facility.  (f) Mortgage is collateralized by the three properties comprising One River Center.  (g) This construction loan has a maximum borrowing capacity of $42 million and provides, subject to certain conditions, a one -year extension option with a fee  of 25 basis points. See Note 12: Commitments and Contingencies - Construction Projects.  (h) This construction loan has a maximum borrowing capacity of $73 million and provides, subject to certain conditions, two one -year extension options with a fee  of 15 basis points each year. See Note 12: Commitments and Contingencies - Construction Projects.  (i) This construction loan has a maximum borrowing capacity of $78 million and provides, subject to certain conditions, two one -year extension options with a fee  of 15 basis points each year. See Note 12: Commitments and Contingencies - Construction Projects.  (j) This construction loan has a maximum borrowing capacity of $58 million and provides, subject to certain conditions, two one -year extension options with a fee  of 15 basis points each year. See Note 12: Commitments and Contingencies - Construction Projects.  (k) This mortgage loan, which includes unamortized fair value adjustment of $5.0 million as of December 31, 2017, was assumed by the  Company in April 2017 with the consolidation of all the interests in Monaco Towers. See Note 3: Recent Transactions - Consolidations.  (l) This mortgage loan was obtained by the Company in March 2017 to partially fund the acquisition of the Short Hills/Madison portfolio. 
Schedule Of Principal Payments	   Scheduled Principal  Period Amortization Maturities Total  2018 (a) $ 6,977 $ 275,210 $ 282,187  2019 665 576,489 577,154  2020 2,903 325,000 327,903  2021 3,227 318,800 322,027  2022 3,284 300,000 303,284  Thereafter 10,642 997,927 1,008,569  Sub-total 27,698 2,793,426 2,821,124  Adjustment for unamortized debt  discount/premium, net  December 31, 2017 (3,505) - (3,505)  Unamortized mark to market 4,987 - 4,987  Unamortized deferred financing costs (13,038) (13,038)   Totals/Weighted Average $ 16,142 $ 2,793,426 $ 2,809,568  (a) Includes a mortgage payable amount of approximately $209 million that the Company prepaid in January 2018.

Commitments And Contingencies (

Commitments And Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments And Contingencies Disclosure [Line Items]
Future Minimum Rental Payments Of Ground Leases	   Year Amount  2018 $ 2,465  2019 2,471  2020 2,487  2021 2,487  2022 2,487  2023 through 2084 212,534   Total $ 224,931 
Mack-Cali Realty LP [Member]
Commitments And Contingencies Disclosure [Line Items]
Future Minimum Rental Payments Of Ground Leases	   Year Amount  2018 $ 2,465  2019 2,471  2020 2,487  2021 2,487  2022 2,487  2023 through 2084 212,534   Total $ 224,931 

Tenant Leases (Tables)

Tenant Leases (Tables)	12 Months Ended
	Dec. 31, 2017
Leases [Line Items]
Future Minimum Rentals To Be Received Under Non-Cancelable Operating Leases	   Year Amount  2018 $ 362,261  2019 328,399  2020 296,227  2021 265,393  2022 237,020  2023 and thereafter 951,264   Total $ 2,440,564 
Mack-Cali Realty LP [Member]
Leases [Line Items]
Future Minimum Rentals To Be Received Under Non-Cancelable Operating Leases	   Year Amount  2018 $ 362,261  2019 328,399  2020 296,227  2021 265,393  2022 237,020  2023 and thereafter 951,264   Total $ 2,440,564 

Redeemable Noncontrolling Int40

Redeemable Noncontrolling Interests (Tables)	12 Months Ended
	Dec. 31, 2017
Redeemable Noncontrolling Interest [Line Items]
Schedule Of Changes In The Value Of The Redeemable Noncontrolling Interests	   Series A and Total  A-1 Preferred Rockpoint Redeemable  Units Interests Noncontrolling  In MCRLP in RRT Interests  Balance January 1, 2017 $ - $ - $ -  Redeemable Noncontrolling Interests Issued 52,013 150,000 202,013  Issuance Costs (464) (10,563) (11,027)  Net 51,549 139,437 190,986  Income Attributed to Noncontrolling Interests 1,631 7,209 8,840  Distributions (1,631) (7,209) (8,840)  Redemption Value Adjustment 775 20,447 21,222  Redeemable noncontrolling interests as of December 31, 2017 $ 52,324 $ 159,884 $ 212,208 
Mack-Cali Realty LP [Member]
Redeemable Noncontrolling Interest [Line Items]
Schedule Of Changes In The Value Of The Redeemable Noncontrolling Interests	   Series A and Total  A-1 Preferred Rockpoint Redeemable  Units Interests Noncontrolling  In MCRLP in RRT Interests  Balance January 1, 2017 $ - $ - $ -  Redeemable Noncontrolling Interests Issued 52,013 150,000 202,013  Issuance Costs (464) (10,563) (11,027)  Net 51,549 139,437 190,986  Income Attributed to Noncontrolling Interests 1,631 7,209 8,840  Distributions (1,631) (7,209) (8,840)  Redemption Value Adjustment 775 20,447 21,222  Redeemable noncontrolling interests as of December 31, 2017 $ 52,324 $ 159,884 $ 212,208 

Mack-Cali Realty Corporation 41

Mack-Cali Realty Corporation Stockholders' Equity And Mack-Cali Realty, L.P.'s Partners' Capital (Tables)	12 Months Ended
	Dec. 31, 2017
Stockolders Equity [Line Items]
Schedule Of Stock Option Plans	   Weighted Aggregate  Average Intrinsic  Shares Exercise Value  Under Options Price $(000’s)  Outstanding at January 1, 2015 10,000 $ 33.36 $ -  Granted 800,000 17.31  Lapsed or Cancelled (5,000) 45.47  Outstanding at December 31, 2015 ($17.31 – $21.25) 805,000 $ 17.33 4,843  Lapsed or Cancelled (5,000) 21.25  Outstanding at December 31, 2016 ($17.31) 800,000 $ 17.31 9,368  Granted, Lapsed or Cancelled - -  Outstanding at December 31, 2017 ($17.31) 800,000 $ 17.31 $ 3,400  Options exercisable at December 31, 2017 666,666  Available for grant at December 31, 2017 2,069,064 
Schedule Of Weighted Average Assumptions	   2015  Time Vesting Price Vesting  Options Options  Expected life (in years) 6.0 5.8  Risk-free interest rate 2.04 % 1.96 %  Volatility 29.0 % 29.0 %  Dividend yield 3.5 % 3.5 % 
Schedule Of Restricted Stock Awards	   Weighted-Average  Grant – Date  Shares Fair Value  Outstanding at January 1, 2015 346,946 $ 21.09  Granted (a) 41,337 17.51  Vested (250,132) 21.44  Forfeited (1,931) 20.31  Outstanding at December 31, 2015 136,220 $ 19.36  Granted 74,622 23.79  Vested (61,654) 18.94  Forfeited (3,910) 21.58  Outstanding at December 31, 2016 145,278 $ 21.76  Granted 59,985 27.00  Vested (95,009) 20.73  Forfeited (1,936) 25.83  Outstanding at December 31, 2017 108,318 $ 25.49  ( a ) Included in the 41,337 Restricted Stock Awards granted in 2015 were 37,551 awards granted to the Company’s two executive officers, Mitchell E. Rudin and Michael J. DeMarco.
Schedule Of Reconciliation Of Shares Used In Basic EPS Calculation To Shares Used In Diluted EPS Calculation	  Year Ended December 31,  Computation of Basic EPS 2017 2016 2015  Net income (loss) $ 33,718 $ 130,294 $ (142,052)  Add: Noncontrolling interest in consolidated joint ventures 1,018 651 1,044  Add (deduct): Noncontrolling interest in Operating Partnership (2,711) (13,721) 15,256  Deduct: Redeemable noncontrolling interest (8,840) - -  Deduct: Redemption value adjustment of redeemable noncontrolling  interests attributable to common shareholders (17,951) - -  Net income (loss) available to common shareholders for basic earnings per share $ 5,234 $ 117,224 $ (125,752)   Weighted average common shares 90,005 89,746 89,291   Basic EPS :  Net income (loss) available to common shareholders $ 0.06 $ 1.31 $ (1.41)         Year Ended December 31,  Computation of Diluted EPS 2017 2016 2015  Net income (loss) available to common shareholders for basic earnings per share $ 5,234 $ 117,224 $ (125,752)  Add (deduct): Noncontrolling interest in Operating Partnership 2,711 13,721 (15,256)  Deduct: Redemption value adjustment of redeemable noncontrolling  interests attributable to the Operating Partnership unitholders (2,074) - -  Net income (loss) for diluted earnings per share $ 5,871 $ 130,945 $ (141,008)   Weighted average common shares 100,703 100,498 100,222   Diluted EPS :  Net income (loss) available to common shareholders $ 0.06 $ 1.30 $ (1.41)   The following schedule reconciles the weighted average shares used in the basic EPS calculation to the shares used in the diluted EPS calculation: (in thousands)   Year Ended December 31,  2017 2016 2015  Basic EPS shares 90,005 89,746 89,291  Add: Operating Partnership – common units 10,405 10,499 10,931  Restricted Stock Awards 40 43 -  Stock Options 253 210 -  Diluted EPS Shares 100,703 100,498 100,222 
Mack-Cali Realty LP [Member]
Stockolders Equity [Line Items]
Schedule Of Stock Option Plans	   Weighted Aggregate  Average Intrinsic  Shares Exercise Value  Under Options Price $(000’s)  Outstanding at January 1, 2015 10,000 $ 33.36 $ -  Granted 800,000 17.31  Lapsed or Cancelled (5,000) 45.47  Outstanding at December 31, 2015 ($17.31 – $21.25) 805,000 $ 17.33 4,843  Lapsed or Cancelled (5,000) 21.25  Outstanding at December 31, 2016 ($17.31) 800,000 $ 17.31 9,368  Granted, Lapsed or Cancelled - -  Outstanding at December 31, 2017 ($17.31) 800,000 $ 17.31 $ 3,400  Options exercisable at December 31, 2017 666,666  Available for grant at December 31, 2017 2,069,064 
Schedule Of Weighted Average Assumptions	   2015  Time Vesting Price Vesting  Options Options  Expected life (in years) 6.0 5.8  Risk-free interest rate 2.04 % 1.96 %  Volatility 29.0 % 29.0 %  Dividend yield 3.5 % 3.5 % 
Schedule Of Restricted Stock Awards	   Weighted-Average  Grant – Date  Shares Fair Value  Outstanding at January 1, 2015 346,946 $ 21.09  Granted (a) 41,337 17.51  Vested (250,132) 21.44  Forfeited (1,931) 20.31  Outstanding at December 31, 2015 136,220 $ 19.36  Granted 74,622 23.79  Vested (61,654) 18.94  Forfeited (3,910) 21.58  Outstanding at December 31, 2016 145,278 $ 21.76  Granted 59,985 27.00  Vested (95,009) 20.73  Forfeited (1,936) 25.83  Outstanding at December 31, 2017 108,318 $ 25.49  ( a ) Included in the 41,337 Restricted Stock Awards granted in 2015 were 37,551 awards granted to the Company’s two executive officers, Mitchell E. Rudin and Michael J. DeMarco.
Schedule Of Reconciliation Of Shares Used In Basic EPS Calculation To Shares Used In Diluted EPS Calculation	  Year Ended December 31,  Computation of Basic EPU 2017 2016 2015  Net income (loss) $ 33,718 $ 130,294 $ (142,052)  Add: Noncontrolling interest in consolidated joint ventures 1,018 651 1,044  Deduct: Redeemable noncontrolling interest (8,840) - -  Deduct: Redemption value adjustment of redeemable noncontrolling interests (20,025) - -  Net income (loss) available to common unitholders for basic earnings per unit $ 5,871 $ 130,945 $ (141,008)   Weighted average common units 100,410 100,245 100,222   Basic EPU :  Net income (loss) available to common unitholders for basic earnings per unit $ 0.06 $ 1.31 $ (1.41)    Year Ended December 31,  Computation of Diluted EPU 2017 2016 2015  Net income (loss) available to common unitholders for basic earnings per unit $ 5,871 $ 130,945 $ (141,008)   Weighted average common unit 100,703 100,498 100,222   Diluted EPU :  Net income (loss) available to common unitholders for basic earnings per unit $ 0.06 $ 1.30 $ (1.41)  The following schedule reconciles the weighted average units used in the basic EPU calculation to the units used in the diluted EPU calculation: (in thousands)    Year Ended December 31,  2017 2016 2015  Basic EPU units 100,410 100,245 100,222  Add: Restricted Stock Awards 40 43 -  Stock Options 253 210 -  Diluted EPU Units 100,703 100,498 100,222 

Noncontrolling Interests In S42

Noncontrolling Interests In Subsidiaries (Tables)	12 Months Ended
	Dec. 31, 2017
Noncontrolling Interests In Subsidiaries [Abstract]
Changes In Noncontrolling Interests Of Subsidiaries	   Common LTIP  Units Units  Balance at January 1, 2015 11,083,876 -  Redemption of common units for shares of common stock (567,032) -  Balance at December 31, 2015 10,516,844 -  Redemption of common units for shares of common stock (28,739) -  Issuance of units - 657,373  Balance at December 31, 2016 10,488,105 657,373  Redemption of common units for shares of common stock (148,662) -  Issuance of units 99,412 578,323  Cancellation of units - (4,819)   Balance at December 31, 2017 10,438,855 1,230,877 

Segment Reporting (Tables)

Segment Reporting (Tables)	12 Months Ended
	Dec. 31, 2017
Segment Reporting Information [Line Items]
Schedule Of Selected Results Of Operations And Asset Information	  Commercial Multi-family Corporate Total  & Other Real Estate Real Estate & Services (d) & Other (e) Company  Total revenues:  2017 $ 522,223 $ 90,654 $ 3,323 $ 616,200  2016 541,271 69,873 2,254 613,398  2015 534,549 57,293 3,041 594,883   Total operating and  interest expenses (a):  2017 $ 238,055 $ 63,589 $ 94,662 $ 396,306  2016 263,663 60,646 91,042 415,351  2015 262,768 52,018 110,365 425,151   Equity in earnings (loss) of  unconsolidated joint ventures:  2017 $ 1,644 $ (7,725) $ - $ (6,081)  2016 23,796 (5,008) - 18,788  2015 5,118 (8,290) - (3,172)  -  Net operating income (loss) (b):  2017 $ 285,812 $ 19,340 $ (91,339) $ 213,813  2016 301,404 4,219 (88,788) 216,835  2015 276,899 (3,015) (107,324) 166,560   Total assets:  2017 $ 2,915,646 $ 1,937,708 $ 104,531 $ 4,957,885  2016 2,947,400 1,287,824 61,542 4,296,766   Total long-lived assets (c):  2017 $ 2,613,815 $ 1,645,410 $ 31,901 $ 4,291,126  2016 2,621,467 994,484 583 3,616,534   Total investments in  unconsolidated joint ventures:  2017 $ 15,143 $ 237,321 $ 162 $ 252,626  2016 81,549 238,498 - 320,047   (a) Total operating and interest expenses represent the sum of: real estate taxes; utilities; operating services; real estate services expenses; general and administrative , acquisition-related costs and interest expense (net of interest income). All interest expense, net of interest and other investment income, (including for property-level mortgages) is excluded from segment amounts and classified in Corporate & Other for all periods. (b) Net operating income represents total revenues less total operating and interest expenses (as defined in Note “a”), plus equity in earnings (loss) of unconsolidated joint ventures, for the period. (c) Long-lived assets are comprised of net investment in rental property, unbilled rents receivable and goodwill. (d) Segment assets and operations were owned through a consolidated variable interest entity commencing in February 2017. (e) Corporate & Other represents all corporate-level items (including interest and other investment income, interest expense, non-property general and administrative expense) as well as intercompany eliminations necessary to reconcile to consolidated Company totals.
Schedule Of Reconciliation Of Net Operating Income To Net Income Available To Common Shareholders	   Year Ended December 31,  2017 2016 2015  Net operating income $ 213,813 $ 216,835 $ 166,560  Add (deduct):  Depreciation and amortization (205,169) (186,684) (170,402)  Gain on change of control of interests - 15,347 -  Realized gains (losses) and unrealized losses on disposition of  rental property, net 2,364 109,666 53,261  Gain on sale of investment in unconsolidated joint venture 23,131 5,670 6,448  Loss from extinguishment of debt, net (421) (30,540) -  Impairments - - (197,919)  Net income (loss) 33,718 130,294 (142,052)  Noncontrolling interest in consolidated joint ventures 1,018 651 1,044  Noncontrolling interest in Operating Partnership (2,711) (13,721) 15,256  Redeemable noncontrolling interest (8,840) - -  Net income (loss) available to common shareholders $ 23,185 $ 117,224 $ (125,752) 
Mack-Cali Realty LP [Member]
Segment Reporting Information [Line Items]
Schedule Of Selected Results Of Operations And Asset Information	  Commercial Multi-family Corporate Total  & Other Real Estate Real Estate & Services (d) & Other (e) Company  Total revenues:  2017 $ 522,223 $ 90,654 $ 3,323 $ 616,200  2016 541,271 69,873 2,254 613,398  2015 534,549 57,293 3,041 594,883   Total operating and  interest expenses (a):  2017 $ 238,055 $ 63,589 $ 94,662 $ 396,306  2016 263,663 60,646 91,042 415,351  2015 262,768 52,018 110,365 425,151   Equity in earnings (loss) of  unconsolidated joint ventures:  2017 $ 1,644 $ (7,725) $ - $ (6,081)  2016 23,796 (5,008) - 18,788  2015 5,118 (8,290) - (3,172)  -  Net operating income (loss) (b):  2017 $ 285,812 $ 19,340 $ (91,339) $ 213,813  2016 301,404 4,219 (88,788) 216,835  2015 276,899 (3,015) (107,324) 166,560   Total assets:  2017 $ 2,915,646 $ 1,937,708 $ 104,531 $ 4,957,885  2016 2,947,400 1,287,824 61,542 4,296,766   Total long-lived assets (c):  2017 $ 2,613,815 $ 1,645,410 $ 31,901 $ 4,291,126  2016 2,621,467 994,484 583 3,616,534   Total investments in  unconsolidated joint ventures:  2017 $ 15,143 $ 237,321 $ 162 $ 252,626  2016 81,549 238,498 - 320,047   (a) Total operating and interest expenses represent the sum of: real estate taxes; utilities; operating services; real estate services expenses; general and administrative , acquisition-related costs and interest expense (net of interest income). All interest expense, net of interest and other investment income, (including for property-level mortgages) is excluded from segment amounts and classified in Corporate & Other for all periods. (b) Net operating income represents total revenues less total operating and interest expenses (as defined in Note “a”), plus equity in earnings (loss) of unconsolidated joint ventures, for the period. (c) Long-lived assets are comprised of net investment in rental property, unbilled rents receivable and goodwill. (d) Segment assets and operations were owned through a consolidated variable interest entity commencing in February 2017. (e) Corporate & Other represents all corporate-level items (including interest and other investment income, interest expense, non-property general and administrative expense) as well as intercompany eliminations necessary to reconcile to consolidated Company totals.
Schedule Of Reconciliation Of Net Operating Income To Net Income Available To Common Shareholders	   Year Ended December 31,  2017 2016 2015  Net operating income $ 213,813 $ 216,835 $ 166,560  Add (deduct):  Depreciation and amortization (205,169) (186,684) (170,402)  Gain on change of control of interests - 15,347 -  Realized gains (losses) and unrealized losses on disposition of  rental property, net 2,364 109,666 53,261  Gain on sale of investment in unconsolidated joint venture 23,131 5,670 6,448  Loss from extinguishment of debt, net (421) (30,540) -  Impairments - - (197,919)  Net income (loss) 33,718 130,294 (142,052)  Noncontrolling interest in consolidated joint ventures 1,018 651 1,044  Redeemable noncontrolling interest (8,840) -  Net income (loss) available to common unitholders $ 25,896 $ 130,945 $ (141,008) 

Condensed Quarterly Financial44

Condensed Quarterly Financial Information (Tables)	12 Months Ended
	Dec. 31, 2017
Summary Of Condensed Quarterly Financial Information	  Quarter Ended 2017 December 31 September 30 June 30 March 31  Total revenues $ 143,529 $ 160,018 $ 162,766 $ 149,887  Net income (loss) $ 5,411 $ 44,703 $ (39,125) $ 22,729  Net income (loss) available to common shareholders $ 2,582 $ 38,054 $ (37,330) $ 19,879  `  Basic earnings per common share:  Net income (loss) available to common shareholders $ (0.01) $ 0.39 $ (0.44) $ 0.11   Diluted earnings per common share:  Net income (loss) available to common shareholders $ (0.01) $ 0.39 $ (0.44) $ 0.11       Quarter Ended 2016 December 31 September 30 June 30 March 31  Total revenues $ 153,731 $ 157,517 $ 149,227 $ 152,923  Net income (loss) $ 16,764 $ (9,605) $ 54,366 $ 68,769  Net income (loss) available to common shareholders $ 15,181 $ (8,541) $ 48,393 $ 62,191   Basic earnings per common share:  Net income (loss) available to common shareholders $ 0.17 $ (0.10) $ 0.54 $ 0.69   Diluted earnings per common share:  Net income (loss) available to common shareholders $ 0.17 $ (0.10) $ 0.54 $ 0.69
Mack-Cali Realty LP [Member]
Summary Of Condensed Quarterly Financial Information	  Quarter Ended 2017 December 31 September 30 June 30 March 31  Total revenues $ 143,529 $ 160,018 $ 162,766 $ 149,887  Net income (loss) $ 5,411 $ 44,703 $ (39,125) $ 22,729  Net income (loss) available to common unitholders $ 2,881 $ 42,467 $ (41,626) $ 22,174   Basic earnings per common unit:  Net income (loss) available to common unitholders $ (0.01) $ 0.39 $ (0.44) $ 0.11   Diluted earnings per common units:  Net income (loss) available to common unitolders $ (0.01) $ 0.39 $ (0.44) $ 0.11       Quarter Ended 2016 December 31 September 30 June 30 March 31  Total revenues $ 153,731 $ 157,517 $ 149,227 $ 152,923  Net income (loss) $ 16,764 $ (9,605) $ 54,366 $ 68,769  Net income (loss) available to common unitholders $ 16,955 $ (9,540) $ 54,055 $ 69,475   Basic earnings per common unit:  Net income (loss) available to common unitholders $ 0.17 $ (0.10) $ 0.54 $ 0.69   Diluted earnings per common unit:  Net income (loss) available to common unitholders $ 0.17 $ (0.10) $ 0.54 $ 0.69 

Organization And Basis Of Pre45

Organization And Basis Of Presentation (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)ft²statepropertyitem	Dec. 31, 2016USD ($)
Real Estate Properties [Line Items]
Percentage of ownership interest	89.60%	89.50%
Number of properties owned or investment interests	157
Aggregate square feet of the property owned or investment interest | ft²	17,700,000
Number of states where properties are located | state	6
Consolidated joint ventures, total real estate assets | $	$ 215.5	$ 201.9
Consolidated joint ventures, mortgages | $	81.2	78.4
Consolidated joint ventures, other liabilities | $	$ 19.3	$ 19.2
Commercial Properties [Member]
Real Estate Properties [Line Items]
Number of tenants | item	900
Multi-Family Properties [Member]
Real Estate Properties [Line Items]
Number of properties owned or investment interests	18
Number of units | item	5,826
Office And Office/Flex Buildings [Member]
Real Estate Properties [Line Items]
Number of properties owned or investment interests	56
Aggregate square feet of the property owned or investment interest | ft²	3,100,000
Office [Member]
Real Estate Properties [Line Items]
Number of properties owned or investment interests	69
Aggregate square feet of the property owned or investment interest | ft²	14,100,000
Flex Properties [Member]
Real Estate Properties [Line Items]
Number of properties owned or investment interests	70
Unconsolidated Joint Venture Office Buildings [Member]
Real Estate Properties [Line Items]
Number of properties owned or investment interests	4
Aggregate square feet of the property owned or investment interest | ft²	500,000
Industrial/Warehouse Facilities [Member]
Real Estate Properties [Line Items]
Number of properties owned or investment interests	6
Aggregate square feet of the property owned or investment interest | ft²	387,400
Unconsolidated Joint Venture Multi-Family Properties [Member]
Real Estate Properties [Line Items]
Number of properties owned or investment interests	8
Number of units | item	3,275
Unconsolidated Joint Venture Office/Flex Buildings And Hotel [Member]
Real Estate Properties [Line Items]
Number of properties owned or investment interests	1
Parking/Retail [Member]
Real Estate Properties [Line Items]
Number of properties owned or investment interests	6
Aggregate square feet of the property owned or investment interest | ft²	137,100
Unconsolidated Joint Venture Parking/Retail Buildings [Member]
Real Estate Properties [Line Items]
Number of properties owned or investment interests	2
Aggregate square feet of the property owned or investment interest | ft²	81,700
Land [Member]
Real Estate Properties [Line Items]
Number of properties owned or investment interests	1

Significant Accounting Polici46

Significant Accounting Policies (Narrative) (Details) - USD ($)	3 Months Ended		12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 03, 2018	Jan. 05, 2017	Dec. 31, 2014
Significant Accounting Policies [Line Items]
Capitalized development and construction salaries and other related costs			$ 2,200,000	$ 2,600,000	$ 4,200,000
Construction, tenant improvement, and development in-progress	$ 559,500,000	$ 361,100,000	$ 559,500,000	361,100,000
Maximum period after cessation of major construction activity that projects are considered complete			1 year
Threshold of investment value for discontinuation of equity method accounting	0		$ 0
Amortization of deferred financing costs			4,612,000	4,582,000	3,790,000
Loss from extinguishment of debt, net			(421,000)	12,420,000
Write off of unamortized deferred financing costs			400,000	700,000	0
Deferred leasing costs			3,146,000	3,270,000	3,521,000
Difference between the estimated net basis and net assets of the rental property for federal income tax purposes	231,067,000		231,067,000
Taxable income			97,037,000	$ 30,208,000	$ 63,285,000
Deferred tax asset	$ 11,700,000		11,700,000
Income taxes, material adjustment amount			$ 0
Common stock, shares outstanding	89,914,113	89,696,713	89,914,113	89,696,713			89,696,824
Common units outstanding	10,438,855	10,488,105	10,438,855	10,488,105	10,516,844		10,488,105	11,083,876
LTIP units outstanding	1,230,877	657,373	1,230,877	657,373			657,373
Distributions payable, record date	Jan. 3, 2018	Jan. 5, 2017
Distributions payable, approved date	Dec. 12, 2017	Dec. 13, 2016
Common stock dividends and common unit distributions per share	$ 0.20	$ 0.15
Dividends paid per common share			$ 0.70	$ 0.60	$ 0.60
Dividends paid, percent representing ordinary income					90.00%
Dividends paid, percent representing return of capital to shareholders				100.00%	10.00%
Dividends paid, percent representing capital gain			100.00%
Restricted stock expense			$ 7,447,000	$ 5,646,000	$ 2,219,000
Distributions payable, pay date	Jan. 12, 2018	Jan. 13, 2017
Increase (decrease) to deferred tax assets			(5,300,000)
Increase (decrease) to valuation allowance			$ (5,300,000)
Subsequent Event [Member]
Significant Accounting Policies [Line Items]
Common stock, shares outstanding						89,914,658
Common units outstanding						10,438,855
LTIP units outstanding						1,230,877

Significant Accounting Polici47

Significant Accounting Policies (Estimated Useful Lives Of Assets) (Details)	12 Months Ended
	Dec. 31, 2017
Minimum [Member] | Buildings And Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	5 years
Minimum [Member] | Furniture, Fixtures And Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	5 years
Maximum [Member] | Buildings And Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	40 years
Maximum [Member] | Furniture, Fixtures And Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	10 years

Recent Transactions (Acquisitio

Recent Transactions (Acquisitions) (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)property	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Real Estate Properties [Line Items]
Purchase price of property	$ 90,068	$ 121,582	$ 94,073
Jersey City, Morris Township And Red Bank, New Jersey [Member]
Real Estate Properties [Line Items]
Number of real estate properties | property	3
Purchase price of property	$ 80,000

Recent Transactions (Consolidat

Recent Transactions (Consolidations) (Narrative) (Details) $ in Thousands	Feb. 28, 2017USD ($)ft²itemshares	Feb. 03, 2017USD ($)shares	Jul. 08, 2016USD ($)	Jan. 19, 2016USD ($)	Jan. 05, 2016USD ($)item	Apr. 30, 2017USD ($)shares	Jun. 30, 2016USD ($)item	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Feb. 02, 2017
Real Estate Properties [Line Items]
Acquisition cost								$ 36,060	$ 35,930	$ 78,027
Consolidated joint ventures, total real estate assets								215,500	$ 201,900
Net assets acquired								$ 394,589
Percentage of ownership interest								89.60%	89.50%
Purchase price of property								$ 90,068	$ 121,582	94,073
Gain on sale of investment in unconsolidated joint venture								23,131	5,670	6,448
Mortgage loan carrying amount								45,734
Gain on change of control of interests									15,347
Series A-1 Units [Member]
Real Estate Properties [Line Items]
Percentage of ownership interest	29.00%
Mack-Cali Realty LP [Member]
Real Estate Properties [Line Items]
Acquisition cost								36,060	35,930	78,027
Purchase price of property								90,068	121,582	94,073
Gain on sale of investment in unconsolidated joint venture								$ 23,131	5,670	$ 6,448
Gain on change of control of interests									15,347
Mack-Cali Realty LP [Member] | Series A Units [Member]
Real Estate Properties [Line Items]
Preferred units shares issued | shares		42,800
Percentage of interest in venture		37.50%
Preferred unit annual rate		3.50%
Preferred units aggregate amount		$ 42,800
Mack-Cali Realty LP [Member] | Series A-1 Units [Member]
Real Estate Properties [Line Items]
Preferred units shares issued | shares	9,213					91
Percentage of interest in venture	13.80%
Preferred unit annual rate	3.50%
Overlook Ridge Apartments Investors, L.L.C. [Member]
Real Estate Properties [Line Items]
Percentage of interest in venture					50.00%
Loans assumed				$ 72,500	$ 52,700
Net assets acquired									52,035
Number of units | item					371
Purchase price of property					$ 39,800
Gain on sale of investment in unconsolidated joint venture									$ 10,200
Mortgage loan, maturity date									Feb. 1, 2023
Spread over LIBOR				3.625%
Portside Apartment Holdings, L.L.C. [Member]
Real Estate Properties [Line Items]
Percentage of interest in venture							38.25%
Net assets acquired									$ 44,827
Number of units | item							175
Purchase price of property							$ 39,600
Mortgage loan, maturity date								Aug. 1, 2023
Spread over LIBOR			3.44%
Mortgage loan carrying amount			$ 59,000				$ 42,500
Gain on change of control of interests									$ 5,200
Plaza VIII & IX Associates, L.L.C. [Member]
Real Estate Properties [Line Items]
Percentage of interest in venture											50.00%
Percentage of additional interest acquired		12.50%
Acquisition cost		$ 14,300
Consolidated joint ventures, total real estate assets		$ 60,600
Monaco [Member]
Real Estate Properties [Line Items]
Number of towers | item	2
Net assets acquired								$ 139,886
Garage Parking Spaces | item	558
Number of stories | item	50
Area of property (in square feet) | ft²	12,300
Number of units | item	523
Monaco [Member] | Series A-1 Units [Member]
Real Estate Properties [Line Items]
Percentage of interest in venture	13.80%
Monaco [Member] | Mack-Cali Realty LP [Member] | Series A-1 Units [Member]
Real Estate Properties [Line Items]
Preferred units shares issued | shares	9,122					91
Percentage of interest in venture						71.20%
Preferred units aggregate amount	$ 9,100
Acquisition cost						$ 130,900
Debt assumed						$ 171,200

Recent Transactions (Other Inve

Recent Transactions (Other Investments In 2016) (Narrative) (Details) $ in Thousands	Apr. 26, 2016USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)ft²item	Dec. 31, 2015USD ($)
Real Estate Properties [Line Items]
Purchase price of property | $		$ 90,068	$ 121,582	$ 94,073
Weehawken, New Jersey [Member]
Real Estate Properties [Line Items]
Purchase price of property | $	$ 36,400
Port Imperial 4/5 Garage And Retail [Member] | Projects Under Development And Developable Land [Member]
Real Estate Properties [Line Items]
Number of units | item			1,100
Area of property (in square feet) | ft²			290,000
Percentage of interest in venture			52.50%
Port Imperial South 11 [Member] | Weehawken, New Jersey [Member]
Real Estate Properties [Line Items]
Number of units | item			295

Recent Transactions (Dispositio

Recent Transactions (Dispositions/Rental Property Held for Sale) (Narrative) (Details) $ in Thousands	1 Months Ended	2 Months Ended	12 Months Ended
	Feb. 28, 2018USD ($)	Feb. 28, 2017USD ($)	Dec. 31, 2017USD ($)ft²itemproperty	Dec. 31, 2016USD ($)ft²itemproperty
Disposal Group, Held-for-sale, Not Discontinued Operations [Member]
Real Estate Properties [Line Items]
Assets held for sale, Deferred charges and other assets				$ 1,700
Assets held for sale, Unbilled rents receivable, net				1,200
Assets held for sale, Accounts payable, accrued expenses and other liabilities				1,100
Assets held for sale, Rents received in advance and security deposits				1,900
Expected assets to be written off				2,900
Expected liabilities to be written off				$ 500
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Three Office Properties Disposed [Member]
Real Estate Properties [Line Items]
Sales proceeds		$ 45,800
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Office [Member]
Real Estate Properties [Line Items]
Area of property (in square feet) | ft²				750,000
Number of properties held for sale | property				8
Estimated expected sales proceeds				$ 49,000
Disposal Group, Not Discontinued Operations [Member]
Real Estate Properties [Line Items]
Unrealized losses on rental properties held for sale			$ (12,331)	(7,665)
Sales proceeds			$ 399,332	$ 664,481
Number of properties sold | item			60	30
Parsippany, Paramus, Rochelle Park, Hamilton And Wall, New Jersey And White Plains, New York [Member] | Disposal Group, Held-for-sale, Not Discontinued Operations [Member]
Real Estate Properties [Line Items]
Assets held for sale, Deferred charges and other assets			$ 9,800
Assets held for sale, Unbilled rents receivable, net			4,700
Assets held for sale, Accounts payable, accrued expenses and other liabilities			4,600
Expected assets to be written off			13,400
Expected liabilities to be written off			$ 300
Parsippany, Paramus, Rochelle Park, Hamilton And Wall, New Jersey And White Plains, New York [Member] | Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Office [Member]
Real Estate Properties [Line Items]
Area of property (in square feet) | ft²			2,000,000
Number of properties held for sale | property			21
Estimated expected sales proceeds			$ 223,000
Number of properties not epected to recover from estimated net sales proceeds | property			7
Parsippany, Paramus, Rochelle Park, Hamilton And Wall, New Jersey And White Plains, New York [Member] | Disposal Group, Not Discontinued Operations [Member] | Office [Member] | Subsequent Event [Member]
Real Estate Properties [Line Items]
Sales proceeds	$ 25,900

Recent Transactions (Rockpoint

Recent Transactions (Rockpoint Transaction) (Narrative) (Details) - USD ($) $ in Thousands	Mar. 10, 2017	Feb. 27, 2017	Dec. 31, 2017	Dec. 31, 2016
Preferred Units [Line Items]
Assets			$ 1,139,322	$ 2,024,522
Mortgages and loans payable			689,412	1,350,973
Other liabilities			80,746	247,212
RRLP [Member]
Preferred Units [Line Items]
Assets			1,900,000	1,300,000
Mortgages and loans payable			769,700	480,700
Other liabilities			95,900	$ 40,100
Investment Agreement [Member] | Rockpoint [Member]
Preferred Units [Line Items]
Incremental closing payments, Limited Partnership interest	$ 150,000
Investment Agreement [Member] | Rockpoint [Member] | Minimum [Member]
Preferred Units [Line Items]
Incremental closing payments, Limited Partnership interest			$ 10,000
Investment Agreement [Member] | Rockpoint [Member] | Maximum [Member]
Preferred Units [Line Items]
Contributed amount to obtain equity units		$ 300,000

Recent Transactions (Unconsolid

Recent Transactions (Unconsolidated Joint Venture Activity) (Narrative) (Details) $ in Thousands

Sep. 29, 2017USD ($)

Sep. 21, 2017USD ($)

Feb. 15, 2017USD ($)

Jan. 31, 2017USD ($)

May 26, 2016USD ($)item

Apr. 01, 2016

Oct. 31, 2016

Mar. 31, 2016

Dec. 31, 2017USD ($)item

Dec. 31, 2016USD ($)

Dec. 31, 2015USD ($)

Real Estate Properties [Line Items]

Gain (loss) on sale of investment in unconsolidated joint venture

$ 23,131

$ 5,670

$ 6,448

Proceeds from the sale of investments in unconsolidated joint ventures

110,269

6,420

6,448

Investment in unconsolidated joint ventures

36,060

$ 35,930

$ 78,027

Debt

$ 2,809,568

Unconsolidated Joint Venture Multi-Family Properties [Member]

Real Estate Properties [Line Items]

Number of units | item

3,275

Multi-Family Properties [Member]

Real Estate Properties [Line Items]

Number of units | item

5,826

PruRose Riverwalk G, L.L.C. [Member]

Real Estate Properties [Line Items]

Percent of pari passu interest

22.50%

Percentage of additional interest acquired

50.00%

25.00%

Number of units | item

316

PruRose Port Imperial South 15, L.L.C. [Member]

Real Estate Properties [Line Items]

Number of units | item

236

PruRose Port Imperial South 13, L.L.C. [Member] | Multi-Family Properties [Member]

Real Estate Properties [Line Items]

Number of units | item

280

Pru Rose Port Imperial South 15 L.L.C. And Pru Rose Port Imperial South 13 L.L.C. [Member]

Real Estate Properties [Line Items]

Gain (loss) on sale of investment in unconsolidated joint venture

$ 5,700

Proceeds from the sale of investments in unconsolidated joint ventures

$ 6,400

KPG-P 100 IMW JV, LLC, Keystone-Penn And Keystone-Tristate [Member]

Real Estate Properties [Line Items]

Gain (loss) on sale of investment in unconsolidated joint venture

$ 7,400

Proceeds from the sale of investments in unconsolidated joint ventures

$ 9,700

Elmajo Urban Renewal Associates, LLC And Estuary Urban Renewal Associates, LLC [Member] | Unconsolidated Joint Venture Multi-Family Properties [Member]

Real Estate Properties [Line Items]

Gain (loss) on sale of investment in unconsolidated joint venture

$ 5,100

Proceeds from the sale of investments in unconsolidated joint ventures

$ 5,100

Percentage of interest in venture

7.50%

RoseGarden Monaco, L.L.C. [Member]

Real Estate Properties [Line Items]

Gain (loss) on sale of investment in unconsolidated joint venture

$ (1,400)

RoseGarden Monaco, L.L.C. [Member] | Unconsolidated Joint Venture Multi-Family Properties [Member]

Real Estate Properties [Line Items]

Percentage of interest in venture

[1],[2]

41.67%

Number of units | item

[2]

250

KPG-MCG Curtis JV, LLC [Member]

Real Estate Properties [Line Items]

Gain (loss) on sale of investment in unconsolidated joint venture

$ 12,000

Proceeds from the sale of investments in unconsolidated joint ventures

102,500

Net sales proceeds held by qualified intermediary

$ 5,600

Debt

$ 75,000

[1]

Company's effective ownership % represents the Company's entitlement to residual distributions after payments of priority returns, where applicable.

[2]

On September 21, 2017, the joint venture agreement was terminated. Accordingly, the Company wrote off the carrying value of its investment in the joint venture and recorded a loss of $1.4 million on the disposition of its joint venture interest.

Recent Transactions (Schedule O

Recent Transactions (Schedule Of Properties Acquired) (Details)		12 Months Ended
		Dec. 31, 2017USD ($)ft²item	Dec. 31, 2016USD ($)ft²item
Business Acquisition [Line Items]
Number of Buildings, Acquired | item		9	5
Rentable Square Feet, Acquired | ft²		1,392,500	1,058,462
Acquisition Cost		$ 394,589,000	$ 326,811,000
Loan balance		$ 2,809,568,000	$ 2,340,009,000
11 Martine Avenue [Member]
Business Acquisition [Line Items]
Number of Buildings, Acquired | item	[1]		1
Rentable Square Feet, Acquired | ft²	[1]		82,000
Acquisition Cost	[1]		$ 10,750,000
Number of apartment units | item			4
Area of property (in square feet) | ft²			262,000
320, 321 University Avenue [Member]
Business Acquisition [Line Items]
Number of Buildings, Acquired | item	[2]		2
Rentable Square Feet, Acquired | ft²	[2]		147,406
Acquisition Cost	[2]		$ 23,000,000
101 Wood Avenue South [Member]
Business Acquisition [Line Items]
Number of Buildings, Acquired | item	[3]		1
Rentable Square Feet, Acquired | ft²	[3]		262,841
Acquisition Cost	[3]		$ 82,300,000
111 River Street [Member]
Business Acquisition [Line Items]
Number of Buildings, Acquired | item	[3]		1
Rentable Square Feet, Acquired | ft²	[3]		566,215
Acquisition Cost	[3]		$ 210,761,000
Red Bank Portfolio [Member]
Business Acquisition [Line Items]
Number of Buildings, Acquired | item	[4]	3
Rentable Square Feet, Acquired | ft²	[4]	279,472
Acquisition Cost	[4]	$ 27,228,000
Short Hills / Madison Portfolio [Member]
Business Acquisition [Line Items]
Number of Buildings, Acquired | item	[5]	6
Rentable Square Feet, Acquired | ft²	[5]	1,113,028
Acquisition Cost	[5]	$ 367,361,000
Unsecured Revolving Credit Facility [Member] | Short Hills / Madison Portfolio [Member]
Business Acquisition [Line Items]
Loan balance		$ 124,500,000
[1]	Acquisition represented four units of condominium interests which collectively comprise floors 2 through 5. Upon completion of the acquisition, the Company owns the entire 14-story 262,000 square-foot building. The acquisition was funded using available cash.
[2]	This acquisition was funded through borrowings under the Company's unsecured revolving credit facility.
[3]	This acquisition was funded using available cash and through borrowings under the Company's unsecured revolving credit facility.
[4]	This acquisition was funded through borrowings under the Company's unsecured revolving credit facility.
[5]	This acquisition was funded through borrowings under the Company's unsecured revolving credit facility and a new $124.5 million loan secured by three of the properties.

Recent Transactions (Schedule55

Recent Transactions (Schedule Of Purchase Price Allocation) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Land and leasehold interest		$ 38,250
Buildings and improvements and other assets		311,346
Above market leases	[1]	6,485
In-place lease values	[1]	48,775
Sub Total		404,856
Less: Below market lease values	[1]	(10,267)
Net assets recorded upon acquisition		$ 394,589
Above Market, In-Place And Below Market Leases [Member]
Business Acquisition [Line Items]
Amortization period		5 years 4 months 24 days	8 years 1 month 6 days
11 Martine Avenue [Member]
Business Acquisition [Line Items]
Land and leasehold interest			$ 2,460
Buildings and improvements and other assets			8,290
Net assets recorded upon acquisition			10,750
320, 321 University Avenue [Member]
Business Acquisition [Line Items]
Land and leasehold interest			7,305
Buildings and improvements and other assets			15,695
Net assets recorded upon acquisition			23,000
101 Wood Avenue South [Member]
Business Acquisition [Line Items]
Land and leasehold interest			8,509
Buildings and improvements and other assets			72,738
Above market leases	[2]		58
In-place lease values	[2]		6,743
Sub Total			88,048
Less: Below market lease values	[2]		(5,748)
Net assets recorded upon acquisition			82,300
111 River Street [Member]
Business Acquisition [Line Items]
Land and leasehold interest			204
Buildings and improvements and other assets			198,609
Above market leases	[2]		617
In-place lease values	[2]		43,801
Other assets			11,279
Sub Total			254,510
Less: Below market lease values	[2]		(43,749)
Net assets recorded upon acquisition			$ 210,761
Red Bank Portfolio [Member]
Business Acquisition [Line Items]
Land and leasehold interest		$ 7,914
Buildings and improvements and other assets		16,047
Above market leases	[1]	118
In-place lease values	[1]	3,171
Sub Total		27,250
Less: Below market lease values	[1]	(22)
Net assets recorded upon acquisition		27,228
Short Hills / Madison Portfolio [Member]
Business Acquisition [Line Items]
Land and leasehold interest		30,336
Buildings and improvements and other assets		295,299
Above market leases	[1]	6,367
In-place lease values	[1]	45,604
Sub Total		377,606
Less: Below market lease values	[1]	(10,245)
Net assets recorded upon acquisition		$ 367,361
[1]	Above market, in-place and below market leases are being amortized over a weighted-average term of 5.4 years.
[2]	Above market, in-place and below market leases are being amortized over a weighted-average term of 8.1 years

Recent Transactions (Schedule56

Recent Transactions (Schedule Of Properties Which Commenced Initial Operations) (Details) $ in Thousands		12 Months Ended
		Dec. 31, 2016USD ($)item	Dec. 31, 2017item
Unconsolidated Joint Venture Multi-Family Properties [Member]
Real Estate Properties [Line Items]
Number of Apartment Units | item			3,275
Quarry Place At Tuckahoe [Member] | Unconsolidated Joint Venture Multi-Family Properties [Member]
Real Estate Properties [Line Items]
Number of Apartment Units | item		108
Development Costs Incurred by Company	[1]	$ 56,961
The Chase II At Overlook Ridge [Member] | Unconsolidated Joint Venture Multi-Family Properties [Member]
Real Estate Properties [Line Items]
Number of Apartment Units | item		292
Development Costs Incurred by Company	[2]	$ 65,218
Quarry Place At Tuckahoe And The Chase II At Overlook Ridge [Member] | Unconsolidated Joint Venture Multi-Family Properties [Member]
Real Estate Properties [Line Items]
Number of Apartment Units | item		400
Development Costs Incurred by Company		$ 122,179
Land [Member] | Quarry Place At Tuckahoe [Member]
Real Estate Properties [Line Items]
Development Costs Incurred by Company		5,600
Land [Member] | The Chase II At Overlook Ridge [Member]
Real Estate Properties [Line Items]
Development Costs Incurred by Company		10,800
Construction Loan [Member] | The Chase II At Overlook Ridge [Member]
Real Estate Properties [Line Items]
Expected costs		$ 9,700
[1]	Development costs as of December 31, 2016 included approximately $5.6 million in land costs.
[2]	Development costs as of December 31, 2016 included approximately $10.8 million in land costs. As of December 31, 2016, the Company anticipates additional costs of approximately $9.7 million, which will be funded from a construction loan.

Recent Transactions (Schedule57

Recent Transactions (Schedule Of Net Assets Recorded Upon Consolidation) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Land and Leasehold Interests		$ 38,250
Buildings and improvements and other assets		311,346
Above market leases	[1]	6,485
In-place lease values	[1]	48,775
Less: Below market lease values	[1]	(10,267)
Sub Total		404,856
Net assets recorded upon acquisition		$ 394,589
In-Place And Below Market Leases [Member]
Business Acquisition [Line Items]
Amortization period			7 years 4 months 24 days
Above Market, In-Place And Below Market Leases [Member]
Business Acquisition [Line Items]
Amortization period		5 years 4 months 24 days	8 years 1 month 6 days
Overlook Ridge Apartments Investors, L.L.C. [Member]
Business Acquisition [Line Items]
Land and Leasehold Interests			$ 11,072
Buildings and improvements and other assets			87,793
Furniture, fixtures and equipment			1,695
Other assets			237
In-place lease values	[2]		4,389
Less: Below market lease values	[2]		(489)
Sub Total			104,697
Less: Debt assumed at fair value			(52,662)
Net assets recorded upon acquisition			52,035
Portside Apartment Holdings, L.L.C. [Member]
Business Acquisition [Line Items]
Buildings and improvements and other assets			73,713
Furniture, fixtures and equipment			1,038
Other assets			10,181
In-place lease values	[2]		2,637
Less: Below market lease values	[2]		(242)
Sub Total			87,327
Less: Debt assumed at fair value			(42,500)
Net assets recorded upon acquisition			$ 44,827
Monaco North [Member]
Business Acquisition [Line Items]
Land and Leasehold Interests		$ 27,300
Buildings and improvements and other assets		112,841
Above market leases	[3]	350
In-place lease values	[3]	4,585
Less: Below market lease values	[3]	(141)
Sub Total		144,935
Less: Debt assumed at fair value		(79,544)
Net assets recorded upon acquisition		65,391
Monaco South [Member]
Business Acquisition [Line Items]
Land and Leasehold Interests		31,461
Buildings and improvements and other assets		129,895
In-place lease values	[3]	4,913
Less: Below market lease values	[3]	(118)
Sub Total		166,151
Less: Debt assumed at fair value		(91,656)
Net assets recorded upon acquisition		74,495
Monaco [Member]
Business Acquisition [Line Items]
Land and Leasehold Interests		58,761
Buildings and improvements and other assets		242,736
Above market leases	[3]	350
In-place lease values	[3]	9,498
Less: Below market lease values	[3]	(259)
Sub Total		311,086
Less: Debt assumed at fair value		(171,200)
Net assets recorded upon acquisition		$ 139,886
Monaco [Member] | Above Market, In-Place And Below Market Leases [Member]
Business Acquisition [Line Items]
Amortization period		8 months
[1]	Above market, in-place and below market leases are being amortized over a weighted-average term of 5.4 years.
[2]	In-place lease values and below-market lease values are being amortized over a weighted average term of 7.4 months.
[3]	Above market, in-place and below market leases are being amortized over a weighted-average term of 8 months.

Recent Transactions (Schedule58

Recent Transactions (Schedule Of Dispositions/Rental Property Held For Sale) (Details) $ in Thousands		Jan. 11, 2017USD ($)	Dec. 31, 2017USD ($)ft²item	Dec. 31, 2016USD ($)item	Dec. 31, 2015USD ($)	Dec. 31, 2012USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
New mortgage loan			$ 44,695
Mortgage loan carrying amount			$ 45,734
Impairments					$ 197,919
Disposal Group, Not Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item			60	30
Rentable Square Feet, Disposed | ft²			4,677,058
Net Sales Proceeds			$ 399,332	$ 664,481
Net Carrying Value			384,637	547,150
Realized Gain (loss)/Unrealized Loss, net			14,695	117,331
Unrealized losses on rental properties held for sale			(12,331)	(7,665)
Totals			$ 2,364	109,666
Disposal Group, Not Discontinued Operations [Member] | Cranford Portfolio [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item			6
Rentable Square Feet, Disposed | ft²			435,976
Net Sales Proceeds			$ 26,598
Net Carrying Value			22,736
Realized Gain (loss)/Unrealized Loss, net			$ 3,862
Disposal Group, Not Discontinued Operations [Member] | 440 Route 22 East [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item	[1]		1
Rentable Square Feet, Disposed | ft²	[1]		198,376
Net Sales Proceeds	[1]		$ 10,074
Net Carrying Value	[1]		10,069
Realized Gain (loss)/Unrealized Loss, net	[1]		$ 5
Impairments				$ 7,700
Disposal Group, Not Discontinued Operations [Member] | 3 Independence Way [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item			1
Rentable Square Feet, Disposed | ft²			111,300
Net Sales Proceeds			$ 11,549
Net Carrying Value			9,910
Realized Gain (loss)/Unrealized Loss, net			$ 1,639
Disposal Group, Not Discontinued Operations [Member] | 103 Carnegie Center [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item			1
Rentable Square Feet, Disposed | ft²			96,000
Net Sales Proceeds			$ 15,063
Net Carrying Value			8,271
Realized Gain (loss)/Unrealized Loss, net			$ 6,792
Disposal Group, Not Discontinued Operations [Member] | 400 Chestnut Ridge Road [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item			1
Rentable Square Feet, Disposed | ft²			89,200
Net Sales Proceeds			$ 6,891
Net Carrying Value			7,498
Realized Gain (loss)/Unrealized Loss, net			$ (607)
Disposal Group, Not Discontinued Operations [Member] | 140 East Ridgewood Avenue [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item			1
Rentable Square Feet, Disposed | ft²			239,680
Net Sales Proceeds			$ 30,201
Net Carrying Value			30,737
Realized Gain (loss)/Unrealized Loss, net			$ (536)
Disposal Group, Not Discontinued Operations [Member] | Bergen Portfolio [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item			5
Rentable Square Feet, Disposed | ft²			1,061,544
Net Sales Proceeds	[2]		$ 86,973
Net Carrying Value			135,121
Realized Gain (loss)/Unrealized Loss, net			(48,148)
Disposal Group, Not Discontinued Operations [Member] | Bergen Portfolio [Member] | Buyer [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Notes receivable			$ 65,000
Disposal Group, Not Discontinued Operations [Member] | 377 Summerhill Road [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item			1
Rentable Square Feet, Disposed | ft²			40,000
Net Sales Proceeds			$ 3,221
Net Carrying Value			2,172
Realized Gain (loss)/Unrealized Loss, net			1,049
Disposal Group, Not Discontinued Operations [Member] | 700 Executive Boulevard [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net Sales Proceeds	[3]		5,717
Net Carrying Value	[3]		970
Realized Gain (loss)/Unrealized Loss, net	[3]		$ 4,747
Disposal Group, Not Discontinued Operations [Member] | Totowa Portfolio [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item			13
Rentable Square Feet, Disposed | ft²			499,243
Net Sales Proceeds			$ 63,624
Net Carrying Value			27,630
Realized Gain (loss)/Unrealized Loss, net			$ 35,994
Disposal Group, Not Discontinued Operations [Member] | 890 Mountain Avenue [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item	[4]		1
Rentable Square Feet, Disposed | ft²	[4]		80,000
Net Sales Proceeds	[4]		$ 4,852
Net Carrying Value	[4]		6,139
Realized Gain (loss)/Unrealized Loss, net	[4]		$ (1,287)
Impairments					7,000
Disposal Group, Not Discontinued Operations [Member] | 135 Chestnut Ridge Road [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item			1
Rentable Square Feet, Disposed | ft²			66,150
Net Sales Proceeds	[5]		$ 5,844
Net Carrying Value			2,929
Realized Gain (loss)/Unrealized Loss, net			2,915
Impairments					4,200
Net sales proceeds held by qualified intermediary			$ 5,900
Disposal Group, Not Discontinued Operations [Member] | Moorestown Portfolio [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item			26
Rentable Square Feet, Disposed | ft²			1,260,398
Net Sales Proceeds	[6]		$ 73,393
Net Carrying Value			56,186
Realized Gain (loss)/Unrealized Loss, net			17,207
Net sales proceeds held by qualified intermediary			15,300
Disposal Group, Not Discontinued Operations [Member] | 1 Enterprise Boulevard [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net Sales Proceeds			3,230
Net Carrying Value			1,380
Realized Gain (loss)/Unrealized Loss, net			$ 1,850
Disposal Group, Not Discontinued Operations [Member] | 61 South Paramus Road [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item			1
Rentable Square Feet, Disposed | ft²			269,191
Net Sales Proceeds			$ 23,255
Net Carrying Value			37,184
Realized Gain (loss)/Unrealized Loss, net			$ (13,929)
Disposal Group, Not Discontinued Operations [Member] | 300 Tice Boulevard [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item			1
Rentable Square Feet, Disposed | ft²			230,000
Net Sales Proceeds			$ 28,847
Net Carrying Value			25,705
Realized Gain (loss)/Unrealized Loss, net			$ 3,142
Disposal Group, Not Discontinued Operations [Member] | 2 Independence Way [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item	[7]			1
Net Sales Proceeds	[7]			$ 4,119
Net Carrying Value	[7]			4,283
Realized Gain (loss)/Unrealized Loss, net	[7]			$ (164)
Impairments					3,200
Disposal Group, Not Discontinued Operations [Member] | 1201 Connecticut Avenue, NW [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item				1
Net Sales Proceeds				$ 90,591
Net Carrying Value				31,827
Realized Gain (loss)/Unrealized Loss, net				$ 58,764
Disposal Group, Not Discontinued Operations [Member] | 125 Broad Street [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item	[8]			1
Net Sales Proceeds	[8]			$ 192,323
Net Carrying Value	[8]			200,183
Realized Gain (loss)/Unrealized Loss, net	[8]			$ (7,860)
Impairments					83,200
Disposal Group, Not Discontinued Operations [Member] | 9200 Edmonston Road [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item				1
Net Sales Proceeds	[9]			$ 4,083
Net Carrying Value				3,837
Realized Gain (loss)/Unrealized Loss, net				$ 246
Impairments						$ 3,000
Disposal Group, Not Discontinued Operations [Member] | 1400 L Street [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item				1
Net Sales Proceeds				$ 68,399
Net Carrying Value				30,053
Realized Gain (loss)/Unrealized Loss, net				$ 38,346
Disposal Group, Not Discontinued Operations [Member] | 600 Parsippany Road [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item				1
Net Sales Proceeds	[10]			$ 10,465
Net Carrying Value				5,875
Realized Gain (loss)/Unrealized Loss, net				$ 4,590
Net sales proceeds held by qualified intermediary		$ 10,500
Disposal Group, Not Discontinued Operations [Member] | 4, 5, 6 Century Drive [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item	[11]			3
Net Sales Proceeds	[11]			$ 14,533
Net Carrying Value	[11]			17,308
Realized Gain (loss)/Unrealized Loss, net	[11]			$ (2,775)
Impairments					9,800
Disposal Group, Not Discontinued Operations [Member] | Andover Place [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item				1
Net Sales Proceeds				$ 39,863
Net Carrying Value				37,150
Realized Gain (loss)/Unrealized Loss, net				$ 2,713
Disposal Group, Not Discontinued Operations [Member] | 222, 233 Mount Airy Road [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item	[12]			2
Net Sales Proceeds	[12]			$ 8,817
Net Carrying Value	[12]			9,039
Realized Gain (loss)/Unrealized Loss, net	[12]			$ (222)
Impairments					1,000
Disposal Group, Not Discontinued Operations [Member] | 10 Mountainview Road [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item				1
Net Sales Proceeds				$ 18,990
Net Carrying Value				19,571
Realized Gain (loss)/Unrealized Loss, net				$ (581)
Disposal Group, Not Discontinued Operations [Member] | 100 Willowbrook, 2, 3, 4 Paragon [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item	[13]			4
Net Sales Proceeds	[13]			$ 14,634
Net Carrying Value	[13]			19,377
Realized Gain (loss)/Unrealized Loss, net	[13]			$ (4,743)
Impairments					7,400
Disposal Group, Not Discontinued Operations [Member] | 4 Becker Farm Road [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item				1
Net Sales Proceeds	[14]			$ 41,400
Net Carrying Value				31,001
Realized Gain (loss)/Unrealized Loss, net				$ 10,399
Disposal Group, Not Discontinued Operations [Member] | 101, 103, 105 Eisenhower Parkway [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item				3
Net Sales Proceeds				$ 46,423
Net Carrying Value				45,999
Realized Gain (loss)/Unrealized Loss, net				$ 424
Disposal Group, Not Discontinued Operations [Member] | Capital Office Park, Ivy Lane [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item	[15]			6
Net Sales Proceeds	[15]			$ 46,570
Net Carrying Value	[15]			65,064
Realized Gain (loss)/Unrealized Loss, net	[15]			$ (18,494)
Impairments					66,500
Disposal Group, Not Discontinued Operations [Member] | 100 Walnut Avenue [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item				1
Net Sales Proceeds				$ 28,428
Net Carrying Value				7,529
Realized Gain (loss)/Unrealized Loss, net				$ 20,899
Disposal Group, Not Discontinued Operations [Member] | 20 Commerce Drive [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item				1
Net Sales Proceeds				$ 28,878
Net Carrying Value				13,071
Realized Gain (loss)/Unrealized Loss, net				$ 15,807
Disposal Group, Not Discontinued Operations [Member] | 4200 Parliament Place [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings, Disposed | item	[16]			1
Net Sales Proceeds	[16]			$ 5,965
Net Carrying Value	[16]			5,983
Realized Gain (loss)/Unrealized Loss, net	[16]			$ (18)
Impairments					$ 4,200
[1]	The Company recorded a valuation allowance of $7.7 million on this property during the year ended December 31, 2016.
[2]	At closing, the Company provided short term seller financing aggregating $65 million through mortgage notes receivable to the buyers. These notes were paid off in November and December 2017.
[3]	This disposition is of a ground leased land property.
[4]	The Company recorded an impairment charge of $7.0 million on this property during the year ended December 31, 2015.
[5]	The Company recorded an impairment charge of $4.2 million on this property during the year ended December 31, 2015. $5.9 million of the sales proceeds from this sale were held by a qualified intermediary, which is noncash and recorded in deferred charges, goodwill and other assets as of December 31, 2017. See Note 5: Deferred Charges, Goodwill and Other Assets, Net.
[6]	$15.3 million of the sales proceeds from this sale were held by a qualified intermediary, which is noncash and recorded in deferred charges, goodwill and other assets as of December 31, 2017. See Note 5: Deferred Charges, Goodwill and Other Assets, Net.
[7]	The Company recorded an impairment charge of $3.2 million on this property during the year ended December 31, 2015.
[8]	The Company recorded impairment charges of $83.2 million on this property during the year ended December 31, 2015.
[9]	The Company transferred the deed for this property to the lender in satisfaction of its obligations. The Company recorded an impairment charge of $3.0 million on this property during the year ended December 31, 2012.
[10]	$10.5 million of the net sales proceeds from this sale were held by a qualified intermediary. The Company received these proceeds on January 11, 2017.
[11]	The Company recorded impairment charges of $9.8 million on these properties during the year ended December 31, 2015.
[12]	The Company recorded impairment charges of $1.0 million on these properties during the year ended December 31, 2015.
[13]	The Company recorded impairment charges of $7.4 million on these properties during the year ended December 31, 2015.
[14]	The Company transferred the deed for this property to the lender in satisfaction of its obligations.
[15]	The Company recorded impairment charges of $66.5 million on these properties during the year ended December 31, 2015.
[16]	The Company recorded an impairment charge of $4.2 million on this property during the year ended December 31, 2015.

Recent Transactions (Summary Of

Recent Transactions (Summary Of Income From Property Held For Sale, Net) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Less - Accumulated depreciation	$ (1,087,083)	$ (1,332,073)
Rental property held for sale, net	171,578	39,743
Disposal Group, Held-for-sale, Not Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Land		10,934
Buildings and improvements		68,266
Less - Accumulated depreciation		(31,792)
Less: Unrealized losses on properties held for sale		(7,665)
Rental property held for sale, net		$ 39,743
Parsippany, Paramus, Rochelle Park, Hamilton And Wall, New Jersey And White Plains, New York [Member] | Disposal Group, Held-for-sale, Not Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Land	37,024
Buildings and improvements	273,388
Less - Accumulated depreciation	(126,503)
Less: Unrealized losses on properties held for sale	(12,331)
Rental property held for sale, net	$ 171,578

Investments In Unconsolidated60

Investments In Unconsolidated Joint Ventures (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)ft²propertyitem	Dec. 31, 2016USD ($)
Schedule of Equity Method Investments [Line Items]
Company's net investment in unconsolidated joint ventures	$ 252,626	$ 320,047
Amount outstanding	822,288	634,069
Management, leasing, development and other services fees	2,800	3,700
Accounts receivable due from unconsolidated joint ventures	800	$ 700
Maximum exposure to loss	165,500
Estimated future funding commitments	36,000
Property Debt, Balance	$ 45,734
Unconsolidated Joint Venture Office Buildings [Member]
Schedule of Equity Method Investments [Line Items]
Number of properties | property	4
Area of property (in square feet) | ft²	500,000
Unconsolidated Joint Venture Retail Buildings [Member]
Schedule of Equity Method Investments [Line Items]
Number of properties | property	2
Area of mixed use project (in square feet) | ft²	81,700
Unconsolidated Joint Venture Multi-Family Properties [Member]
Schedule of Equity Method Investments [Line Items]
Number of properties | property	8
Number of units | item	3,275
Unconsolidated Joint Venture Hotel [Member]
Schedule of Equity Method Investments [Line Items]
Number of units | item	350
Unconsolidated Joint Venture Development Projects [Member]
Schedule of Equity Method Investments [Line Items]
Number of units | item	419
Unconsolidated Joint Venture Land Parcels [Member]
Schedule of Equity Method Investments [Line Items]
Number of units | item	3,738
Unconsolidated Joint Ventures [Member] | Guarantee of Indebtedness of Others [Member]
Schedule of Equity Method Investments [Line Items]
Maximum borrowing capacity	$ 318,000
Amount outstanding	200,100
Unconsolidated Joint Ventures [Member] | Parent Company [Member] | Guarantee of Indebtedness of Others [Member]
Schedule of Equity Method Investments [Line Items]
Maximum borrowing capacity	36,000
Amount outstanding	$ 24,000
Minimum [Member]
Schedule of Equity Method Investments [Line Items]
Percentage of interest in venture	12.50%
Maximum [Member]
Schedule of Equity Method Investments [Line Items]
Percentage of interest in venture	85.00%
Variable Interest Entity [Member]
Schedule of Equity Method Investments [Line Items]
Company's net investment in unconsolidated joint ventures	$ 129,500
Number of VIEs | property	4

Investments In Unconsolidated61

Investments In Unconsolidated Joint Ventures (Summary Of Unconsolidated Joint Ventures) (Details) $ in Thousands

Dec. 07, 2017

Sep. 29, 2017USD ($)

Sep. 21, 2017USD ($)

Mar. 31, 2017USD ($)

Feb. 15, 2017USD ($)

Feb. 03, 2017USD ($)item

Apr. 01, 2016USD ($)

Feb. 03, 2007

Oct. 31, 2016

Jun. 30, 2017USD ($)

Dec. 31, 2017USD ($)ft²item

Dec. 31, 2016USD ($)

Dec. 31, 2015USD ($)

Feb. 28, 2017shares

Feb. 02, 2017

May 26, 2016item

Schedule of Equity Method Investments [Line Items]

Carrying Amount

$ 252,626

$ 320,047

Property Debt, Balance

45,734

Cash consideration

$ 2,000

Accounts payable, accrued expenses and other liabilities

192,716

159,874

Mortgage loan face amount

44,695

Purchase price of property

90,068

121,582

$ 94,073

Proceeds from the sale of investments in unconsolidated joint ventures

110,269

6,420

6,448

Debt

2,809,568

Gain (loss) on sale of investment in unconsolidated joint venture

$ 23,131

5,670

$ 6,448

Minimum [Member]

Schedule of Equity Method Investments [Line Items]

Company's Effective Ownership %

12.50%

Maximum [Member]

Schedule of Equity Method Investments [Line Items]

Company's Effective Ownership %

85.00%

RoseGarden Monaco Holdings, L.L.C. [Member]

Schedule of Equity Method Investments [Line Items]

Company's Effective Ownership %

13.80%

Gain (loss) on sale of investment in unconsolidated joint venture

$ (1,400)

PruRose Riverwalk G, L.L.C. [Member]

Schedule of Equity Method Investments [Line Items]

Number of units | item

316

Purchase price of property

$ 11,300

Percent of pari passu interest

22.50%

Crystal House Apartments Investors LLC [Member]

Schedule of Equity Method Investments [Line Items]

Percentage of interest in developable land

50.00%

Number of units available for development | item

295

Number of approved units available for development | item

252

Riverwalk C Urban Renewal, L.L.C. [Member]

Schedule of Equity Method Investments [Line Items]

Subordinate interest

20.00%

Percent of pari passu interest

40.00%

RoseGarden Marbella South, L.L.C. [Member] | Construction Loan [Member]

Schedule of Equity Method Investments [Line Items]

Number of extension options | item

2

Loan extension period

1 year

1 year

Extension fee

0.25%

Maximum borrowing capacity

$ 75,000

$ 77,400

Harborside Unit A Urban Renewal, LLC [Member]

Schedule of Equity Method Investments [Line Items]

Company's Effective Ownership %

85.00%

Harborside Unit A Urban Renewal, LLC [Member] | Construction/Permanent Loan [Member]

Schedule of Equity Method Investments [Line Items]

Maximum borrowing capacity

$ 192,000

RoseGarden Monaco, L.L.C. [Member]

Schedule of Equity Method Investments [Line Items]

Gain (loss) on sale of investment in unconsolidated joint venture

$ (1,400)

Plaza VIII & IX Associates, L.L.C. [Member]

Schedule of Equity Method Investments [Line Items]

Company's Effective Ownership %

50.00%

PruRose Port Imperial South 15, L.L.C. [Member]

Schedule of Equity Method Investments [Line Items]

Number of units | item

236

Percentage of interest in venture

50.00%

PruRose Port Imperial South 13, L.L.C. [Member]

Schedule of Equity Method Investments [Line Items]

Percentage of interest in venture

20.00%

KPG-MCG Curtis JV, LLC [Member]

Schedule of Equity Method Investments [Line Items]

Proceeds from the sale of investments in unconsolidated joint ventures

$ 102,500

Debt

75,000

Gain (loss) on sale of investment in unconsolidated joint venture

$ 12,000

The Shops At 40 Park Property [Member] | Rosewood Morristown, L.L.C. [Member]

Schedule of Equity Method Investments [Line Items]

Rentable Square Feet (sf) | ft²

50,973

Property Debt, Balance

$ 6,200

Property Debt, Maturity Date

Aug. 1, 2018

Property Debt, Interest Rate

3.63%

Residual ownership interest

12.50%

Lofts At 40 Park Property [Member] | Rosewood Morristown, L.L.C. [Member]

Schedule of Equity Method Investments [Line Items]

Number of units | item

59

Property Debt, Balance

$ 10,200

Indirect ownership interest

25.00%

Number of stories | item

5

Lofts At 40 Park Property [Member] | Rosewood Morristown, L.L.C. [Member] | Construction Loan [Member]

Schedule of Equity Method Investments [Line Items]

Property Debt, Maturity Date

Feb. 1, 2020

Property Debt, Interest Rate, Spread Over LIBOR

2.50%

Number of extension options | item

2

Loan extension period

1 year

Extension fee

0.15%

Metropolitan Property [Member] | RoseGarden Monaco Holdings, L.L.C. [Member]

Schedule of Equity Method Investments [Line Items]

Preferred units shares issued | shares

9,122

Metropolitan Property [Member] | Rosewood Morristown, L.L.C. [Member]

Schedule of Equity Method Investments [Line Items]

Property Debt, Balance

$ 36,800

Property Debt, Maturity Date

Sep. 1, 2020

Property Debt, Interest Rate

3.25%

Port Imperial North Land [Member] | Roseland/Port Imperial Partners, L.P. [Member]

Schedule of Equity Method Investments [Line Items]

Number of units | item

836

Residual ownership interest

20.00%

Unconsolidated Joint Venture Multi-Family Properties [Member]

Schedule of Equity Method Investments [Line Items]

Number of units | item

3,275

Unconsolidated Joint Venture Multi-Family Properties [Member] | Marbella RoseGarden, L.L.C. [Member]

Schedule of Equity Method Investments [Line Items]

Number of units | item

412

Company's Effective Ownership %

[1]

24.27%

Carrying Amount

$ 14,544

15,150

Property Debt, Balance

$ 95,000

Property Debt, Maturity Date

May 1, 2018

Property Debt, Interest Rate

4.99%

Unconsolidated Joint Venture Multi-Family Properties [Member] | RoseGarden Monaco Holdings, L.L.C. [Member]

Schedule of Equity Method Investments [Line Items]

Number of units | item

[2]

523

Unconsolidated Joint Venture Multi-Family Properties [Member] | Rosewood Morristown, L.L.C. [Member]

Schedule of Equity Method Investments [Line Items]

Number of units | item

[3],[4]

130

Company's Effective Ownership %

[1],[3],[4]

12.50%

Carrying Amount

[3],[4]

$ 6,834

7,145

Property Debt, Balance

[3],[4],[5]

$ 53,224

Unconsolidated Joint Venture Multi-Family Properties [Member] | Riverwalk G Urban Renewal, L.L.C. [Member]

Schedule of Equity Method Investments [Line Items]

Number of units | item

316

Company's Effective Ownership %

[1]

22.50%

Carrying Amount

$ 8,864

9,707

Property Debt, Balance

$ 82,000

Property Debt, Maturity Date

Nov. 10, 2026

Property Debt, Interest Rate

3.21%

Unconsolidated Joint Venture Multi-Family Properties [Member] | Elmajo Urban Renewal Associates, L.L.C. [Member]

Schedule of Equity Method Investments [Line Items]

Number of units | item

[6]

355

Company's Effective Ownership %

[1],[6]

7.50%

Gain (loss) on sale of investment in unconsolidated joint venture

$ 5,100

Unconsolidated Joint Venture Multi-Family Properties [Member] | Crystal House Apartments Investors LLC [Member]

Schedule of Equity Method Investments [Line Items]

Number of units | item

[7]

825

Company's Effective Ownership %

[1],[7]

25.00%

Carrying Amount

[7]

$ 30,570

30,565

Property Debt, Balance

[7]

$ 165,000

Property Debt, Maturity Date

[7]

Apr. 1, 2020

Property Debt, Interest Rate

[7]

3.17%

Unconsolidated Joint Venture Multi-Family Properties [Member] | Riverwalk C Urban Renewal, L.L.C. [Member]

Schedule of Equity Method Investments [Line Items]

Number of units | item

[8]

360

Company's Effective Ownership %

[1],[8]

40.00%

Carrying Amount

[8]

$ 16,844

Property Debt, Maturity Date

[8]

Dec. 6, 2021

Property Debt, Interest Rate, LIBOR

[8]

L+2.75

Property Debt, Interest Rate, Spread Over LIBOR

2.75%

Unconsolidated Joint Venture Multi-Family Properties [Member] | RoseGarden Marbella South, L.L.C. [Member]

Schedule of Equity Method Investments [Line Items]

Number of units | item

311

Company's Effective Ownership %

[1]

24.27%

Carrying Amount

$ 16,471

18,050

Property Debt, Balance

$ 74,690

Property Debt, Maturity Date

Mar. 30, 2018

Property Debt, Interest Rate, LIBOR

[9]

L+2.25

Property Debt, Interest Rate, Spread Over LIBOR

[9]

2.25%

Unconsolidated Joint Venture Multi-Family Properties [Member] | Estuary Urban Renewal Unit B, LLC [Member]

Schedule of Equity Method Investments [Line Items]

Number of units | item

227

Company's Effective Ownership %

[1]

7.50%

Unconsolidated Joint Venture Multi-Family Properties [Member] | Riverpark At Harrison I, L.L.C. [Member]

Schedule of Equity Method Investments [Line Items]

Number of units | item

141

Company's Effective Ownership %

[1]

45.00%

Carrying Amount

$ 1,604

2,085

Property Debt, Balance

$ 30,000

Property Debt, Maturity Date

Aug. 1, 2025

Property Debt, Interest Rate

3.70%

Unconsolidated Joint Venture Multi-Family Properties [Member] | Capitol Place Mezz LLC [Member]

Schedule of Equity Method Investments [Line Items]

Number of units | item

378

Company's Effective Ownership %

[1]

50.00%

Carrying Amount

$ 40,124

43,073

Property Debt, Balance

$ 100,070

Property Debt, Maturity Date

Jul. 1, 2033

Property Debt, Interest Rate

4.82%

Unconsolidated Joint Venture Multi-Family Properties [Member] | Harborside Unit A Urban Renewal, LLC [Member]

Schedule of Equity Method Investments [Line Items]

Number of units | item

762

Company's Effective Ownership %

[1]

85.00%

Carrying Amount

$ 94,429

100,188

Property Debt, Balance

$ 189,853

Property Debt, Maturity Date

Aug. 1, 2029

Property Debt, Interest Rate

[10]

5.197%

Unconsolidated Joint Venture Multi-Family Properties [Member] | Roseland/Port Imperial Partners, L.P. [Member]

Schedule of Equity Method Investments [Line Items]

Number of units | item

[11]

836

Company's Effective Ownership %

[1],[11]

20.00%

Carrying Amount

[11]

$ 1,678

1,678

Unconsolidated Joint Venture Multi-Family Properties [Member] | RoseGarden Monaco, L.L.C. [Member]

Schedule of Equity Method Investments [Line Items]

Number of units | item

[12]

250

Company's Effective Ownership %

[1],[12]

41.67%

Carrying Amount

[12]

1,400

Unconsolidated Joint Venture Multi-Family Properties [Member] | Grand Jersey Waterfront URA, L.L.C. [Member]

Schedule of Equity Method Investments [Line Items]

Number of units | item

850

Company's Effective Ownership %

[1]

50.00%

Carrying Amount

$ 337

337

Unconsolidated Joint Venture Multi-Family Properties [Member] | Hillsborough 206 Holdings, L.L.C. [Member]

Schedule of Equity Method Investments [Line Items]

Rentable Square Feet (sf) | ft²

160,000

Company's Effective Ownership %

[1]

50.00%

Carrying Amount

$ 1,962

1,962

Unconsolidated Joint Venture Multi-Family Properties [Member] | Plaza VIII & IX Associates, L.L.C. [Member]

Schedule of Equity Method Investments [Line Items]

Rentable Square Feet (sf) | ft²

[13]

1,225,000

Company's Effective Ownership %

[1],[13]

50.00%

Carrying Amount

[13]

4,448

Unconsolidated Joint Venture Multi-Family Properties [Member] | Elmajo Urban Renewal Associates, LLC And Estuary Urban Renewal Associates, LLC [Member]

Schedule of Equity Method Investments [Line Items]

Company's Effective Ownership %

7.50%

Percentage of interest in venture

7.50%

Proceeds from the sale of investments in unconsolidated joint ventures

$ 5,100

Gain (loss) on sale of investment in unconsolidated joint venture

$ 5,100

Unconsolidated Joint Venture Office Buildings [Member]

Schedule of Equity Method Investments [Line Items]

Rentable Square Feet (sf) | ft²

500,000

Unconsolidated Joint Venture Office Buildings [Member] | Red Bank Corporate Plaza, L.L.C. [Member]

Schedule of Equity Method Investments [Line Items]

Rentable Square Feet (sf) | ft²

92,878

Company's Effective Ownership %

[1]

50.00%

Carrying Amount

$ 4,602

4,339

Property Debt, Balance

$ 13,876

Property Debt, Maturity Date

May 17, 2018

Property Debt, Interest Rate, LIBOR

L+3.00

Property Debt, Interest Rate, Spread Over LIBOR

3.00%

Unconsolidated Joint Venture Office Buildings [Member] | 12 Vreeland Associates, L.L.C. [Member]

Schedule of Equity Method Investments [Line Items]

Rentable Square Feet (sf) | ft²

139,750

Company's Effective Ownership %

[1]

50.00%

Carrying Amount

$ 6,734

6,237

Property Debt, Balance

$ 9,495

Property Debt, Maturity Date

Jul. 1, 2023

Property Debt, Interest Rate

2.87%

Unconsolidated Joint Venture Office Buildings [Member] | BNES Associates III [Member]

Schedule of Equity Method Investments [Line Items]

Rentable Square Feet (sf) | ft²

106,345

Company's Effective Ownership %

[1]

31.25%

Carrying Amount

$ 3,369

3,124

Property Debt, Balance

$ 4,794

Property Debt, Maturity Date

Nov. 1, 2023

Property Debt, Interest Rate

4.76%

Unconsolidated Joint Venture Office Buildings [Member] | KPG-P 100 IMW JV, LLC [Member]

Schedule of Equity Method Investments [Line Items]

Rentable Square Feet (sf) | ft²

[14]

339,615

Property Debt, Interest Rate, LIBOR

-

Unconsolidated Joint Venture Office Buildings [Member] | Keystone-Penn [Member]

Schedule of Equity Method Investments [Line Items]

Rentable Square Feet (sf) | ft²

[14]

1,842,820

Company's Effective Ownership %

[1]

Unconsolidated Joint Venture Office Buildings [Member] | Keystone-TriState [Member]

Schedule of Equity Method Investments [Line Items]

Rentable Square Feet (sf) | ft²

[14]

1,266,384

Company's Effective Ownership %

[1]

Carrying Amount

2,285

Unconsolidated Joint Venture Office Buildings [Member] | KPG-MCG Curtis JV, LLC [Member]

Schedule of Equity Method Investments [Line Items]

Rentable Square Feet (sf) | ft²

[15]

885,000

Carrying Amount

65,400

Unconsolidated Joint Venture Other Property [Member]

Schedule of Equity Method Investments [Line Items]

Carrying Amount

$ 252,626

320,047

Property Debt, Balance

$ 917,137

Unconsolidated Joint Venture Other Property [Member] | Roseland/North Retail, L.L.C. [Member]

Schedule of Equity Method Investments [Line Items]

Rentable Square Feet (sf) | ft²

30,745

Company's Effective Ownership %

[1]

20.00%

Carrying Amount

$ 1,625

1,706

Unconsolidated Joint Venture Other Property [Member] | South Pier At Harborside [Member]

Schedule of Equity Method Investments [Line Items]

Number of units | item

350

Company's Effective Ownership %

[1]

50.00%

Carrying Amount

$ 440

163

Property Debt, Balance

$ 99,135

Property Debt, Maturity Date

Oct. 1, 2026

Property Debt, Interest Rate

3.668%

Unconsolidated Joint Venture Other Property [Member] | Other [Member]

Schedule of Equity Method Investments [Line Items]

Carrying Amount

[16]

$ 1,595

$ 1,005

[1]

Company's effective ownership % represents the Company's entitlement to residual distributions after payments of priority returns, where applicable.

[2]

On February 28, 2017, 9,122 Series A-1 Units were issued to the joint venture partner as noncash consideration for the partner's approximate 13.8 percent ownership interest in the joint venture. In April 2017, the Company acquired the remaining joint venture interests and increased its ownership interest to 100 percent. See Note 3: Recent Transactions - Consolidation.

[3]

The Company's ownership interests in this venture are subordinate to its partner's preferred capital balance and the Company is not expected to meaningfully participate in the venture's cash flows in the near term.

[4]

Through the joint venture, the Company also owns a 12.5 percent interest in a 50,973 square feet retail building ("Shops at 40 Park") and a 25 percent interest in a to-be-built 59-unit, five story multi-family rental development property ("Lofts at 40 Park").

[5]

Property debt balance consists of: (i) an amortizable loan, collateralized by the Metropolitan at 40 Park, with a balance of $36.8 million bears interest at 3.25 percent, matures in September 2020; (ii) an amortizable loan, collateralized by the Shops at 40 Park, with a balance of $6.2 million, bears interest at 3.63 percent, matures in August 2018. On February 3, 2017, the venture obtained a construction loan for the Lofts at 40 Park with a balance of $10. 2 million, which bears interest at LIBOR plus 250 basis points and matures in February 2020 and provides, subject to certain conditions, two one-year extension options with a fee of 15 basis points for each year.

[6]

On February 15, 2017, the Company sold its 7.5 percent interest in Elmajo Urban Renewal Associates, LLC and Estuary Urban Renewal Unit B, LLC joint ventures that own operating multi-family properties, located in Weehawken, New Jersey for a combined sales price of $5.1 million.

[7]

The Company also owns a 50 percent interest in a vacant land to accommodate the development of approximately 295 additional units of which 252 are currently approved.

[8]

On December 7, 2017, simultaneous with the financing of the construction loan, the Company converted its 20 percent subordinate interest to 40 percent pari-passu interest.

[9]

The construction loan had a maximum borrowing amount of $77.4 million and provided, subject to certain conditions, two one-year extension options with a fee of 25 basis points for each year. On March 31, 2017, the Company exercised its first one-year extension option and concurrently the maximum borrowing amount was reduced to $75 million.

[10]

The construction/permanent loan has a maximum borrowing amount of $192 million. The Company owns an 85 percent interest with shared control over major decisions such as, approval of budgets, property financings and leasing guidelines. The development project was placed in service in second quarter 2017.

[11]

The Company also owns a 20 percent residual interest in undeveloped land parcels: parcels 6, I, and J that can accommodate the development of 836 apartment units.

[12]

On September 21, 2017, the joint venture agreement was terminated. Accordingly, the Company wrote off the carrying value of its investment in the joint venture and recorded a loss of $1.4 million on the disposition of its joint venture interest.

[13]

On February 3, 2017, the Company acquired the equity interest of its partner. See Note 3: Recent Transactions - Consolidation.

[14]

On January 31, 2017, the Company sold its equity interest in the joint venture. See Note 3: Recent Transactions - Unconsolidated Joint Venture Activity.

[15]

Includes undivided interests in the same manner as investments in noncontrolling partnership, pursuant to ASC 970-323-25-12. On September 29, 2017, the Company sold its equity interest to its joint venture partner, which included the retirement of the Company's share in the debt of $75 million. See Note 3: Recent Transactions - Unconsolidated Joint Venture Activity.

[16]

The Company owns other interests in various unconsolidated joint ventures, including interests in assets previously owned and interest in ventures whose businesses are related to its core operations. These ventures are not expected to significantly impact the Company's operations in the near term.

Investments In Unconsolidated62

Investments In Unconsolidated Joint Ventures (Summary Of Company's Equity In Earnings (Loss) Of Unconsolidated Joint Ventures) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	[1]	$ (6,081)	$ 18,788	$ (3,172)
Amortization of basis difference		792	436	336
Unconsolidated Joint Venture Multi-Family Properties [Member] | Marbella RoseGarden, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures		334	231	231
Unconsolidated Joint Venture Multi-Family Properties [Member] | RoseGarden Monaco Holdings, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures		(265)	(937)	(1,224)
Unconsolidated Joint Venture Multi-Family Properties [Member] | Rosewood Morristown, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures		(311)	(317)	(364)
Unconsolidated Joint Venture Multi-Family Properties [Member] | Riverwalk G Urban Renewal, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures		196	(1,146)	(955)
Unconsolidated Joint Venture Multi-Family Properties [Member] | Crystal House Apartments Investors LLC [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures		(923)	(870)	(123)
Unconsolidated Joint Venture Multi-Family Properties [Member] | Riverpark At Harrison I, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures		(252)	(190)	(363)
Unconsolidated Joint Venture Multi-Family Properties [Member] | Riverwalk C Urban Renewal, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures		(653)	(58)	(306)
Unconsolidated Joint Venture Multi-Family Properties [Member] | RoseGarden Marbella South, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures		93	(202)
Unconsolidated Joint Venture Multi-Family Properties [Member] | Estuary Urban Renewal Unit B, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures				1
Unconsolidated Joint Venture Multi-Family Properties [Member] | Capitol Place Mezz LLC [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures		(1,793)	(2,440)	(3,687)
Unconsolidated Joint Venture Multi-Family Properties [Member] | Harborside Unit A Urban Renewal, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures		(6,356)	(219)
Unconsolidated Joint Venture Multi-Family Properties [Member] | Roseland/Port Imperial Partners, L.P. [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures		(219)	(62)	(168)
Unconsolidated Joint Venture Multi-Family Properties [Member] | Grand Jersey Waterfront URA, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures		(15)	(80)	(32)
Unconsolidated Joint Venture Multi-Family Properties [Member] | Hillsborough 206 Holdings, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures		(25)	(53)	(5)
Unconsolidated Joint Venture Multi-Family Properties [Member] | Plaza VIII & IX Associates, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures		386	393	344
Unconsolidated Joint Venture Office Buildings [Member] | Red Bank Corporate Plaza, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures		238	448	392
Unconsolidated Joint Venture Office Buildings [Member] | 12 Vreeland Associates, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures		496	347	270
Unconsolidated Joint Venture Office Buildings [Member] | BNES Associates III [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures		89	(15)	115
Unconsolidated Joint Venture Office Buildings [Member] | KPG-P 100 IMW JV, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures				(800)
Unconsolidated Joint Venture Office Buildings [Member] | Keystone-Penn [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures			600	3,812
Unconsolidated Joint Venture Office Buildings [Member] | Keystone-TriState [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures			(1,672)	(2,182)
Unconsolidated Joint Venture Office Buildings [Member] | KPG-MCG Curtis JV, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures		(436)	(92)	475
Unconsolidated Joint Venture Other Property [Member] | Roseland/North Retail, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures		(81)	(52)	(70)
Unconsolidated Joint Venture Other Property [Member] | South Pier At Harborside [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	[2]	3,277	24,180	3,036
Unconsolidated Joint Venture Other Property [Member] | Other [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures		$ 139	$ 994	$ (1,569)
[1]	Amounts are net of amortization of basis differences of $792, $436 and $336 for the years ended December 31, 2017, 2016 and 2015, respectively.
[2]	Equity in earnings in 2016 includes the effect of distributions received from the joint venture's refinancing. See Recent Joint Venture Transactions following in this footnote.

Investments In Unconsolidated63

Investments In Unconsolidated Joint Ventures (Summary Of Financial Position Of Unconsolidated Joint Ventures) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Investments In Unconsolidated Joint Ventures [Abstract]
Rental property, net	$ 931,419	$ 1,746,233
Other assets	207,903	278,289
Total assets	1,139,322	2,024,522
Mortgages and loans payable	689,412	1,350,973
Other liabilities	80,746	247,212
Partners'/members' capital	369,164	426,337
Total liabilities and partners'/members' capital	$ 1,139,322	$ 2,024,522

Investments In Unconsolidated64

Investments In Unconsolidated Joint Ventures (Summary Of Results Of Operations Of Unconsolidated Joint Ventures) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Investments In Unconsolidated Joint Ventures [Abstract]
Total revenues	$ 358,751	$ 377,711	$ 318,980
Operating and other expenses	(297,492)	(262,703)	(220,982)
Depreciation and amortization	(31,020)	(75,512)	(71,711)
Interest expense	(25,822)	(58,390)	(52,972)
Net income (loss)	$ 4,417	$ (18,894)	$ (26,685)

Deferred Charges, Goodwill An65

Deferred Charges, Goodwill And Other Assets, Net (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Credit Risk Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net liability	$ 0
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative notional amount	675,000,000
Ineffective gain (loss) in interest expense	(37,000)	$ 600,000	$ 0
Estimated additional amount to be reclassified to interest expense	1,500,000
Not Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of increase in the fair value of derivatives	$ 0	$ 2,000	$ 93,000

Deferred Charges, Goodwill An66

Deferred Charges, Goodwill And Other Assets, Net (Schedule Of Deferred Charges, Goodwill And Other Assets) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Aug. 31, 2017
Deferred Charges, Goodwill And Other Assets [Line Items]
Deferred leasing costs		$ 199,515	$ 220,947
Deferred financing costs - unsecured revolving credit facility	[1]	4,945	5,400
Deferred charges, gross		204,460	226,347
Accumulated amortization		(98,956)	(107,359)
Deferred charges, net		105,504	118,988
Notes receivable	[2]	50,167	13,251
In-place lease values, related intangibles and other assets, net	[3],[4]	102,757	72,046
Goodwill	[5]	2,945	2,945
Prepaid expenses and other assets, net	[6]	80,947	60,720
Total deferred charges, goodwill and other assets, net		342,320	267,950
Lease revenue		501,334	506,877	$ 487,041
Acquired Above And Below Market Lease Intangibles [Member]
Deferred Charges, Goodwill And Other Assets [Line Items]
Lease revenue		7,900	$ 1,900	$ 200
Acquisition-related Costs [Member]
Deferred Charges, Goodwill And Other Assets [Line Items]
Net sales proceeds held by qualified intermediary		$ 26,900
Notes Receivable 5.85 Interest Rate [Member]
Deferred Charges, Goodwill And Other Assets [Line Items]
Mortgage loan, maturity date		Jul. 1, 2019
Interest rate		5.85%
Notes receivable		$ 45,700			$ 44,700
Loan extension period		3 months
Interest-Free Notes Receivable [Member]
Deferred Charges, Goodwill And Other Assets [Line Items]
Mortgage loan, maturity date		Apr. 1, 2023
Notes receivable		$ 2,500
Disposal Group, Not Discontinued Operations [Member] | Buyer [Member] | Bergen Portfolio [Member]
Deferred Charges, Goodwill And Other Assets [Line Items]
Notes receivable		$ 65,000
[1]	Deferred financing costs related to all other debt liabilities (other than for the unsecured revolving credit facility) are netted against those debt liabilities for all periods presented. See Note 2: Significant Accounting Policies - Deferred Financing Costs.
[2]	Includes as of December 31, 2017: a mortgage receivable with a balance of $45.7 million (acquired in August 2017) which bears interest at 5.85 percent and matures in July 2019, with a three-month extension option and an interest-free note receivable with a net present value of $2.5 million which matures in April 2023. The Company believes these balances are fully collectible.
[3]	In accordance with ASC 805, Business Combinations, the Company recognizes rental revenue of acquired above and below market lease intangibles over the terms of the respective leases. The impact of amortizing the acquired above and below-market lease intangibles increased revenue by approximately $7.9 million, $1.9 million and $0.2 million for the years ended December 31, 2017, 2016 and 2015, respectively. The following table summarizes, as of December 31, 2017, the scheduled amortization of the Company's acquired above and below-market lease intangibles for each of the five succeeding years (dollars in thousands).
[4]	The value of acquired in-place lease intangibles are amortized to expense over the remaining initial terms of the respective leases. The impact of the amortization of acquired in-place lease values is included in depreciation and amortization expense and amounted to approximately $32.2 million, $14.3 million and $1.4 million for the years ended December 31, 2017, 2016 and 2015, respectively. The following table summarizes, as of December 31, 2017, the scheduled amortization of the Company's acquired in-place lease values for each of the five succeeding years (dollars in thousands).
[5]	All goodwill is attributable to the Company's Multi-family Services segment.
[6]	Includes as of December 31, 2017, $26.9 million of proceeds from property sales held by a qualified intermediary.

Deferred Charges, Goodwill An67

Deferred Charges, Goodwill And Other Assets (Summary Of Scheduled Amortization) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
2,018	$ 1,804
2,019	467
2,020	906
2,021	1,407
2,022	1,398
Above Market Leases [Member]
Finite-Lived Intangible Assets [Line Items]
2,018	(5,084)
2,019	(4,716)
2,020	(3,398)
2,021	(2,779)
2,022	(2,665)
Acquired Below-Market Lease Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
2,018	6,888
2,019	5,183
2,020	4,304
2,021	4,186
2,022	4,063
In-Place Leases [Member]
Finite-Lived Intangible Assets [Line Items]
2,018	10,657
2,019	8,406
2,020	7,078
2,021	6,347
2,022	5,526
Amortization expense	$ 32,200	$ 14,300	$ 1,400

Deferred Charges, Goodwill An68

Deferred Charges, Goodwill And Other Assets, Net (Schedule Of Fair Value Of The Derivative Financial Instruments) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Designated as Hedging Instrument [Member] | Interest Rate Swaps [Member] | Deferred Charges, Goodwill And Other Assets [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Asset Derivatives	$ 8,060	$ 2,847

Deferred Charges, Goodwill An69

Deferred Charges, Goodwill And Other Assets, Net (Schedule Of Cash Flow Hedging, Derivative Financial Instruments On The Income Statement) (Details) - Not Designated as Hedging Instrument [Member] - Cash Flow Hedging [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	$ (2,381)	$ (3,398)
Interest And Other Investment Income (Loss) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion, Reclassification for Forecasted Transactions No Longer Probable of Occurring and Amount Excluded from Effectiveness Testing)	(37)	631
Interest Rate Swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in OCI on Derivative (Effective Portion)	$ 2,869	$ (1,183)

Restricted Cash (Schedule Of Re

Restricted Cash (Schedule Of Restricted Cash) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Restricted Cash [Abstract]
Security deposits	$ 9,446	$ 8,778
Escrow and other reserve funds	30,346	45,174
Total restricted cash	$ 39,792	$ 53,952

Senior Unsecured Notes (Summary

Senior Unsecured Notes (Summary Of Senior Unsecured Notes) (Details) - USD ($)		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Principal balance outstanding		$ 2,809,568,000	$ 2,340,009,000
Adjustment for unamortized debt discount		(3,505,000)
Total senior unsecured notes, net		$ 2,809,568,000
2.500% Senior Unsecured Notes Due December 15, 2017 [Member]
Debt Instrument [Line Items]
Interest rate of senior unsecured notes		2.50%
Maturity date of the senior unsecured notes		Dec. 15, 2017
4.500% Senior Unsecured Notes Due April 18, 2022 [Member]
Debt Instrument [Line Items]
Interest rate of senior unsecured notes		4.50%
Maturity date of the senior unsecured notes		Apr. 18, 2022
3.150% Senior Unsecured Notes, Due May 15, 2023 [Member]
Debt Instrument [Line Items]
Interest rate of senior unsecured notes		3.15%
Maturity date of the senior unsecured notes		May 15, 2023
Unsecured Note [Member]
Debt Instrument [Line Items]
Principal balance outstanding		$ 575,000,000	825,000,000
Adjustment for unamortized debt discount		(3,505,000)	(4,430,000)
Unamortized deferred financing costs		(2,350,000)	(3,215,000)
Total senior unsecured notes, net		$ 569,145,000	817,355,000
Unsecured Note [Member] | 2.500% Senior Unsecured Notes Due December 15, 2017 [Member]
Debt Instrument [Line Items]
Principal balance outstanding	[1]		250,000,000
Effective rate	[1],[2]	2.803%
Unsecured Note [Member] | 4.500% Senior Unsecured Notes Due April 18, 2022 [Member]
Debt Instrument [Line Items]
Principal balance outstanding		$ 300,000,000	300,000,000
Effective rate	[2]	4.612%
Unsecured Note [Member] | 3.150% Senior Unsecured Notes, Due May 15, 2023 [Member]
Debt Instrument [Line Items]
Principal balance outstanding		$ 275,000,000	$ 275,000,000
Effective rate	[2]	3.517%
[1]	The Company repaid these notes at maturity using available cash and borrowings under the Company's unsecured revolving credit facility.
[2]	Includes the cost of terminated treasury lock agreements (if any), offering and other transaction costs and the discount/premium on the notes, as applicable.

Unsecured Revolving Credit Fa72

Unsecured Revolving Credit Facility And Term Loans (Narrative) (Details)	Jan. 25, 2017USD ($)entity	Dec. 31, 2017USD ($)item	Dec. 31, 2016USD ($)item	Mar. 29, 2017	Mar. 22, 2017USD ($)	Jan. 26, 2017USD ($)	Jan. 31, 2016USD ($)
Line of Credit Facility [Line Items]
Loan balance		$ 2,809,568,000	$ 2,340,009,000
Outstanding borrowings under the facility		822,288,000	$ 634,069,000
Unsecured Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Number of lending institutions | item			17
Borrowing capacity under the credit facility			$ 600,000,000
Outstanding borrowings under the facility		$ 150,000,000	286,000,000
2017 Credit Agreement [Member]
Line of Credit Facility [Line Items]
Number of lending institutions | entity	13
Borrowing capacity under the credit facility	$ 60,000,000
Terms of the unsecured facility		The 2017 Credit Agreement, which applies to both the 2017 Credit Facility and 2017 Term Loan, includes certain restrictions and covenants which limit, among other things the incurrence of additional indebtedness, the incurrence of liens and the disposition of real estate properties (to the extent that: (i) such property dispositions cause the Company to default on any of the financial ratios of the 2017 Credit Agreement (described below), or (ii) the property dispositions are completed while the Company is under an event of default under the 2017 Credit Agreement, unless, under certain circumstances, such disposition is being carried out to cure such default), and which require compliance with financial ratios relating to the maximum leverage ratio (60 percent), the maximum amount of secured indebtedness (40 percent), the minimum amount of fixed charge coverage (1.5 times), the maximum amount of unsecured indebtedness (60 percent), the minimum amount of unencumbered property interest coverage (2.0 times) and certain investment limitations (generally 15 percent of total capitalization).
Terms of dividend restriction		If an event of default has occurred and is continuing, the entire outstanding balance under the 2017 Credit Agreement may (or, in the case of any bankruptcy event of default, shall) become immediately due and payable, and the Company will not make any excess distributions except to enable the General Partner to continue to qualify as a REIT under the IRS Code.
2017 Credit Facility [Member]
Line of Credit Facility [Line Items]
Loan maturity date		Jan. 1, 2021
Borrowing capacity under the credit facility	600,000,000
Number of extension options | item		2
Credit facility, extension period		6 months
Terms of the unsecured facility		The terms of the 2017 Credit Facility include: (1) a four-year term ending in January 2021, with two six-month extension options; (2) revolving credit loans may be made to the Company in an aggregate principal amount of up to $600 million (subject to increase as discussed below), with a sublimit under the 2017 Credit Facility for the issuance of letters of credit in an amount not to exceed $60 million (subject to increase as discussed below); (3) an interest rate based on the Operating Partnership's unsecured debt ratings from Moody's or S&P, currently the London Inter-Bank Offered Rate ("LIBOR") plus 120 basis points, or, at the Operating Partnership's option, if it no longer maintains a debt rating from Moody's or S&P or such debt ratings fall below Baa3 and BBB-, based on a defined leverage ratio; and (4) a facility fee payable quarterly based on the Operating Partnership's unsecured debt ratings from Moody's or S&P, currently 25 basis points, or, at the Operating Partnership's option, if it no longer maintains a debt rating from Moody's or S&P or such debt ratings fall below Baa3 and BBB-, based on a defined leverage ratio.
Spread over LIBOR		1.20%
Loan period		4 years
Facility fee basis points		0.25%
2017 Credit Agreement, Letter Of Credit [Member]
Line of Credit Facility [Line Items]
Maximum loan increase that may be requested						$ 100,000,000
Unsecured Term Loan [Member] | Unsecured Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Outstanding borrowings under the facility		$ 822,300,000	634,100,000
5.800% Senior Unsecured Notes, Due January 15, 2016 [Member]
Line of Credit Facility [Line Items]
Loan balance							$ 200,000,000
Loan maturity date		Jan. 15, 2016
2017 Term Loan [Member]
Line of Credit Facility [Line Items]
Loan balance					$ 325,000,000
Loan maturity date		Jan. 1, 2020
Unamortized deferred financing costs		$ 1,700,000
Loan extension period		1 year
Interest rate swap				1.6473%
Interest rate				3.0473%
Borrowing capacity under the credit facility	$ 325,000,000
Number of extension options | item		2
Terms of the unsecured facility		The terms of the 2017 Term Loan include: (1) a three-year term ending in January 2020, with two one-year extension options; (2) multiple draws of the term loan commitments may be made within 12 months of the effective date of the 2017 Credit Agreement up to an aggregate principal amount of $325 million (subject to increase as discussed below), with no requirement to be drawn in full; provided, that, if the Company does not borrow at least 50 percent of the initial term commitment from the term lenders (i.e. 50 percent of $325 million) on or before July 25, 2017, the amount of unused term loan commitments shall be reduced on such date so that, after giving effect to such reduction, the amount of unused term loan commitments is not greater than the outstanding term loans on such date; (3) an interest rate based on the Operating Partnership's unsecured debt ratings from Moody's or S&P, currently the LIBOR plus 140 basis points, or, at the Operating Partnership's option if it no longer maintains a debt rating from Moody's or S&P or such debt ratings fall below Baa3 and BBB-, based on a defined leverage ratio; and (4) a term commitment fee on any unused term loan commitment during the first 12 months after the effective date of the 2017 Credit Agreement at a rate of 0.25 percent per annum on the sum of the average daily unused portion of the aggregate term loan commitments.
Outstanding borrowings under the facility		$ 323,300,000
Spread over LIBOR		1.40%
Loan period		3 years
Minimum percentage of initial borrowing		50.00%
Term commitment fee percent		0.25%
Incremental Commitments [Member]
Line of Credit Facility [Line Items]
Maximum loan increase that may be requested						$ 350,000,000
2016 Term Loan [Member]
Line of Credit Facility [Line Items]
Unsecured term loan, net							$ 350,000,000
Loan maturity date		Jan. 1, 2019
Unamortized deferred financing costs		$ 1,000,000	1,900,000
Interest rate		3.13%
Number of extension options | item		2
Credit facility, extension period		1 year
Terms of the unsecured facility		The terms of the 2016 Term Loan include certain restrictions and covenants which limit, among other things the incurrence of additional indebtedness, the incurrence of liens and the disposition of real estate properties (to the extent that: (i) such property dispositions cause the Company to default on any of the financial ratios of the term loan described below, or (ii) the property dispositions are completed while the Company is under an event of default under the term loan, unless, under certain circumstances, such disposition is being carried out to cure such default), and which require compliance with financial ratios relating to the maximum leverage ratio (60 percent), the maximum amount of secured indebtedness (40 percent), the minimum amount of fixed charge coverage (1.5 times), the maximum amount of unsecured indebtedness (60 percent), the minimum amount of unencumbered property interest coverage (2.0 times) and certain investment limitations (generally 15 percent of total capitalization).
Terms of dividend restriction		If an event of default has occurred and is continuing, the Company will not make any excess distributions except to enable the General Partner to continue to qualify as a REIT under the IRS Code. The Company was in compliance with its debt covenants under its unsecured revolving credit facility and term loans as of December 31, 2017.
Outstanding borrowings under the facility		$ 349,000,000	$ 348,100,000
Spread over LIBOR		1.40%

Unsecured Revolving Credit Fa73

Unsecured Revolving Credit Facility And Term Loans (Schedule Of Interest Rates On Outstanding Borrowings, Alternate Base Rate Loans, And Facility Fee) (Details) - 2017 Credit Facility [Member]	12 Months Ended
	Dec. 31, 2017
Line of Credit Facility [Line Items]
Interest Rate - Applicable Basis Points Above LIBOR	1.20%
Facility Fee Basis Points	0.25%
Mack-Cali Realty LP [Member] | No Ratings Or Less Than Baa3 [Member] | No Ratings Or Less Than BBB- [Member]
Line of Credit Facility [Line Items]
Unsecured Debt Ratings	No ratings or less than BBB-/Baa3
Interest Rate - Applicable Basis Points Above LIBOR	1.55%
Facility Fee Basis Points	0.30%
Mack-Cali Realty LP [Member] | Baa3 [Member] | BBB- [Member]
Line of Credit Facility [Line Items]
Unsecured Debt Ratings	BBB- or Baa3 (current interest rate based on Company's election)
Interest Rate - Applicable Basis Points Above LIBOR	1.20%
Facility Fee Basis Points	0.25%
Mack-Cali Realty LP [Member] | Baa2 [Member] | BBB [Member]
Line of Credit Facility [Line Items]
Unsecured Debt Ratings	BBB or Baa2
Interest Rate - Applicable Basis Points Above LIBOR	1.00%
Facility Fee Basis Points	0.20%
Mack-Cali Realty LP [Member] | Baa1 [Member] | BBB+ [Member]
Line of Credit Facility [Line Items]
Unsecured Debt Ratings	BBB+ or Baa1
Interest Rate - Applicable Basis Points Above LIBOR	0.90%
Facility Fee Basis Points	0.15%
Mack-Cali Realty LP [Member] | A3 Or Higher [Member] | A- Or Higher [Member]
Line of Credit Facility [Line Items]
Unsecured Debt Ratings	A- or A3 or higher
Interest Rate - Applicable Basis Points Above LIBOR	0.875%
Facility Fee Basis Points	0.125%
Mack-Cali Realty LP [Member] | Base Rate [Member] | No Ratings Or Less Than Baa3 [Member] | No Ratings Or Less Than BBB- [Member]
Line of Credit Facility [Line Items]
Interest Rate - Applicable Basis Points Above LIBOR	0.55%
Mack-Cali Realty LP [Member] | Base Rate [Member] | Baa3 [Member] | BBB- [Member]
Line of Credit Facility [Line Items]
Interest Rate - Applicable Basis Points Above LIBOR	0.20%
Mack-Cali Realty LP [Member] | Base Rate [Member] | Baa2 [Member] | BBB [Member]
Line of Credit Facility [Line Items]
Interest Rate - Applicable Basis Points Above LIBOR	0.00%
Mack-Cali Realty LP [Member] | Base Rate [Member] | Baa1 [Member] | BBB+ [Member]
Line of Credit Facility [Line Items]
Interest Rate - Applicable Basis Points Above LIBOR	0.00%
Mack-Cali Realty LP [Member] | Base Rate [Member] | A3 Or Higher [Member] | A- Or Higher [Member]
Line of Credit Facility [Line Items]
Interest Rate - Applicable Basis Points Above LIBOR	0.00%

Unsecured Revolving Credit Fa74

Unsecured Revolving Credit Facility And Term Loans (Schedule Of Defined Leverage Ratio, Including Interest Rate, Alternate Base Rate Loans, And Facility Fee) (Details)	12 Months Ended
	Dec. 31, 2017
45% Unsecured Term Loan Leverage Ratio [Member]
Debt Instrument [Line Items]
Spread over LIBOR	1.45%
45% Unsecured Term Loan Leverage Ratio [Member] | Maximum [Member]
Debt Instrument [Line Items]
Leverage ratio	45.00%
45% And 50% Unsecured Term Loan Leverage Ratio [Member]
Debt Instrument [Line Items]
Spread over LIBOR	1.55%
45% And 50% Unsecured Term Loan Leverage Ratio [Member] | Minimum [Member]
Debt Instrument [Line Items]
Leverage ratio	45.00%
45% And 50% Unsecured Term Loan Leverage Ratio [Member] | Maximum [Member]
Debt Instrument [Line Items]
Leverage ratio	50.00%
50% And 55% Unsecured Term Loan Leverage Ratio [Member]
Debt Instrument [Line Items]
Spread over LIBOR	1.65%
50% And 55% Unsecured Term Loan Leverage Ratio [Member] | Minimum [Member]
Debt Instrument [Line Items]
Leverage ratio	50.00%
50% And 55% Unsecured Term Loan Leverage Ratio [Member] | Maximum [Member]
Debt Instrument [Line Items]
Leverage ratio	55.00%
55% Unsecured Term Loan Leverage Ratio [Member]
Debt Instrument [Line Items]
Spread over LIBOR	1.95%
55% Unsecured Term Loan Leverage Ratio [Member] | Minimum [Member]
Debt Instrument [Line Items]
Leverage ratio	55.00%
2017 Credit Facility [Member]
Debt Instrument [Line Items]
Spread over LIBOR	1.20%
Facility Fee Basis Points	0.25%
2017 Credit Facility [Member] | 45% Unsecured Term Loan Leverage Ratio [Member]
Debt Instrument [Line Items]
Spread over LIBOR	1.25%
Facility Fee Basis Points	0.20%
2017 Credit Facility [Member] | 45% And 50% Unsecured Term Loan Leverage Ratio [Member]
Debt Instrument [Line Items]
Spread over LIBOR	1.30%
Facility Fee Basis Points	0.25%
2017 Credit Facility [Member] | 45% And 50% Unsecured Term Loan Leverage Ratio [Member] | Maximum [Member]
Debt Instrument [Line Items]
Leverage ratio	50.00%
2017 Credit Facility [Member] | 50% And 55% Unsecured Term Loan Leverage Ratio [Member]
Debt Instrument [Line Items]
Spread over LIBOR	1.35%
Facility Fee Basis Points	0.30%
2017 Credit Facility [Member] | 50% And 55% Unsecured Term Loan Leverage Ratio [Member] | Maximum [Member]
Debt Instrument [Line Items]
Leverage ratio	55.00%
2017 Credit Facility [Member] | 55% Unsecured Term Loan Leverage Ratio [Member]
Debt Instrument [Line Items]
Spread over LIBOR	1.60%
Facility Fee Basis Points	0.35%
2017 Credit Facility [Member] | Base Rate [Member] | 45% Unsecured Term Loan Leverage Ratio [Member]
Debt Instrument [Line Items]
Spread over LIBOR	0.25%
2017 Credit Facility [Member] | Base Rate [Member] | 45% And 50% Unsecured Term Loan Leverage Ratio [Member]
Debt Instrument [Line Items]
Spread over LIBOR	0.30%
2017 Credit Facility [Member] | Base Rate [Member] | 50% And 55% Unsecured Term Loan Leverage Ratio [Member]
Debt Instrument [Line Items]
Spread over LIBOR	0.35%
2017 Credit Facility [Member] | Base Rate [Member] | 55% Unsecured Term Loan Leverage Ratio [Member]
Debt Instrument [Line Items]
Spread over LIBOR	0.60%

Unsecured Revolving Credit Fa75

Unsecured Revolving Credit Facility And Term Loans (Schedule Of Unsecured Credit Rating And Facility Fee) (Details) - Unsecured Revolving Credit Facility [Member] - Mack-Cali Realty LP [Member]	12 Months Ended
	Dec. 31, 2017
No Ratings Or Less Than Baa3 [Member] | No Ratings Or Less Than BBB- [Member]
Line of Credit Facility [Line Items]
Unsecured Debt Ratings	No ratings or less than BBB-/Baa3
Interest Rate - Applicable Basis Points Above LIBOR	1.70%
Facility Fee Basis Points	0.35%
Baa3 [Member] | BBB- [Member]
Line of Credit Facility [Line Items]
Unsecured Debt Ratings	BBB- or Baa3 (current since January 2017 amendment)
Interest Rate - Applicable Basis Points Above LIBOR	1.30%
Facility Fee Basis Points	0.30%
Baa2 [Member] | BBB [Member]
Line of Credit Facility [Line Items]
Unsecured Debt Ratings	BBB or Baa2
Interest Rate - Applicable Basis Points Above LIBOR	1.10%
Facility Fee Basis Points	0.20%
Baa1 [Member] | BBB+ [Member]
Line of Credit Facility [Line Items]
Unsecured Debt Ratings	BBB+ or Baa1
Interest Rate - Applicable Basis Points Above LIBOR	1.00%
Facility Fee Basis Points	0.15%
A3 Or Higher [Member] | A- Or Higher [Member]
Line of Credit Facility [Line Items]
Unsecured Debt Ratings	A- or A3 or higher
Interest Rate - Applicable Basis Points Above LIBOR	0.925%
Facility Fee Basis Points	0.125%

Unsecured Revolving Credit Fa76

Unsecured Revolving Credit Facility And Term Loans (Schedule Of Interest Rate On Outstanding Borrowings Payable) (Details) - 2016 Term Loan [Member]	12 Months Ended
	Dec. 31, 2017
Line of Credit Facility [Line Items]
Interest Rate - Applicable Basis Points Above LIBOR	1.40%
Mack-Cali Realty LP [Member] | No Ratings Or Less Than Baa3 [Member] | No Ratings Or Less Than BBB- [Member]
Line of Credit Facility [Line Items]
Unsecured Debt Ratings	No ratings or less than BBB-/Baa3
Interest Rate - Applicable Basis Points Above LIBOR	1.85%
Mack-Cali Realty LP [Member] | Baa3 [Member] | BBB- [Member]
Line of Credit Facility [Line Items]
Unsecured Debt Ratings	BBB- or Baa3 (current interest rate based on Company's election)
Interest Rate - Applicable Basis Points Above LIBOR	1.40%
Mack-Cali Realty LP [Member] | Baa2 [Member] | BBB [Member]
Line of Credit Facility [Line Items]
Unsecured Debt Ratings	BBB or Baa2
Interest Rate - Applicable Basis Points Above LIBOR	1.15%
Mack-Cali Realty LP [Member] | Baa1 [Member] | BBB+ [Member]
Line of Credit Facility [Line Items]
Unsecured Debt Ratings	BBB+ or Baa1
Interest Rate - Applicable Basis Points Above LIBOR	1.00%
Mack-Cali Realty LP [Member] | A3 Or Higher [Member] | A- Or Higher [Member]
Line of Credit Facility [Line Items]
Unsecured Debt Ratings	A- or A3 or higher
Interest Rate - Applicable Basis Points Above LIBOR	0.90%

Unsecured Revolving Credit Fa77

Unsecured Revolving Credit Facility And Term Loans (Schedule Of Defined Leverage Ratio) (Details)	12 Months Ended
	Dec. 31, 2017
45% Unsecured Term Loan Leverage Ratio [Member]
Debt Instrument [Line Items]
Spread over LIBOR	1.45%
45% Unsecured Term Loan Leverage Ratio [Member] | Maximum [Member]
Debt Instrument [Line Items]
Leverage ratio	45.00%
45% And 50% Unsecured Term Loan Leverage Ratio [Member]
Debt Instrument [Line Items]
Spread over LIBOR	1.55%
45% And 50% Unsecured Term Loan Leverage Ratio [Member] | Minimum [Member]
Debt Instrument [Line Items]
Leverage ratio	45.00%
45% And 50% Unsecured Term Loan Leverage Ratio [Member] | Maximum [Member]
Debt Instrument [Line Items]
Leverage ratio	50.00%
50% And 55% Unsecured Term Loan Leverage Ratio [Member]
Debt Instrument [Line Items]
Spread over LIBOR	1.65%
50% And 55% Unsecured Term Loan Leverage Ratio [Member] | Minimum [Member]
Debt Instrument [Line Items]
Leverage ratio	50.00%
50% And 55% Unsecured Term Loan Leverage Ratio [Member] | Maximum [Member]
Debt Instrument [Line Items]
Leverage ratio	55.00%
55% Unsecured Term Loan Leverage Ratio [Member]
Debt Instrument [Line Items]
Spread over LIBOR	1.95%
55% Unsecured Term Loan Leverage Ratio [Member] | Minimum [Member]
Debt Instrument [Line Items]
Leverage ratio	55.00%

Mortgages, Loans Payable And 78

Mortgages, Loans Payable And Other Obligations (Narrative) (Details)	12 Months Ended
	Dec. 31, 2017USD ($)propertyitem	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Debt Instrument [Line Items]
Cash paid for interest	$ 103,559,000	$ 122,414,000	$ 115,123,000
Interest capitalized	20,240,000	19,316,000	16,217,000
Total indebtedness	2,809,568,000
Adjusted total indebtedness	$ 2,826,110,000	$ 2,357,055,000
Total indebtedness, weighted average interest rate	3.93%	3.79%
Projects Under Development And Developable Land [Member]
Debt Instrument [Line Items]
Number of projects with encumbered company mortgages | item	5
Carrying value of encumbered properties	$ 435,000,000
Other Property [Member]
Debt Instrument [Line Items]
Number of properties with encumbered company mortgages | property	15
Carrying value of encumbered properties	$ 1,600,000,000
Unconsolidated Joint Venture [Member]
Debt Instrument [Line Items]
Interest capitalized	1,056,000	$ 5,055,000	$ 5,325,000
Revolving Credit Facility Borrowing And Other Variable Rate Mortgage Debt [Member]
Debt Instrument [Line Items]
Total indebtedness	$ 382,443,000	$ 481,282,000
Total indebtedness, weighted average interest rate	3.63%	2.93%
Fixed Rate Debt And Other Obligations [Member]
Debt Instrument [Line Items]
Total indebtedness	$ 2,443,667,000	$ 1,875,773,000
Total indebtedness, weighted average interest rate	3.98%	4.01%

Mortgages, Loans Payable And 79

Mortgages, Loans Payable And Other Obligations (Summary Of Mortgages, Loans Payable And Other Obligations) (Details)		12 Months Ended
		Dec. 31, 2017USD ($)propertyitem	Dec. 31, 2016USD ($)		Dec. 31, 2015USD ($)	Sep. 29, 2017USD ($)
Debt Instrument [Line Items]
Principal balance outstanding		$ 2,809,568,000	$ 2,340,009,000
Adjustment for unamortized debt discount		3,505,000
Secured Debt		1,418,135,000	888,585,000
Borrowings from revolving credit facility		$ 730,000,000	1,165,000,000		$ 334,000,000
Minimum [Member]
Debt Instrument [Line Items]
Percentage of interest in venture		12.50%
Maximum [Member]
Debt Instrument [Line Items]
Percentage of interest in venture		85.00%
Port Imperial 4/5 Hotel [Member] | Construction Loan [Member]
Debt Instrument [Line Items]
Number of extension options | item		2
Loan extension period		1 year
Extension fee		0.20%
250 Johnson Road [Member] | Construction Loan [Member]
Debt Instrument [Line Items]
Number of extension options | item		1
Loan extension period		1 year
Extension fee		0.25%
Portside 5/6 [Member] | Construction Loan [Member]
Debt Instrument [Line Items]
Number of extension options | item		2
Loan extension period		1 year
Extension fee		0.15%
Port Imperial South 11 [Member] | Construction Loan [Member]
Debt Instrument [Line Items]
Number of extension options | item		2
Loan extension period		1 year
Extension fee		0.15%
Worcester [Member] | Construction Loan [Member]
Debt Instrument [Line Items]
Number of extension options | item		2
Loan extension period		1 year
Extension fee		0.15%
Secured Debt [Member]
Debt Instrument [Line Items]
Principal balance outstanding		$ 1,426,111,000	896,055,000
Unamortized deferred financing costs		(7,976,000)	(7,470,000)
Total mortgages, loans payable and other obligations, net		$ 1,418,135,000	888,585,000
Secured Debt [Member] | Curtis Center [Member]
Debt Instrument [Line Items]
Property Name	[1]	Curtis Center
Lender	[1]	CCRE & PREFG
LIBOR	[1],[2]	LIBOR+5.91
Spread over LIBOR	[1]	5.91%
Principal balance outstanding			75,000,000	[1]		$ 75,000,000
Percentage of interest in venture		50.00%
Secured Debt [Member] | Chase II [Member]
Debt Instrument [Line Items]
Property Name	[3]	Chase II
Lender	[3]	Fifth Third Bank
LIBOR	[2],[3]	LIBOR+2.25
Spread over LIBOR	[3]	2.25%
Principal balance outstanding	[3]		34,708,000
Secured Debt [Member] | 23 Main Street [Member]
Debt Instrument [Line Items]
Property Name		23 Main Street
Lender		Berkadia CMBS
Effective rate	[2]	5.59%
Principal balance outstanding		$ 27,090,000	27,838,000
Loan maturity date		Sep. 1, 2018
Secured Debt [Member] | Port Imperial 4/5 Hotel [Member]
Debt Instrument [Line Items]
Property Name	[4]	Port Imperial 4/5 Hotel
Lender	[4]	Fifth Third Bank & Santander
LIBOR	[2],[4]	LIBOR+4.50
Spread over LIBOR	[4]	4.50%
Principal balance outstanding	[4]	$ 43,674,000	14,919,000
Loan maturity date	[4]	Oct. 6, 2018
Secured Debt [Member] | Port Imperial 4/5 Hotel [Member] | Construction Loan [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 94,000,000
Secured Debt [Member] | Harborside Plaza 5 [Member]
Debt Instrument [Line Items]
Property Name	[5]	Haborside Plaza 5
Lender	[5]	The Northwestern Mutual Life Insurance Co. & New York Life Insurance Co.
Effective rate	[2],[5]	6.84%
Principal balance outstanding	[5]	$ 209,257,000	213,640,000
Loan maturity date	[5]	Nov. 1, 2018
Borrowings from revolving credit facility		$ 8,400,000
Secured Debt [Member] | One River Center [Member]
Debt Instrument [Line Items]
Property Name	[6]	One River Center
Lender	[6]	Guardian Life Insurance Co.
Effective rate	[2],[6]	7.31%
Principal balance outstanding	[6]	$ 40,485,000	41,197,000
Loan maturity date	[6]	Feb. 1, 2019
Number of properties used to collateralized mortgage | property		3
Secured Debt [Member] | Park Square [Member]
Debt Instrument [Line Items]
Property Name		Park Square
Lender		Wells Fargo Bank N.A.
LIBOR	[2]	LIBOR+1.87
Spread over LIBOR		1.87%
Principal balance outstanding		$ 26,567,000	27,500,000
Loan maturity date		Apr. 10, 2019
Secured Debt [Member] | 250 Johnson Road [Member]
Debt Instrument [Line Items]
Property Name	[7]	250 Johnson
Lender	[7]	M&T Bank
LIBOR	[2],[7]	LIBOR+2.35
Spread over LIBOR	[7]	2.35%
Principal balance outstanding	[7]	$ 32,491,000	2,440,000
Loan maturity date	[7]	May 20, 2019
Secured Debt [Member] | 250 Johnson Road [Member] | Construction Loan [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 42,000,000
Secured Debt [Member] | Portside 5/6 [Member]
Debt Instrument [Line Items]
Property Name	[8]	Portside 5/6
Lender	[8]	Citizens Bank
LIBOR	[2],[8]	LIBOR+2.50
Spread over LIBOR	[8]	2.50%
Principal balance outstanding	[8]	$ 45,778,000
Loan maturity date	[8]	Sep. 29, 2019
Secured Debt [Member] | Portside 5/6 [Member] | Construction Loan [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 73,000,000
Secured Debt [Member] | Port Imperial South 11 [Member]
Debt Instrument [Line Items]
Property Name	[9]	Port Imperial South 11
Lender	[9]	JPMorgan Chase
LIBOR	[2],[9]	LIBOR+2.35
Spread over LIBOR	[9]	2.35%
Principal balance outstanding	[9]	$ 46,113,000	14,073,000
Loan maturity date	[9]	Nov. 24, 2019
Secured Debt [Member] | Port Imperial South 11 [Member] | Construction Loan [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 78,000,000
Secured Debt [Member] | Worcester [Member]
Debt Instrument [Line Items]
Property Name	[10]	Worcester
Lender	[10]	Citizens Bank
LIBOR	[2],[10]	LIBOR+2.50
Spread over LIBOR	[10]	2.50%
Principal balance outstanding	[10]	$ 37,821,000
Loan maturity date	[10]	Dec. 10, 2019
Secured Debt [Member] | Worcester [Member] | Construction Loan [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 58,000,000
Secured Debt [Member] | Monaco [Member]
Debt Instrument [Line Items]
Property Name	[11]	Monaco
Lender	[11]	The Northwestern Mutual Life Insurance Co.
Effective rate	[2],[11]	3.15%
Principal balance outstanding	[11]	$ 169,987,000
Loan maturity date	[11]	Feb. 1, 2021
Adjustment for unamortized debt discount		$ 5,000,000
Secured Debt [Member] | Port Imperial South 4/5 Retail [Member]
Debt Instrument [Line Items]
Property Name		Port Imperial South 4/5 Retail
Lender		American General Life & A/G PC
Effective rate	[2]	4.56%
Principal balance outstanding		$ 4,000,000	4,000,000
Loan maturity date		Dec. 1, 2021
Secured Debt [Member] | Chase At Overlook Ridge [Member]
Debt Instrument [Line Items]
Property Name		The Chase at Overlook Ridge
Lender		New York Community Bank
Effective rate	[2]	3.74%
Principal balance outstanding			72,500,000
Loan maturity date		Feb. 1, 2023
Secured Debt [Member] | Portside 7 [Member]
Debt Instrument [Line Items]
Property Name		Portside 7
Lender		CBRE Capital Markets/FreddieMac
Effective rate	[2]	3.57%
Principal balance outstanding		$ 58,998,000	58,998,000
Loan maturity date		Aug. 1, 2023
Secured Debt [Member] | Alterra I & II [Member]
Debt Instrument [Line Items]
Property Name		Alterra I & II
Lender		Capital One/FreddieMac
Effective rate	[2]	3.85%
Principal balance outstanding		$ 100,000,000
Loan maturity date		Feb. 1, 2024
Secured Debt [Member] | The Chase At Overlook Ridge And Chase II [Member]
Debt Instrument [Line Items]
Property Name		The Chase at Overlook Ridge and Chase II
Lender		New York Community Bank
Effective rate	[2]	3.74%
Principal balance outstanding		$ 135,750,000
Loan maturity date		Jan. 1, 2025
Secured Debt [Member] | 101 Hudson Street [Member]
Debt Instrument [Line Items]
Property Name		101 Hudson
Lender		Wells Fargo CMBS
Effective rate	[2]	3.20%
Principal balance outstanding		$ 250,000,000	250,000,000
Loan maturity date		Oct. 11, 2026
Secured Debt [Member] | Short Hills Portfolio [Member]
Debt Instrument [Line Items]
Property Name	[12]	Short Hills Portfolio
Lender	[12]	Wells Fargo CMBS
Effective rate	[2],[12]	4.15%
Principal balance outstanding	[12]	$ 124,500,000
Loan maturity date	[12]	Apr. 1, 2027
Secured Debt [Member] | 150 Main St [Member]
Debt Instrument [Line Items]
Property Name		150 Main St.
Lender		Natixis Real Estate Capital LLC
Effective rate	[2]	4.48%
Principal balance outstanding		$ 41,000,000	26,642,000
Loan maturity date		Aug. 5, 2027
Secured Debt [Member] | Port Imperial South 4/5 Garage [Member]
Debt Instrument [Line Items]
Property Name		Port Imperial South 4/5 Garage
Lender		American General Life & A/G PC
Effective rate	[2]	4.85%
Principal balance outstanding		$ 32,600,000	$ 32,600,000
Loan maturity date		Dec. 1, 2029
[1]	The Company owned a 50 percent tenants-in-common interest in the Curtis Center property. On September 29, 2017, the Company sold its equity interest to its joint venture partner, which included the retirement of this $75 million loan balance.
[2]	Reflects effective rate of debt, including deferred financing costs, comprised of the cost of terminated treasury lock agreements (if any), debt initiation costs, mark-to-market adjustment of acquired debt and other transaction costs, as applicable.
[3]	The Chase II construction loan was paid off on December 5, 2017 using the proceeds of a new combined mortgage loan secured by The Chase at Overlook Ridge and Chase II.
[4]	This construction loan has a maximum borrowing capacity of $94 million and provides, subject to certain conditions, two one-year extension options with a fee of 20 basis points for each year. See Note 12: Commitments and Contingencies - Construction Projects.
[5]	On January 8, 2018, the Company prepaid this loan in full upon payment of a fee of approximately $8.4 million using borrowings from the Company's unsecured revolving credit facility.
[6]	Mortgage is collateralized by the three properties comprising One River Center.
[7]	This construction loan has a maximum borrowing capacity of $42 million and provides, subject to certain conditions, a one-year extension option with a fee of 25 basis points. See Note 12: Commitments and Contingencies - Construction Projects.
[8]	This construction loan has a maximum borrowing capacity of $73 million and provides, subject to certain conditions, two one-year extension options with a fee of 15 basis points each year. See Note 12: Commitments and Contingencies - Construction Projects.
[9]	This construction loan has a maximum borrowing capacity of $78 million and provides, subject to certain conditions, two one-year extension options with a fee of 15 basis points each year. See Note 12: Commitments and Contingencies - Construction Projects.
[10]	This construction loan has a maximum borrowing capacity of $58 million and provides, subject to certain conditions, two one-year extension options with a fee of 15 basis points each year. See Note 12: Commitments and Contingencies - Construction Projects.
[11]	This mortgage loan, which includes unamortized fair value adjustment of $5.0 million as of December 31, 2017, was assumed by the Company in April 2017 with the consolidation of all the interests in Monaco Towers. See Note 3: Recent Transactions - Consolidations.
[12]	This mortgage loan was obtained by the Company in March 2017 to partially fund the acquisition of the Short Hills/Madison portfolio.

Mortgages, Loans Payable And 80

Mortgages, Loans Payable And Other Obligatons (Schedule Of Principal Payments) (Details) - USD ($) $ in Thousands		Jan. 31, 2018	Dec. 31, 2017
Mortgages, Loans Payabes And Other Obligations [Line Items]
Scheduled Amortization, 2018	[1]		$ 6,977
Scheduled Amortization, 2019			665
Scheduled Amortization, 2020			2,903
Scheduled Amortization, 2021			3,227
Scheduled Amortization, 2022			3,284
Scheduled Amortization, Thereafter			10,642
Scheduled Amortization, Sub-total			27,698
Adjustment for unamortized debt discount/premium, net December 31, 2017			(3,505)
Scheduled Amortization, Unamortized mark to market			4,987
Unamortized deferred financing costs			(13,038)
Scheduled Amortization, Total			16,142
Principal Maturities, 2018	[1]		275,210
Principal Maturities, 2019			576,489
Principal Maturities, 2020			325,000
Principal Maturities, 2021			318,800
Principal Maturities, 2022			300,000
Principal Maturities, Thereafter			997,927
Principal Maturities, Sub-total			2,793,426
Principal Maturities, Total			2,793,426
Total, 2018	[1]		282,187
Total, 2019			577,154
Total, 2020			327,903
Total, 2021			322,027
Total, 2022			303,284
Total, Thereafter			1,008,569
Total, Sub-total			2,821,124
Adjustment for unamortized debt discount/premium, net December 31, 2017			(3,505)
Total, Unamortized mark to market			4,987
Total, Unamortized deferred financing costs			(13,038)
Total senior unsecured notes, net			$ 2,809,568
Subsequent Event [Member]
Mortgages, Loans Payabes And Other Obligations [Line Items]
Mortgage payable amount		$ 209,000
[1]	Includes a mortgage payable amount of approximately $209 million that the Company prepaid in January 2018.

Employee Benefit 401(k) Plans (

Employee Benefit 401(k) Plans (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Minimum employee subscription rate, percentage of compensation	1.00%
Maximum employee subscription rate, percentage of compensation	60.00%
Employee pre-tax contributions vested percentage	100.00%
Vesting rate	20.00%
Percentage vested after total service period	100.00%
Employees' vesting rights	Participants are always 100 percent vested in their pre-tax contributions and will begin vesting in any matching or profit sharing contributions made on their behalf after two years of service with the Company at a rate of 20 percent per year, becoming 100 percent vested after a total of six years of service with the Company.
Expenses for employee benefit plan	$ 1,055,000	$ 1,029,000	$ 970,000
Minimum [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Employer contribution vesting period	2 years
Maximum [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Employer contribution vesting period	6 years

Disclosure Of Fair Value Of A82

Disclosure Of Fair Value Of Assets And Liabilities (Narrative) (Details)	12 Months Ended
	Dec. 31, 2017USD ($)property	Dec. 31, 2016USD ($)property
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value of Company's long-term debt	$ 2,764,033,000	$ 2,308,488,000
Principal balance outstanding	$ 2,809,568,000	$ 2,340,009,000
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Office [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Number of properties held for sale | property		8
Aggregate carrying value		$ 39,700,000
Estimated expected sales proceeds		49,000,000
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Office [Member] | Parsippany, Paramus, Rochelle Park, Hamilton And Wall, New Jersey And White Plains, New York [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Number of properties held for sale | property	21
Aggregate carrying value	$ 171,600,000
Estimated expected sales proceeds	223,000,000
Disposal Group, Not Discontinued Operations [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Sales proceeds	399,332,000	664,481,000
Unrealized losses on rental properties held for sale	$ (12,331,000)	$ (7,665,000)

Commitments And Contingencies83

Commitments And Contingencies (Tax Abatement Agreements) (Narrative) (Details) - USD ($)	12 Months Ended			16 Months Ended	60 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Apr. 30, 2017	Apr. 30, 2022
Harborside Plaza 4-A [Member]
Commitments And Contingencies [Line Items]
Project period	20 years
Percentage of PILOT on project costs	2.00%
Total project costs	$ 49,500,000
Payments in lieu of property taxes (PILOT)	$ 1,100,000	$ 1,100,000	$ 990,000
Harborside Plaza 5 [Member]
Commitments And Contingencies [Line Items]
Project period	20 years
Percentage of PILOT on project costs	2.00%
Total project costs	$ 170,900,000
Payments in lieu of property taxes (PILOT)	$ 3,900,000	3,900,000	$ 3,400,000
Port Imperial South 4/5 Garage [Member]
Commitments And Contingencies [Line Items]
Project period	5 years
Port Imperial South 4/5 Garage [Member] | Tax Year 1 [Member]
Commitments And Contingencies [Line Items]
Annual percentage of cost for phase in	0.00%
Port Imperial South 4/5 Garage [Member] | Tax Year 2 [Member]
Commitments And Contingencies [Line Items]
Annual percentage of cost for phase in	80.00%
Port Imperial South 4/5 Garage [Member] | Tax Year 3 [Member]
Commitments And Contingencies [Line Items]
Annual percentage of cost for phase in	80.00%
Port Imperial South 4/5 Garage [Member] | Tax Year 4 [Member]
Commitments And Contingencies [Line Items]
Annual percentage of cost for phase in	80.00%
Port Imperial South 4/5 Garage [Member] | Tax Year 5 [Member]
Commitments And Contingencies [Line Items]
Annual percentage of cost for phase in	80.00%
Port Imperial South 1/3 Garage [Member]
Commitments And Contingencies [Line Items]
Project period	5 years
Percentage of taxes paid based on the land value	100.00%
Port Imperial South 1/3 Garage [Member] | Tax Year 1 [Member]
Commitments And Contingencies [Line Items]
Annual percentage of cost for phase in	0.00%
Port Imperial South 1/3 Garage [Member] | Tax Year 2 [Member]
Commitments And Contingencies [Line Items]
Annual percentage of cost for phase in	95.00%
Port Imperial South 1/3 Garage [Member] | Tax Year 3 [Member]
Commitments And Contingencies [Line Items]
Annual percentage of cost for phase in	95.00%
Port Imperial South 1/3 Garage [Member] | Tax Year 4 [Member]
Commitments And Contingencies [Line Items]
Annual percentage of cost for phase in	95.00%
Port Imperial South 1/3 Garage [Member] | Tax Year 5 [Member]
Commitments And Contingencies [Line Items]
Annual percentage of cost for phase in	95.00%
Port Imperial Hotel Development [Member]
Commitments And Contingencies [Line Items]
Project period	15 years
Percentage of PILOT on project costs	2.00%
Port Imperial South 11 Development [Member]
Commitments And Contingencies [Line Items]
Project period	15 years
Percentage of PILOT on gross revenues	10.00%
111 River Realty [Member]
Commitments And Contingencies [Line Items]
Payments in lieu of property taxes (PILOT)	$ 1,300,000	$ 600,000
Annual Payments in lieu of property taxes (PILOT)				$ 1,227,708
111 River Realty [Member] | Scenario, Forecast [Member]
Commitments And Contingencies [Line Items]
Annual Payments in lieu of property taxes (PILOT)					$ 1,406,064
Monaco [Member]
Commitments And Contingencies [Line Items]
Project period	10 years
Payments in lieu of property taxes (PILOT)	$ 1,643,522
Percentage of PILOT on gross revenues	10.00%

Commitments And Contingencies84

Commitments And Contingencies (Ground Lease Agreements) (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Commitments And Contingencies [Abstract]
Ground lease expense incurred	$ 2,600,000	$ 1,500,000	$ 406,000

Commitments And Contingencies85

Commitments And Contingencies (Construction Projects) (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)item	Dec. 31, 2016USD ($)item	Dec. 31, 2015USD ($)item	Sep. 30, 2016item
Commitments And Contingencies [Line Items]
Amount outstanding	$ 822,288	$ 634,069
Investment in unconsolidated joint ventures	36,060	$ 35,930	$ 78,027
XS Hotel Urban Renewal Associates LLC [Member]
Commitments And Contingencies [Line Items]
Percentage of interest in venture			90.00%
Costs of the project incurred	$ 101,700
Delivery date to tenant	second quarter 2018
Number of units | item			372
Total project costs	$ 139,400
City Square Project [Member]
Commitments And Contingencies [Line Items]
Costs of the project incurred	86,900
Total project costs	$ 92,700
City Square Project Phase One [Member]
Commitments And Contingencies [Line Items]
Delivery date to tenant	first quarter 2018
Number of units | item			237
City Square Project Phase Two [Member]
Commitments And Contingencies [Line Items]
Delivery date to tenant	third quarter 2018
Number of units | item				128
250 Johnson Road [Member]
Commitments And Contingencies [Line Items]
Costs of the project incurred	$ 53,900
Delivery date to tenant	first quarter 2018
Number of units | item		197
Total project costs	$ 58,700
Portside 5/6 [Member]
Commitments And Contingencies [Line Items]
Costs of the project incurred	$ 101,300
Delivery date to tenant	second quarter 2018
Number of units | item		296
Total project costs	$ 111,400
Port Imperial South 11 [Member]
Commitments And Contingencies [Line Items]
Costs of the project incurred	$ 83,600
Delivery date to tenant	second quarter 2018
Number of units | item	295
Total project costs	$ 125,000
Construction Loan [Member] | XS Hotel Urban Renewal Associates LLC [Member]
Commitments And Contingencies [Line Items]
Maximum borrowing capacity	94,000
Amount outstanding	43,700
Construction Loan [Member] | City Square Project [Member]
Commitments And Contingencies [Line Items]
Maximum borrowing capacity	58,000
Amount outstanding	37,800
Construction Loan [Member] | 250 Johnson Road [Member]
Commitments And Contingencies [Line Items]
Amount outstanding	32,500
Amount to fund	42,000
Construction Loan [Member] | Portside 5/6 [Member]
Commitments And Contingencies [Line Items]
Amount outstanding	45,800
Amount to fund	73,000
Construction Loan [Member] | Port Imperial South 11 [Member]
Commitments And Contingencies [Line Items]
Amount outstanding	46,100
Amount to fund	78,000
Development Property [Member] | Port Imperial South 11 [Member]
Commitments And Contingencies [Line Items]
Costs of the project incurred	37,500
Amount to fund	$ 47,000
Unconsolidated Joint Venture Hotel [Member]
Commitments And Contingencies [Line Items]
Number of units | item	350

Commitments And Contingencies86

Commitments And Contingencies (Changes In Executive Officers) (Narrative) (Details) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Messr Krug [Member] | Maximum [Member]
Commitments And Contingencies [Line Items]
Period for continuation of health insurance		2 years
Messr Krug [Member] | Scenario, Forecast [Member]
Commitments And Contingencies [Line Items]
Severance benefits	$ 1,312,500
Prorated 2018 target bonus amount	93,750
Messr Krug [Member] | Scenario, Forecast [Member] | Maximum [Member]
Commitments And Contingencies [Line Items]
COBRA payment	42,000
Messr DeLorenzo [Member] | Maximum [Member]
Commitments And Contingencies [Line Items]
Period for continuation of health insurance		18 months
Messr DeLorenzo [Member] | Scenario, Forecast [Member]
Commitments And Contingencies [Line Items]
Severance benefits	$ 500,000
Messr DeLorenzo [Member] | Scenario, Forecast [Member] | Mack-Cali Realty LP [Member]
Commitments And Contingencies [Line Items]
Partial accelerated vesting shares	9,111
Messr DeLorenzo [Member] | Scenario, Forecast [Member] | Maximum [Member]
Commitments And Contingencies [Line Items]
COBRA payment	$ 42,000
Time-Based Award [Member] | Messr Krug [Member] | Scenario, Forecast [Member] | Mack-Cali Realty LP [Member]
Commitments And Contingencies [Line Items]
Accelerated vesting shares	13,306
Performance Shares [Member] | Messr Krug [Member] | Scenario, Forecast [Member] | Mack-Cali Realty LP [Member]
Commitments And Contingencies [Line Items]
Accelerated vesting shares	18,665
Performance Shares [Member] | Messr DeLorenzo [Member] | Scenario, Forecast [Member] | Mack-Cali Realty LP [Member]
Commitments And Contingencies [Line Items]
Partial accelerated vesting shares	13,982

Commitments And Contingencies87

Commitments And Contingencies (Other) (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)property	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Aug. 31, 2017USD ($)
Commitments And Contingencies [Line Items]
Purchase price of property	$ 90,068	$ 121,582	$ 94,073
Notes Receivable 5.85 Interest Rate [Member]
Commitments And Contingencies [Line Items]
Notes receivable	$ 45,700			$ 44,700
Interest rate	5.85%
Purchase price of property	$ 73,000
Property Lock-Ups Expired [Member]
Commitments And Contingencies [Line Items]
Number of properties | property	80
Properties aggregate net book value	$ 1,000,000

Commitments And Contingencies88

Commitments And Contingencies (Future Minimum Rental Payments Of Ground Leases) (Details) $ in Thousands	Dec. 31, 2017USD ($)
Commitments And Contingencies [Abstract]
2,018	$ 2,465
2,019	2,471
2,020	2,487
2,021	2,487
2,022	2,487
2023 through 2084	212,534
Total	$ 224,931

Tenant Leases (Future Minimum R

Tenant Leases (Future Minimum Rentals To Be Received Under Non-Cancelable Operating Leases) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Property Subject to or Available for Operating Lease [Line Items]
2,018	$ 362,261
2,019	328,399
2,020	296,227
2,021	265,393
2,022	237,020
2023 and thereafter	951,264
Total	$ 2,440,564
Tenant Leases [Member]
Property Subject to or Available for Operating Lease [Line Items]
Operating leases with various expiration dates through year	Dec. 31, 2035
Multi-Family Properties [Member]
Property Subject to or Available for Operating Lease [Line Items]
Lease period	1 year

Redeemable Noncontrolling Int90

Redeemable Noncontrolling Interests (Narrative) (Details) - USD ($)	Mar. 10, 2017	Feb. 28, 2017	Feb. 27, 2017	Feb. 03, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Apr. 30, 2017
Redeemable Noncontrolling Interest [Line Items]
Expiration period					10 years
Minimum [Member]
Redeemable Noncontrolling Interest [Line Items]
Percentage of interest in venture					12.50%
Maximum [Member]
Redeemable Noncontrolling Interest [Line Items]
Percentage of interest in venture					85.00%
Mack-Cali Realty LP [Member]
Redeemable Noncontrolling Interest [Line Items]
Common unit distribution per unit declared					$ 0.75	$ 0.60	$ 0.60
Rockpoint [Member]
Redeemable Noncontrolling Interest [Line Items]
Pro rata distribution					10.90%
Estimated redemption value					$ 223,000,000
RRT [Member]
Redeemable Noncontrolling Interest [Line Items]
Pro rata distribution					89.10%
Series A Units [Member] | Mack-Cali Realty LP [Member]
Redeemable Noncontrolling Interest [Line Items]
Preferred units aggregate amount				$ 42,800,000
Preferred stock shares issued				42,800
Preferred units shares issued				42,800
Preferred unit annual rate				3.50%
Percentage of interest in venture				37.50%
Preferred unit in operating partnership				$ 1,000
Convertible preferred units				28.15
Expiration period				5 years
Shares converted to common units				1,204,820
Common unit distribution per unit declared				$ 35.52
Series A-1 Units [Member] | Mack-Cali Realty LP [Member]
Redeemable Noncontrolling Interest [Line Items]
Preferred stock shares issued		9,213
Preferred units shares issued		9,213						91
Preferred unit annual rate		3.50%
Percentage of interest in venture		13.80%
Preferred unit in operating partnership		$ 1,000
Convertible preferred units		27.936
Expiration period		5 years
Shares converted to common units		257,375
Common unit distribution per unit declared		$ 35.80
Monaco [Member] | Series A-1 Units [Member]
Redeemable Noncontrolling Interest [Line Items]
Percentage of interest in venture		13.80%
Monaco [Member] | Series A-1 Units [Member] | Mack-Cali Realty LP [Member]
Redeemable Noncontrolling Interest [Line Items]
Preferred units aggregate amount		$ 9,100,000
Preferred units shares issued		9,122						91
Percentage of interest in venture								71.20%
Investment Agreement [Member] | Rockpoint [Member]
Redeemable Noncontrolling Interest [Line Items]
Contributed equity value	$ 1,230,000,000
Incremental closing payments, Limited Partnership interest	$ 150,000,000
Investment Agreement [Member] | Rockpoint [Member] | Minimum [Member]
Redeemable Noncontrolling Interest [Line Items]
Incremental closing payments, Limited Partnership interest					$ 10,000,000
Investment Agreement [Member] | Rockpoint [Member] | Maximum [Member]
Redeemable Noncontrolling Interest [Line Items]
Contributed amount to obtain equity units			$ 300,000,000
RRLP [Member]
Redeemable Noncontrolling Interest [Line Items]
Annual return on the equity value					6.00%
RRLP [Member] | Rockpoint [Member]
Redeemable Noncontrolling Interest [Line Items]
Annual return					6.00%
Base return					5.00%
Internal rate of return					11.00%
Pro rata share					50.00%
RRLP [Member] | RRT [Member]
Redeemable Noncontrolling Interest [Line Items]
Base return					95.00%
Participation Rights [Member] | Maximum [Member]
Redeemable Noncontrolling Interest [Line Items]
Contributed amount to obtain equity units					$ 200,000,000

Redeemable Noncontrolling Int91

Redeemable Noncontrolling Interests (Schedule Of Changes In The Value Of The Redeemable Noncontrolling Interests) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Redeemable Noncontrolling Interest [Line Items]
Income Attributed to Noncontrolling Interests	$ (8,840)
Redemption Value Adjustment	(28,865)
Redeemable noncontrolling interests as of December 31, 2017	212,208
Redeemable Noncontrolling Interests [Member]
Redeemable Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interests Issued	202,013
Issuance Costs	(11,027)
Net	190,986
Income Attributed to Noncontrolling Interests	8,840
Distributions	(8,840)
Redemption Value Adjustment	21,222
Redeemable noncontrolling interests as of December 31, 2017	212,208
Redeemable Noncontrolling Interests [Member] | Series A And Series A-1 Preferred Units [Member]
Redeemable Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interests Issued	52,013
Issuance Costs	(464)
Net	51,549
Income Attributed to Noncontrolling Interests	1,631
Distributions	(1,631)
Redemption Value Adjustment	775
Redeemable noncontrolling interests as of December 31, 2017	52,324
Redeemable Noncontrolling Interests [Member] | Rockpoint [Member]
Redeemable Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interests Issued	150,000
Issuance Costs	(10,563)
Net	139,437
Income Attributed to Noncontrolling Interests	7,209
Distributions	(7,209)
Redemption Value Adjustment	20,447
Redeemable noncontrolling interests as of December 31, 2017	$ 159,884

Mack-Cali Realty Corporation 92

Mack-Cali Realty Corporation Stockholders' Equity And Mack-Cali Realty, L.P.'s Partners' Capital (Share/Unit Repurchase Program And Dividend Reinvestment And Stock Purchase Plan) (Narrative) (Details) - USD ($)	12 Months Ended		64 Months Ended
	Dec. 31, 2017	Dec. 31, 2012	Dec. 31, 2017
Stockolders Equity [Line Items]
Date share repurchase program was initiated	September 2,012
Capacity of share repurchase program	$ 150,000,000		$ 150,000,000
Shares purchased and retired			394,625
Aggregate cost of stock repurchased			$ 11,000,000
Capacity available for additional repurchase of outstanding common stock	$ 139,000,000		$ 139,000,000
Proceeds from sale of common units		$ 11,000,000
Dividend Reinvestment And Stock Purchase Plan [Member]
Stockolders Equity [Line Items]
Common stock reserved for future issuance	5,500,000		5,500,000
Monthly cash investment without restriction, maximum	$ 5,000

Mack-Cali Realty Corporation 93

Mack-Cali Realty Corporation Stockholders' Equity And Mack-Cali Realty, L.P.'s Partners' Capital (Stock Options Plans) (Narrative) (Details)	Jun. 05, 2015item$ / sharesshares	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)$ / sharesshares	May 31, 2013shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average remaining contractual life		7 years 4 months 24 days	8 years 4 months 24 days
Share price | $ / shares	$ 17.31
Share price - weighted average fair value of options granted | $ / shares				$ 3.06
Proceeds from stock options exercised | $		$ 0	$ 0	$ 0
Stock options expense | $		$ 464,000	$ 1,407,000	$ 432,000
Shares Under Options - Granted	800,000
Common stock trade share price | $ / shares	$ 25
Annual installments | item	3
Exercisable period		10 years
Common stock trading days		30 days
Three Equal Annual Installment [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Under Options - Granted	400,000
Common Stock Trades [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Under Options - Granted	400,000
2013 Incentive Stock Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reserved stocks for issuance					4,600,000
Shares Under Options - Granted				800,000

Mack-Cali Realty Corporation 94

Mack-Cali Realty Corporation Stockholders' Equity And Mack-Cali Realty, L.P.'s Partners' Capital (Restricted Stock Awards And Performance Share Units) (Narrative) (Details) - USD ($) $ in Millions	Jun. 05, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015		Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested restricted stock outstanding		108,318	145,278	136,220		346,946
Shares granted		59,985	74,622	41,337	[1]
Restricted Stock [Member] | 2013 Incentive Stock Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation vesting period		3 years
Shares granted	37,550.54
Restricted Stock [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation vesting period		1 year
Restricted Stock [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation vesting period		7 years
Unvested Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested restricted stock outstanding		95,801	120,245	98,669
Total Stockholder Return Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost		$ 0.9
Total unrecognized compensation cost, period of recognition		1 year 2 months 12 days
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost		$ 0.2
Total unrecognized compensation cost, period of recognition		4 months 24 days
Performance Shares [Member] | 2013 Incentive Stock Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	112,651.64
Performance period		3 years
Performance Shares [Member] | Minimum [Member] | 2013 Incentive Stock Plan [Member] | Three Years Period Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares vested	0.00%
Performance Shares [Member] | Maximum [Member] | 2013 Incentive Stock Plan [Member] | Three Years Period Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares vested	150.00%
[1]	Included in the 41,337 Restricted Stock Awards granted in 2015 were 37,551 awards granted to the Company's two executive officers, Mitchell E. Rudin and Michael J. DeMarco.

Mack-Cali Realty Corporation 95

Mack-Cali Realty Corporation Stockholders' Equity And Mack-Cali Realty, L.P.'s Partners' Capital (Long-Term Incentive Plan Awards) (Narrative) (Details) - USD ($) $ in Millions	Apr. 04, 2017	Mar. 08, 2016	Jun. 05, 2015	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted			800,000
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost				$ 0.2
Total unrecognized compensation cost, period of recognition				4 months 24 days
2016 LTIP Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividends paid, percent representing common unit of limited partnership interest				10.00%
Dividends paid, percent payable upon vesting of LTIP Unit				90.00%
Total unrecognized compensation cost				$ 11.1
Total unrecognized compensation cost, period of recognition				2 years 6 months
2016 TBV LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted				155,773
2016 OPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period				3 years
TSR percent				50.00%
2016 PBV LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted				496,781
2017 OPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period				3 years
TSR percent				36.00%
2017 PBV LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted				481,436
2017 TBV LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted				96,887
Messieur Rudin, Messieur DeMarco, And Messieur Tycher [Member] | 2016 LTIP Awards [Member] | Time-Based Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of the award		25.00%
Performance period				3 years
Messieur Rudin, Messieur DeMarco, And Messieur Tycher [Member] | 2016 LTIP Awards [Member] | Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining percent of the award		75.00%
Messieur Rudin, Messieur DeMarco, And Messieur Tycher [Member] | 2017 LTIP Awards [Member] | Time-Based Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of the award	25.00%
Messieur Rudin, Messieur DeMarco, And Messieur Tycher [Member] | 2017 LTIP Awards [Member] | Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining percent of the award	75.00%
Messieur Rudin, Messieur DeMarco, And Messieur Tycher [Member] | 2017 TBV LTIP Units [Member] | Time-Based Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period				3 years
Other Executive Officers [Member] | 2016 LTIP Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of the award		40.00%
Remaining percent of the award		60.00%
Other Executive Officers [Member] | 2017 LTIP Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of the award	40.00%
Remaining percent of the award	60.00%

Mack-Cali Realty Corporation 96

Mack-Cali Realty Corporation Stockholders' Equity And Mack-Cali Realty, L.P.'s Partners' Capital (Deferred Stock Compensation Plan For Directors) (Narrative) (Details) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Mack-Cali Realty Corporation Stockholders' Equity And Mack-Cali Realty, L.P.'s Partners' Capital [Abstract]
Maximum percentage of retainer fee that directors may defer	100.00%
Deferred stock units earned	19,728	14,274	19,702
Deferred stock units outstanding	210,738	193,711

Mack-Cali Realty Corporation 97

Mack-Cali Realty Corporation Stockholders' Equity And Mack-Cali Realty, L.P.'s Partners' Capital (Earnings Per Share/Unit) (Narrative) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Anti-dilutive securities excluded from the computation of earnings per share			405,000
Unvested restricted stock outstanding	108,318	145,278	136,220	346,946
Dividends declared per common share	$ 0.75	$ 0.60	$ 0.60
Mack-Cali Realty LP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Anti-dilutive securities excluded from the computation of earnings per share			405,000
Distribution declared per common unit	$ 0.75	$ 0.60	$ 0.60
Unvested Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested restricted stock outstanding	95,801	120,245	98,669
Unvested Restricted Stock [Member] | Mack-Cali Realty LP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested restricted stock outstanding	95,801	120,245	98,669

Mack-Cali Realty Corporation 98

Mack-Cali Realty Corporation Stockholders' Equity And Mack-Cali Realty, L.P.'s Partners' Capital (Schedule Of Stock Option Plans) (Details) - USD ($) $ / shares in Units, $ in Thousands	Jun. 05, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares Under Options - Granted	800,000
Outstanding stock option price range, lower range				$ 17.31
Outstanding stock option price range, upper range				$ 21.25
Outstanding stock option price		$ 17.31	$ 17.31
2013 Incentive Stock Plan [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares Under Options - Outstanding, beginning balance		800,000	805,000	10,000
Shares Under Options - Granted				800,000
Shares Under Options - Granted, Lapsed or Cancelled
Shares Under Options - Lapsed or Cancelled			(5,000)	(5,000)
Shares Under Options - Outstanding, ending balance		800,000	800,000	805,000
Shares Under Options - Options exercisable		666,666
Shares Under Options - Available for grant		2,069,064
Weighted Average Exercise Price - Outstanding, beginning balance		$ 17.31	$ 17.33	$ 33.36
Weighted Average Exercise Price - Granted				17.31
Weighted Average Exercise Price - Granted, Lapsed or Cancelled
Weighted Average Exercise Price - Lapsed or Cancelled			21.25	45.47
Weighted Average Exercise Price - Outstanding, ending balance		$ 17.31	$ 17.31	$ 17.33
Aggregate Intrinsic Value, Outstanding, beginning balance		$ 9,368	$ 4,843
Aggregate Intrinsic Value, Outstanding, ending balance		$ 3,400	$ 9,368	$ 4,843

Mack-Cali Realty Corporation 99

Mack-Cali Realty Corporation Stockholders' Equity And Mack-Cali Realty, L.P.'s Partners' Capital (Schedule Of Weighted Average Assumptions) (Details)	12 Months Ended
	Dec. 31, 2015
Time Vesting Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (in years)	6 years
Risk-free interest rate	2.04%
Volatility	29.00%
Dividend yield	3.50%
Price Vesting Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (in years)	5 years 9 months 18 days
Risk-free interest rate	1.96%
Volatility	29.00%
Dividend yield	3.50%

Mack-Cali Realty Corporation100

Mack-Cali Realty Corporation Stockholders' Equity And Mack-Cali Realty, L.P.'s Partners' Capital (Schedule Of Restricted Stock Awards) (Details)	12 Months Ended
	Dec. 31, 2017$ / sharesshares	Dec. 31, 2016$ / sharesshares	Dec. 31, 2015$ / sharesitemshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Outstanding, Beginning balance	145,278	136,220	346,946
Shares, Granted	59,985	74,622	41,337	[1]
Shares, Vested	(95,009)	(61,654)	(250,132)
Shares, Forfeited	(1,936)	(3,910)	(1,931)
Shares, Outstanding, Ending balance	108,318	145,278	136,220
Weighted-Average Grant-Date Fair Value, Outstanding beginning balance | $ / shares	$ 21.76	$ 19.36	$ 21.09
Weighted-Average Grant-Date Fair Value, Granted | $ / shares	27	23.79	17.51	[1]
Weighted-Average Grant-Date Fair Value, Vested | $ / shares	20.73	18.94	21.44
Weighted-Average Grant-Date Fair Value, Forfeited | $ / shares	25.83	21.58	20.31
Weighted-Average Grant-Date Fair Value, Outstanding ending balance | $ / shares	$ 25.49	$ 21.76	$ 19.36
Executive Officers [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of executive officers that were granted restricted stock awards | item			2
Messr Rudin And Messr DeMarco [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Granted			37,551
[1]	Included in the 41,337 Restricted Stock Awards granted in 2015 were 37,551 awards granted to the Company's two executive officers, Mitchell E. Rudin and Michael J. DeMarco.

Mack-Cali Realty Corporation101

Mack-Cali Realty Corporation Stockholders' Equity And Mack-Cali Realty, L.P.'s Partners' Capital (Earnings Per Share Tables - Basic Computation Of EPS) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stockolders Equity [Line Items]
Net income (loss)									$ 33,718	$ 130,294	$ (142,052)
Add: Noncontrolling interest in consolidated joint ventures									1,018	651	1,044
Add (deduct): Noncontrolling interest in Operating Partnership									(2,711)	(13,721)	15,256
Deduct: Redeemable noncontrolling interest									(8,840)
Deduct: Redemption value adjustment of redeemable noncontrolling interests									(17,951)
Net income (loss) available to common shareholders for basic earnings per share									$ 5,234	$ 117,224	$ (125,752)
Weighted average common shares									90,005	89,746	89,291
Net income (loss) available to common shareholders	$ (0.01)	$ 0.39	$ (0.44)	$ 0.11	$ 0.17	$ (0.10)	$ 0.54	$ 0.69	$ 0.06	$ 1.31	$ (1.41)
Mack-Cali Realty LP [Member]
Stockolders Equity [Line Items]
Net income (loss)									$ 33,718	$ 130,294	$ (142,052)
Add: Noncontrolling interest in consolidated joint ventures									1,018	651	1,044
Deduct: Redeemable noncontrolling interest									(8,840)
Deduct: Redemption value adjustment of redeemable noncontrolling interests									(20,025)
Net income (loss) available to common shareholders for basic earnings per share									$ 5,871	$ 130,945	$ (141,008)
Weighted average common units									100,410	100,245	100,222
Net income (loss) available to common shareholders	$ (0.01)	$ 0.39	$ (0.44)	$ 0.11	$ 0.17	$ (0.10)	$ 0.54	$ 0.69	$ 0.06	$ 1.31	$ (1.41)

Mack-Cali Realty Corporation102

Mack-Cali Realty Corporation Stockholders' Equity And Mack-Cali Realty, L.P.'s Partners' Capital (Earnings Per Share Tables - Diluted Computation Of EPS) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stockolders Equity [Line Items]
Net income (loss) available to common shareholders for basic earnings per share									$ 5,234	$ 117,224	$ (125,752)
Add (deduct): Noncontrolling interest in Operating Partnership									2,711	13,721	(15,256)
Deduct: Redeemable noncontrolling interest									(8,840)
Deduct: Redemption value adjustment of redeemable noncontrolling interest in Operating Partnership									(2,074)
Net income (loss) for diluted earnings per share									$ 5,871	$ 130,945	$ (141,008)
Weighted average common shares									100,703	100,498	100,222
Net income (loss) available to common shareholders	$ (0.01)	$ 0.39	$ (0.44)	$ 0.11	$ 0.17	$ (0.10)	$ 0.54	$ 0.69	$ 0.06	$ 1.30	$ (1.41)
Mack-Cali Realty LP [Member]
Stockolders Equity [Line Items]
Net income (loss) available to common shareholders for basic earnings per share									$ 5,871	$ 130,945	$ (141,008)
Deduct: Redeemable noncontrolling interest									$ (8,840)
Weighted average common unit									100,703	100,498	100,222
Net income (loss) available to common shareholders	$ (0.01)	$ 0.39	$ (0.44)	$ 0.11	$ 0.17	$ (0.10)	$ 0.54	$ 0.69	$ 0.06	$ 1.30	$ (1.41)

Mack-Cali Realty Corporation103

Mack-Cali Realty Corporation Stockholders' Equity And Mack-Cali Realty, L.P.'s Partners' Capital (Schedule Of Reconciliation Of Shares Used In Basic EPS Calculation To Shares Used In Diluted EPS Calculation) (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stockolders Equity [Line Items]
Basic EPS shares	90,005	89,746	89,291
Add: Operating Partnership - common units	10,405	10,499	10,931
Restricted Stock Awards	40	43
Stock Options	253	210
Diluted EPS Shares	100,703	100,498	100,222
Mack-Cali Realty LP [Member]
Stockolders Equity [Line Items]
Basic weighted average units outstanding	100,410	100,245	100,222
Restricted Stock Awards	40	43
Stock Options	253	210
Diluted weighted average units outstanding	100,703	100,498	100,222

Noncontrolling Interests In 104

Noncontrolling Interests In Subsidiaries (Narrative) (Details) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2017USD ($)shares	Dec. 31, 2017propertyshares	Dec. 31, 2016USD ($)
Noncontrolling Interest [Line Items]
Number of common shares received upon redemption of common units | shares		1
Rebalance of ownership percentage			$ 4.6
Percentage of noncontrolling interest		10.40%	10.50%
Cash consideration	$ 2
Issuance of common units | shares	99,412
Common unit value	$ 2.8
Participation Rights [Member]
Noncontrolling Interest [Line Items]
Number of properties | property		2
Excess net cash flow remaining after the distribution to the Company		50.00%
Internal rate of return		10.00%
Mack-Cali Realty LP [Member]
Noncontrolling Interest [Line Items]
Cash consideration	$ 2
Issuance of common units | shares	99,412
Common unit value	$ 2.8
Future Developments [Member] | Participation Rights [Member]
Noncontrolling Interest [Line Items]
Number of properties | property		1

Noncontrolling Interests In 105

Noncontrolling Interests In Subsidiaries (Changes In Noncontrolling Interests Of Subsidiaries) (Details) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Noncontrolling Interests In Subsidiaries [Abstract]
Balance, Beginning, Common Units	10,488,105	10,516,844	11,083,876
Redemption of common units for shares of common stock	(148,662)	(28,739)	(567,032)
Issuance of units, Common Units	99,412
Balance, Ending, Common Units	10,438,855	10,488,105	10,516,844
Balance, Beginning, LTIP Units	657,373
Issuance of units, LTIP Units	578,323	657,373
Cancellation of units	(4,819)
Balance, Ending, LTIP Units	1,230,877	657,373

Segment Reporting (Narrative) (

Segment Reporting (Narrative) (Details)	12 Months Ended
	Dec. 31, 2017USD ($)segment	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Segment Reporting Information [Line Items]
Number of business segments | segment	2
Foreign Locations [Member]
Segment Reporting Information [Line Items]
Revenue	$ 0	$ 0	$ 0
Long lived assets	$ 0	$ 0

Segment Reporting (Schedule Of

Segment Reporting (Schedule Of Selected Results Of Operations And Asset Information) (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Total revenues		$ 143,529	$ 160,018	$ 162,766	$ 149,887	$ 153,731	$ 157,517	$ 149,227	$ 152,923	$ 616,200	$ 613,398	$ 594,883
Total operating and interest expenses	[1]									396,306	415,351	425,151
Equity in earnings (loss) of unconsolidated joint ventures	[2]									(6,081)	18,788	(3,172)
Net operating income (loss)	[3]									213,813	216,835	166,560
Total assets		4,957,885				4,296,766				4,957,885	4,296,766
Total long-lived assets	[4]	4,291,126				3,616,534				4,291,126	3,616,534
Total investments in unconsolidated joint ventures		252,626				320,047				252,626	320,047
Impairment charge												197,919
Commercial And Other Real Estate [Member]
Segment Reporting Information [Line Items]
Total revenues										522,223	541,271	534,549
Total operating and interest expenses	[1]									238,055	263,663	262,768
Equity in earnings (loss) of unconsolidated joint ventures										1,644	23,796	5,118
Net operating income (loss)	[3]									285,812	301,404	276,899
Total assets		2,915,646				2,947,400				2,915,646	2,947,400
Total long-lived assets	[4]	2,613,815				2,621,467				2,613,815	2,621,467
Total investments in unconsolidated joint ventures		15,143				81,549				15,143	81,549
Multiple-Family Real Estate & Services [Member]
Segment Reporting Information [Line Items]
Total revenues	[5]									90,654	69,873	57,293
Total operating and interest expenses	[1],[5]									63,589	60,646	52,018
Equity in earnings (loss) of unconsolidated joint ventures	[5]									(7,725)	(5,008)	(8,290)
Net operating income (loss)	[3],[5]									19,340	4,219	(3,015)
Total assets	[5]	1,937,708				1,287,824				1,937,708	1,287,824
Total long-lived assets	[4],[5]	1,645,410				994,484				1,645,410	994,484
Total investments in unconsolidated joint ventures	[5]	237,321				238,498				237,321	238,498
Corporate & Other [Member]
Segment Reporting Information [Line Items]
Total revenues	[6]									3,323	2,254	3,041
Total operating and interest expenses	[1],[6]									94,662	91,042	110,365
Net operating income (loss)	[3],[6]									(91,339)	(88,788)	$ (107,324)
Total assets	[6]	104,531				61,542				104,531	61,542
Total long-lived assets	[4],[6]	31,901				$ 583				31,901	$ 583
Total investments in unconsolidated joint ventures	[6]	$ 162								$ 162
[1]	Total operating and interest expenses represent the sum of: real estate taxes; utilities; operating services; real estate services expenses; general and administrative, acquisition-related costs and interest expense (net of interest income). All interest expense, net of interest and other investment income, (including for property-level mortgages) is excluded from segment amounts and classified in Corporate & Other for all periods.
[2]	Amounts are net of amortization of basis differences of $792, $436 and $336 for the years ended December 31, 2017, 2016 and 2015, respectively.
[3]	Net operating income represents total revenues less total operating and interest expenses (as defined in Note "a"), plus equity in earnings (loss) of unconsolidated joint ventures, for the period.
[4]	Long-lived assets are comprised of net investment in rental property, unbilled rents receivable and goodwill.
[5]	Segment assets and operations were owned through a consolidated variable interest entity commencing in February 2017.
[6]	Corporate & Other represents all corporate-level items (including interest and other investment income, interest expense, non-property general and administrative expense) as well as intercompany eliminations necessary to reconcile to consolidated Company totals.

Segment Reporting (Schedule 108

Segment Reporting (Schedule Of Reconciliation Of Net Operating Income To Net Income Available To Common Shareholders) (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Net operating income	[1]									$ 213,813	$ 216,835	$ 166,560
Depreciation and amortization										(205,169)	(186,684)	(170,402)
Gain on change of control of interests											15,347
Realized gains (losses) and unrealized losses on disposition of rental property, net										2,364	109,666	53,261
Gain on sale of investment in unconsolidated joint venture										23,131	5,670	6,448
Loss from extinguishment of debt, net										(421)	(30,540)
Impairments												(197,919)
Net income (loss)		$ 5,411	$ 44,703	$ (39,125)	$ 22,729	$ 16,764	$ (9,605)	$ 54,366	$ 68,769	33,718	130,294	(142,052)
Noncontrolling interest in consolidated joint ventures										1,018	651	1,044
Noncontrolling interest in Operating Partnership										(2,711)	(13,721)	15,256
Redeemable noncontrolling interest										(8,840)
Net income (loss) available to common shareholders		2,582	38,054	(37,330)	19,879	15,181	(8,541)	48,393	62,191	23,185	117,224	(125,752)
Mack-Cali Realty LP [Member]
Segment Reporting Information [Line Items]
Net operating income										213,813	216,835	166,560
Depreciation and amortization										(205,169)	(186,684)	(170,402)
Gain on change of control of interests											15,347
Realized gains (losses) and unrealized losses on disposition of rental property, net										2,364	109,666	53,261
Gain on sale of investment in unconsolidated joint venture										23,131	5,670	6,448
Loss from extinguishment of debt, net										(421)	(30,540)
Impairments												(197,919)
Net income (loss)		5,411	44,703	(39,125)	22,729	16,764	(9,605)	54,366	68,769	33,718	130,294	(142,052)
Noncontrolling interest in consolidated joint ventures										1,018	651	1,044
Redeemable noncontrolling interest										(8,840)
Net income (loss) available to common shareholders		$ 2,881	$ 42,467	$ (41,626)	$ 22,174	$ 16,955	$ (9,540)	$ 54,055	$ 69,475	$ 25,896	$ 130,945	$ (141,008)
[1]	Net operating income represents total revenues less total operating and interest expenses (as defined in Note "a"), plus equity in earnings (loss) of unconsolidated joint ventures, for the period.

Related Party Transactions (Det

Related Party Transactions (Details)	12 Months Ended
	Dec. 31, 2017USD ($)ft²propertyitem	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Related Party Transaction [Line Items]
Lease revenue	$ 501,334,000	$ 506,877,000	$ 487,041,000
Mack [Member]
Related Party Transaction [Line Items]
Due from related parties	0	0
RG [Member]
Related Party Transaction [Line Items]
Related party revenue	$ 1,873,000	2,464,000	2,542,000
Leased Property [Member]
Related Party Transaction [Line Items]
Number of real estate properties | property	1
Lease expiration date	May 2,018
Number of lease options | item	2
Lease extension period	3 years
Leased Property [Member] | Mack [Member]
Related Party Transaction [Line Items]
Area Of Real Estate Property | ft²	7,034
Lease revenue	$ 187,000	$ 193,000	$ 204,000

Condensed Quarterly Financia110

Condensed Quarterly Financial Information (Summary Of Condensed Quarterly Financial Information) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Quarterly Financial Information [Abstract]
Total revenues	$ 143,529	$ 160,018	$ 162,766	$ 149,887	$ 153,731	$ 157,517	$ 149,227	$ 152,923	$ 616,200	$ 613,398	$ 594,883
Net income (loss)	5,411	44,703	(39,125)	22,729	16,764	(9,605)	54,366	68,769	33,718	130,294	(142,052)
Net income (loss) available to common shareholders	$ 2,582	$ 38,054	$ (37,330)	$ 19,879	$ 15,181	$ (8,541)	$ 48,393	$ 62,191	$ 23,185	$ 117,224	$ (125,752)
Basic earnings per common share:
Net income (loss) available to common shareholders	$ (0.01)	$ 0.39	$ (0.44)	$ 0.11	$ 0.17	$ (0.10)	$ 0.54	$ 0.69	$ 0.06	$ 1.31	$ (1.41)
Diluted earnings per common share:
Net income (loss) available to common shareholders	$ (0.01)	$ 0.39	$ (0.44)	$ 0.11	$ 0.17	$ (0.10)	$ 0.54	$ 0.69	$ 0.06	$ 1.30	$ (1.41)

Real Estate Investments And 111

Real Estate Investments And Accumulated Depreciation (Schedule Of Real Estate Investments And Accumulated Depreciation) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Related Encumbrances		$ 1,403,615
Initial Costs, Land		789,095
Initial Costs, Building and Improvements		3,553,425
Costs Capitalized Subsequent to Acquisition	[1]	760,324
Gross Amount at Which Carried at Close of Period, Land	[2]	786,789
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	4,316,055
Total		5,102,844	[3]	$ 4,804,867	$ 4,807,718	$ 4,958,179
Accumulated Depreciation		1,087,083	[4]	$ 1,332,073	$ 1,464,482	$ 1,414,305
Real Estate Aggregate Cost, Tax Purpose		$ 3,900,000
Office [Member] | One Bridge Plaza [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,981
Acquired		1,996
Initial Costs, Land		$ 2,439
Initial Costs, Building and Improvements		24,462
Costs Capitalized Subsequent to Acquisition	[1]	7,482
Gross Amount at Which Carried at Close of Period, Land	[2]	2,439
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	31,944
Total	[3]	34,383
Accumulated Depreciation	[4]	$ 16,885
Office [Member] | 2115 Linwood Avenue [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,981
Acquired		1,998
Initial Costs, Land		$ 474
Initial Costs, Building and Improvements		4,419
Costs Capitalized Subsequent to Acquisition	[1]	7,756
Gross Amount at Which Carried at Close of Period, Land	[2]	474
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	12,175
Total	[3]	12,649
Accumulated Depreciation	[4]	$ 5,035
Office [Member] | 150 J.F. Kennedy Parkway [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,980
Acquired		1,997
Initial Costs, Land		$ 12,606
Initial Costs, Building and Improvements		50,425
Costs Capitalized Subsequent to Acquisition	[1]	15,149
Gross Amount at Which Carried at Close of Period, Land	[2]	12,606
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	65,574
Total	[3]	78,180
Accumulated Depreciation	[4]	$ 30,833
Office [Member] | 75 Livingston Avenue [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,985
Acquired		2,009
Related Encumbrances		$ 4,478
Initial Costs, Land		1,900
Initial Costs, Building and Improvements		6,312
Costs Capitalized Subsequent to Acquisition	[1]	(1,725)
Gross Amount at Which Carried at Close of Period, Land	[2]	1,281
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	5,206
Total	[3]	6,487
Accumulated Depreciation	[4]	$ 1,387
Office [Member] | 51 J.F. Kennedy Parkway [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,988
Acquired		2,017
Related Encumbrances		$ 69,393
Initial Costs, Land		5,873
Initial Costs, Building and Improvements		100,359
Gross Amount at Which Carried at Close of Period, Land	[2]	5,873
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	100,359
Total	[3]	106,232
Accumulated Depreciation	[4]	$ 3,115
Office [Member] | 101 J.F. Kennedy Parkway [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,981
Acquired		2,017
Related Encumbrances		$ 29,169
Initial Costs, Land		4,380
Initial Costs, Building and Improvements		59,730
Gross Amount at Which Carried at Close of Period, Land	[2]	4,380
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	59,730
Total	[3]	64,110
Accumulated Depreciation	[4]	$ 1,844
Office [Member] | 103 J.F. Kennedy Parkway [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,981
Acquired		2,017
Related Encumbrances		$ 24,852
Initial Costs, Land		3,158
Initial Costs, Building and Improvements		50,813
Gross Amount at Which Carried at Close of Period, Land	[2]	3,158
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	50,813
Total	[3]	53,971
Accumulated Depreciation	[4]	$ 1,555
Office [Member] | 111 River Street [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		2,002
Acquired		2,016
Initial Costs, Land		$ 204
Initial Costs, Building and Improvements		198,609
Costs Capitalized Subsequent to Acquisition	[1]	14,771
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	213,584
Total	[3]	213,584
Accumulated Depreciation	[4]	$ 8,680
Office [Member] | Harborside Plaza 1 [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,983
Acquired		1,996
Initial Costs, Land		$ 3,923
Initial Costs, Building and Improvements		51,013
Costs Capitalized Subsequent to Acquisition	[1]	27,936
Gross Amount at Which Carried at Close of Period, Land	[2]	3,923
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	78,949
Total	[3]	82,872
Accumulated Depreciation	[4]	$ 44,931
Office [Member] | Harborside Plaza 2 [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,990
Acquired		1,996
Initial Costs, Land		$ 17,655
Initial Costs, Building and Improvements		101,546
Costs Capitalized Subsequent to Acquisition	[1]	40,011
Gross Amount at Which Carried at Close of Period, Land	[2]	8,364
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	150,848
Total	[3]	159,212
Accumulated Depreciation	[4]	$ 64,754
Office [Member] | Harborside Plaza 3 [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,990
Acquired		1,996
Initial Costs, Land		$ 17,655
Initial Costs, Building and Improvements		101,878
Costs Capitalized Subsequent to Acquisition	[1]	39,678
Gross Amount at Which Carried at Close of Period, Land	[2]	8,363
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	150,848
Total	[3]	159,211
Accumulated Depreciation	[4]	$ 64,754
Office [Member] | Harborside Plaza 4A [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		2,000
Acquired		2,000
Initial Costs, Land		$ 1,244
Initial Costs, Building and Improvements		56,144
Costs Capitalized Subsequent to Acquisition	[1]	8,452
Gross Amount at Which Carried at Close of Period, Land	[2]	1,244
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	64,596
Total	[3]	65,840
Accumulated Depreciation	[4]	$ 29,121
Office [Member] | Harborside Plaza 5 [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		2,002
Acquired		2,002
Related Encumbrances		$ 209,180
Initial Costs, Land		6,218
Initial Costs, Building and Improvements		170,682
Costs Capitalized Subsequent to Acquisition	[1]	61,569
Gross Amount at Which Carried at Close of Period, Land	[2]	5,705
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	232,764
Total	[3]	238,469
Accumulated Depreciation	[4]	$ 98,606
Office [Member] | 101 Hudson Street [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,992
Acquired		2,005
Related Encumbrances		$ 248,261
Initial Costs, Land		45,530
Initial Costs, Building and Improvements		271,376
Costs Capitalized Subsequent to Acquisition	[1]	16,952
Gross Amount at Which Carried at Close of Period, Land	[2]	45,530
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	288,328
Total	[3]	333,858
Accumulated Depreciation	[4]	$ 93,337
Office [Member] | 100 Avenue At Port Imperial [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		2,016
Acquired		2,016
Initial Costs, Land		$ 350
Costs Capitalized Subsequent to Acquisition	[1]	4,205
Gross Amount at Which Carried at Close of Period, Land	[2]	471
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	4,084
Total	[3]	4,555
Accumulated Depreciation	[4]	$ 186
Office [Member] | 500 Avenue At Port Imperial [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		2,013
Acquired		2,013
Related Encumbrances		$ 36,260
Initial Costs, Land		13,099
Initial Costs, Building and Improvements		56,669
Costs Capitalized Subsequent to Acquisition	[1]	(20,540)
Gross Amount at Which Carried at Close of Period, Land	[2]	13,099
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	36,129
Total	[3]	49,228
Accumulated Depreciation	[4]	$ 3,982
Office [Member] | 700 Horizon Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		2,007
Acquired		2,007
Initial Costs, Land		$ 490
Initial Costs, Building and Improvements		43
Costs Capitalized Subsequent to Acquisition	[1]	16,663
Gross Amount at Which Carried at Close of Period, Land	[2]	865
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	16,331
Total	[3]	17,196
Accumulated Depreciation	[4]	$ 5,046
Office [Member] | 100 Overlook Center [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,988
Acquired		1,997
Initial Costs, Land		$ 2,378
Initial Costs, Building and Improvements		21,754
Costs Capitalized Subsequent to Acquisition	[1]	4,245
Gross Amount at Which Carried at Close of Period, Land	[2]	2,378
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	25,999
Total	[3]	28,377
Accumulated Depreciation	[4]	$ 12,960
Office [Member] | 5 Vaughn Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,987
Acquired		1,995
Initial Costs, Land		$ 657
Initial Costs, Building and Improvements		9,800
Costs Capitalized Subsequent to Acquisition	[1]	1,983
Gross Amount at Which Carried at Close of Period, Land	[2]	657
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	11,783
Total	[3]	12,440
Accumulated Depreciation	[4]	$ 6,547
Office [Member] | 333 Thornall Street [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,984
Acquired		2,015
Initial Costs, Land		$ 5,542
Initial Costs, Building and Improvements		40,762
Costs Capitalized Subsequent to Acquisition	[1]	2,344
Gross Amount at Which Carried at Close of Period, Land	[2]	5,542
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	43,106
Total	[3]	48,648
Accumulated Depreciation	[4]	$ 3,319
Office [Member] | 343 Thornall Street [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,991
Acquired		2,006
Initial Costs, Land		$ 6,027
Initial Costs, Building and Improvements		39,101
Costs Capitalized Subsequent to Acquisition	[1]	11,532
Gross Amount at Which Carried at Close of Period, Land	[2]	6,027
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	50,633
Total	[3]	56,660
Accumulated Depreciation	[4]	$ 14,840
Office [Member] | 101 Wood Avenue South [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,990
Acquired		2,016
Initial Costs, Land		$ 8,509
Initial Costs, Building and Improvements		72,738
Costs Capitalized Subsequent to Acquisition	[1]	692
Gross Amount at Which Carried at Close of Period, Land	[2]	7,384
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	74,555
Total	[3]	81,939
Accumulated Depreciation	[4]	$ 4,315
Office [Member] | 500 College Road East [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built	[5]	1,984
Acquired	[5]	1,998
Initial Costs, Land	[5]	$ 614
Initial Costs, Building and Improvements	[5]	20,626
Costs Capitalized Subsequent to Acquisition	[1],[5]	5,708
Gross Amount at Which Carried at Close of Period, Land	[2],[5]	614
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2],[5]	26,334
Total	[3],[5]	26,948
Accumulated Depreciation	[4],[5]	$ 13,152
Office [Member] | 581 Main Street [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,991
Acquired		1,997
Initial Costs, Land		$ 3,237
Initial Costs, Building and Improvements		12,949
Costs Capitalized Subsequent to Acquisition	[1]	24,191
Gross Amount at Which Carried at Close of Period, Land	[2]	8,115
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	32,262
Total	[3]	40,377
Accumulated Depreciation	[4]	$ 15,056
Office [Member] | 23 Main Street [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,977
Acquired		2,005
Related Encumbrances		$ 27,078
Initial Costs, Land		4,336
Initial Costs, Building and Improvements		19,544
Costs Capitalized Subsequent to Acquisition	[1]	13,944
Gross Amount at Which Carried at Close of Period, Land	[2]	4,336
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	33,488
Total	[3]	37,824
Accumulated Depreciation	[4]	$ 15,515
Office [Member] | One River Center, Building 1 [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,983
Acquired		2,004
Related Encumbrances		$ 10,362
Initial Costs, Land		3,070
Initial Costs, Building and Improvements		17,414
Costs Capitalized Subsequent to Acquisition	[1]	11,421
Gross Amount at Which Carried at Close of Period, Land	[2]	2,451
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	29,454
Total	[3]	31,905
Accumulated Depreciation	[4]	$ 9,154
Office [Member] | One River Center, Building 2 [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,983
Acquired		2,004
Related Encumbrances		$ 11,624
Initial Costs, Land		2,468
Initial Costs, Building and Improvements		15,043
Costs Capitalized Subsequent to Acquisition	[1]	4,101
Gross Amount at Which Carried at Close of Period, Land	[2]	2,452
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	19,160
Total	[3]	21,612
Accumulated Depreciation	[4]	$ 7,093
Office [Member] | One River Center, Building 3 [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,984
Acquired		2,004
Related Encumbrances		$ 18,472
Initial Costs, Land		4,051
Initial Costs, Building and Improvements		24,790
Costs Capitalized Subsequent to Acquisition	[1]	5,687
Gross Amount at Which Carried at Close of Period, Land	[2]	4,627
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	29,901
Total	[3]	34,528
Accumulated Depreciation	[4]	$ 10,588
Office [Member] | 3600 Route 66 [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,989
Acquired		1,995
Initial Costs, Land		$ 1,098
Initial Costs, Building and Improvements		18,146
Costs Capitalized Subsequent to Acquisition	[1]	11,471
Gross Amount at Which Carried at Close of Period, Land	[2]	1,098
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	29,617
Total	[3]	30,715
Accumulated Depreciation	[4]	$ 14,193
Office [Member] | 100 Schultz Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,989
Acquired		2,017
Costs Capitalized Subsequent to Acquisition	[1]	$ 8,743
Gross Amount at Which Carried at Close of Period, Land	[2]	1,953
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	6,790
Total	[3]	8,743
Accumulated Depreciation	[4]	$ 556
Office [Member] | 200 Schultz Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,989
Acquired		2,017
Costs Capitalized Subsequent to Acquisition	[1]	$ 10,443
Gross Amount at Which Carried at Close of Period, Land	[2]	2,184
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	8,259
Total	[3]	10,443
Accumulated Depreciation	[4]	$ 495
Office [Member] | 325 Columbia Parkway [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,987
Acquired		1,994
Initial Costs, Land		$ 1,564
Costs Capitalized Subsequent to Acquisition	[1]	18,368
Gross Amount at Which Carried at Close of Period, Land	[2]	1,564
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	18,368
Total	[3]	19,932
Accumulated Depreciation	[4]	$ 12,583
Office [Member] | 1 Giralda Farms [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,982
Acquired		2,017
Costs Capitalized Subsequent to Acquisition	[1]	$ 30,515
Gross Amount at Which Carried at Close of Period, Land	[2]	3,370
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	27,145
Total	[3]	30,515
Accumulated Depreciation	[4]	$ 1,014
Office [Member] | 7 Giralda Farms [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,997
Acquired		2,017
Costs Capitalized Subsequent to Acquisition	[1]	$ 43,066
Gross Amount at Which Carried at Close of Period, Land	[2]	5,402
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	37,664
Total	[3]	43,066
Accumulated Depreciation	[4]	$ 1,246
Office [Member] | 201 Littleton Road [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,979
Acquired		1,997
Initial Costs, Land		$ 2,407
Initial Costs, Building and Improvements		9,627
Costs Capitalized Subsequent to Acquisition	[1]	3,132
Gross Amount at Which Carried at Close of Period, Land	[2]	2,407
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	12,759
Total	[3]	15,166
Accumulated Depreciation	[4]	$ 6,416
Office [Member] | 4 Campus Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,983
Acquired		2,001
Initial Costs, Land		$ 5,213
Initial Costs, Building and Improvements		20,984
Costs Capitalized Subsequent to Acquisition	[1]	4,117
Gross Amount at Which Carried at Close of Period, Land	[2]	5,213
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	25,101
Total	[3]	30,314
Accumulated Depreciation	[4]	$ 10,513
Office [Member] | 6 Campus Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,983
Acquired		2,001
Initial Costs, Land		$ 4,411
Initial Costs, Building and Improvements		17,796
Costs Capitalized Subsequent to Acquisition	[1]	3,550
Gross Amount at Which Carried at Close of Period, Land	[2]	4,411
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	21,346
Total	[3]	25,757
Accumulated Depreciation	[4]	$ 9,177
Office [Member] | 7 Campus Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,982
Acquired		1,998
Initial Costs, Land		$ 1,932
Initial Costs, Building and Improvements		27,788
Costs Capitalized Subsequent to Acquisition	[1]	6,573
Gross Amount at Which Carried at Close of Period, Land	[2]	1,932
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	34,361
Total	[3]	36,293
Accumulated Depreciation	[4]	$ 17,234
Office [Member] | 8 Campus Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,987
Acquired		1,998
Initial Costs, Land		$ 1,865
Initial Costs, Building and Improvements		35,456
Costs Capitalized Subsequent to Acquisition	[1]	11,139
Gross Amount at Which Carried at Close of Period, Land	[2]	1,865
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	46,595
Total	[3]	48,460
Accumulated Depreciation	[4]	$ 20,169
Office [Member] | 9 Campus Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,983
Acquired		2,001
Initial Costs, Land		$ 3,277
Initial Costs, Building and Improvements		11,796
Costs Capitalized Subsequent to Acquisition	[1]	22,609
Gross Amount at Which Carried at Close of Period, Land	[2]	5,842
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	31,840
Total	[3]	37,682
Accumulated Depreciation	[4]	$ 12,352
Office [Member] | 2 Dryden Way [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,990
Acquired		1,998
Initial Costs, Land		$ 778
Initial Costs, Building and Improvements		420
Costs Capitalized Subsequent to Acquisition	[1]	110
Gross Amount at Which Carried at Close of Period, Land	[2]	778
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	530
Total	[3]	1,308
Accumulated Depreciation	[4]	$ 302
Office [Member] | 4 Gatehall Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,988
Acquired		2,000
Initial Costs, Land		$ 8,452
Initial Costs, Building and Improvements		33,929
Costs Capitalized Subsequent to Acquisition	[1]	5,302
Gross Amount at Which Carried at Close of Period, Land	[2]	8,452
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	39,231
Total	[3]	47,683
Accumulated Depreciation	[4]	$ 17,628
Office [Member] | 2 Hilton Court [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,991
Acquired		1,998
Initial Costs, Land		$ 1,971
Initial Costs, Building and Improvements		32,007
Costs Capitalized Subsequent to Acquisition	[1]	4,474
Gross Amount at Which Carried at Close of Period, Land	[2]	1,971
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	36,481
Total	[3]	38,452
Accumulated Depreciation	[4]	$ 18,874
Office [Member] | 1 Sylvan Way [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,989
Acquired		1,998
Initial Costs, Land		$ 1,689
Initial Costs, Building and Improvements		24,699
Costs Capitalized Subsequent to Acquisition	[1]	2,253
Gross Amount at Which Carried at Close of Period, Land	[2]	1,021
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	27,620
Total	[3]	28,641
Accumulated Depreciation	[4]	$ 13,301
Office [Member] | 3 Sylvan Way [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,988
Acquired		2,015
Initial Costs, Land		$ 5,590
Initial Costs, Building and Improvements		4,710
Costs Capitalized Subsequent to Acquisition	[1]	4,033
Gross Amount at Which Carried at Close of Period, Land	[2]	5,590
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	8,743
Total	[3]	14,333
Accumulated Depreciation	[4]	$ 280
Office [Member] | 5 Sylvan Way [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,989
Acquired		1,998
Initial Costs, Land		$ 1,160
Initial Costs, Building and Improvements		25,214
Costs Capitalized Subsequent to Acquisition	[1]	4,769
Gross Amount at Which Carried at Close of Period, Land	[2]	1,161
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	29,982
Total	[3]	31,143
Accumulated Depreciation	[4]	$ 13,950
Office [Member] | 7 Sylvan Way [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,987
Acquired		1,998
Initial Costs, Land		$ 2,084
Initial Costs, Building and Improvements		26,083
Costs Capitalized Subsequent to Acquisition	[1]	14,805
Gross Amount at Which Carried at Close of Period, Land	[2]	2,084
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	40,888
Total	[3]	42,972
Accumulated Depreciation	[4]	$ 14,057
Office [Member] | 5 Wood Hollow Road [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,979
Acquired		2,004
Initial Costs, Land		$ 5,302
Initial Costs, Building and Improvements		26,488
Costs Capitalized Subsequent to Acquisition	[1]	20,963
Gross Amount at Which Carried at Close of Period, Land	[2]	5,302
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	47,451
Total	[3]	52,753
Accumulated Depreciation	[4]	$ 19,473
Office [Member] | 721 Route 202/206 [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,989
Acquired		1,997
Initial Costs, Land		$ 6,730
Initial Costs, Building and Improvements		26,919
Costs Capitalized Subsequent to Acquisition	[1]	(5,309)
Gross Amount at Which Carried at Close of Period, Land	[2]	5,067
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	23,273
Total	[3]	28,340
Accumulated Depreciation	[4]	$ 12,109
Office [Member] | 100 Clearbrook Road [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,975
Acquired		1,997
Initial Costs, Land		$ 220
Initial Costs, Building and Improvements		5,366
Costs Capitalized Subsequent to Acquisition	[1]	1,674
Gross Amount at Which Carried at Close of Period, Land	[2]	220
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	7,040
Total	[3]	7,260
Accumulated Depreciation	[4]	$ 3,422
Office [Member] | 101 Executive Boulevard [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,971
Acquired		1,997
Initial Costs, Land		$ 267
Initial Costs, Building and Improvements		5,838
Costs Capitalized Subsequent to Acquisition	[1]	(6,004)
Gross Amount at Which Carried at Close of Period, Land	[2]	101
Total	[3]	$ 101
Office [Member] | 1 Skyline Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,980
Acquired		1,997
Initial Costs, Land		$ 66
Initial Costs, Building and Improvements		1,711
Costs Capitalized Subsequent to Acquisition	[1]	210
Gross Amount at Which Carried at Close of Period, Land	[2]	66
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	1,921
Total	[3]	1,987
Accumulated Depreciation	[4]	$ 1,049
Office [Member] | 2 Skyline Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,987
Acquired		1,997
Initial Costs, Land		$ 109
Initial Costs, Building and Improvements		3,128
Costs Capitalized Subsequent to Acquisition	[1]	1,474
Gross Amount at Which Carried at Close of Period, Land	[2]	109
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	4,602
Total	[3]	4,711
Accumulated Depreciation	[4]	$ 2,696
Office [Member] | 7 Skyline Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,987
Acquired		1,998
Initial Costs, Land		$ 330
Initial Costs, Building and Improvements		13,013
Costs Capitalized Subsequent to Acquisition	[1]	2,929
Gross Amount at Which Carried at Close of Period, Land	[2]	330
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	15,942
Total	[3]	16,272
Accumulated Depreciation	[4]	$ 7,758
Office [Member] | 17 Skyline Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built	[5]	1,989
Acquired	[5]	1,997
Initial Costs, Building and Improvements	[5]	$ 7,269
Costs Capitalized Subsequent to Acquisition	[1],[5]	1,484
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2],[5]	8,753
Total	[3],[5]	8,753
Accumulated Depreciation	[4],[5]	$ 4,540
Office [Member] | 1 Barker Avenue [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,975
Acquired		1,997
Initial Costs, Land		$ 208
Initial Costs, Building and Improvements		9,629
Costs Capitalized Subsequent to Acquisition	[1]	3,248
Gross Amount at Which Carried at Close of Period, Land	[2]	207
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	12,878
Total	[3]	13,085
Accumulated Depreciation	[4]	$ 6,406
Office [Member] | 3 Barker Avenue [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,983
Acquired		1,997
Initial Costs, Land		$ 122
Initial Costs, Building and Improvements		7,864
Costs Capitalized Subsequent to Acquisition	[1]	2,117
Gross Amount at Which Carried at Close of Period, Land	[2]	122
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	9,981
Total	[3]	10,103
Accumulated Depreciation	[4]	$ 5,076
Office [Member] | 1 Executive Boulevard [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,982
Acquired		1,997
Initial Costs, Land		$ 1,104
Initial Costs, Building and Improvements		11,904
Costs Capitalized Subsequent to Acquisition	[1]	3,815
Gross Amount at Which Carried at Close of Period, Land	[2]	1,105
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	15,718
Total	[3]	16,823
Accumulated Depreciation	[4]	$ 7,750
Office [Member] | 3 Executive Boulevard [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,987
Acquired		1,997
Initial Costs, Land		$ 385
Initial Costs, Building and Improvements		6,256
Costs Capitalized Subsequent to Acquisition	[1]	1,817
Gross Amount at Which Carried at Close of Period, Land	[2]	385
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	8,073
Total	[3]	8,458
Accumulated Depreciation	[4]	$ 4,219
Office [Member] | 3 Odell Plaza [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,984
Acquired		2,003
Initial Costs, Land		$ 1,322
Initial Costs, Building and Improvements		4,777
Costs Capitalized Subsequent to Acquisition	[1]	2,332
Gross Amount at Which Carried at Close of Period, Land	[2]	1,322
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	7,109
Total	[3]	8,431
Accumulated Depreciation	[4]	$ 3,736
Office And Office/Flex Buildings [Member] | 600 Horizon Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		2,002
Acquired		2,002
Initial Costs, Building and Improvements		$ 7,549
Costs Capitalized Subsequent to Acquisition	[1]	1,189
Gross Amount at Which Carried at Close of Period, Land	[2]	685
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	8,053
Total	[3]	8,738
Accumulated Depreciation	[4]	$ 3,218
Office And Office/Flex Buildings [Member] | 11 Clearbrook Road [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,974
Acquired		1,997
Initial Costs, Land		$ 149
Initial Costs, Building and Improvements		2,159
Costs Capitalized Subsequent to Acquisition	[1]	578
Gross Amount at Which Carried at Close of Period, Land	[2]	149
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	2,737
Total	[3]	2,886
Accumulated Depreciation	[4]	$ 1,452
Office And Office/Flex Buildings [Member] | 75 Clearbrook Road [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,990
Acquired		1,997
Initial Costs, Land		$ 2,314
Initial Costs, Building and Improvements		4,716
Costs Capitalized Subsequent to Acquisition	[1]	57
Gross Amount at Which Carried at Close of Period, Land	[2]	2,314
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	4,773
Total	[3]	7,087
Accumulated Depreciation	[4]	$ 2,500
Office And Office/Flex Buildings [Member] | 125 Clearbrook Road [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		2,002
Acquired		2,002
Initial Costs, Land		$ 1,055
Initial Costs, Building and Improvements		3,676
Costs Capitalized Subsequent to Acquisition	[1]	(252)
Gross Amount at Which Carried at Close of Period, Land	[2]	1,055
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	3,424
Total	[3]	4,479
Accumulated Depreciation	[4]	$ 1,500
Office And Office/Flex Buildings [Member] | 150 Clearbrook Road [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,975
Acquired		1,997
Initial Costs, Land		$ 497
Initial Costs, Building and Improvements		7,030
Costs Capitalized Subsequent to Acquisition	[1]	2,156
Gross Amount at Which Carried at Close of Period, Land	[2]	497
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	9,186
Total	[3]	9,683
Accumulated Depreciation	[4]	$ 4,616
Office And Office/Flex Buildings [Member] | 175 Clearbrook Road [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,973
Acquired		1,997
Initial Costs, Land		$ 655
Initial Costs, Building and Improvements		7,473
Costs Capitalized Subsequent to Acquisition	[1]	953
Gross Amount at Which Carried at Close of Period, Land	[2]	655
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	8,426
Total	[3]	9,081
Accumulated Depreciation	[4]	$ 4,444
Office And Office/Flex Buildings [Member] | 200 Clearbrook Road [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,974
Acquired		1,997
Initial Costs, Land		$ 579
Initial Costs, Building and Improvements		6,620
Costs Capitalized Subsequent to Acquisition	[1]	1,667
Gross Amount at Which Carried at Close of Period, Land	[2]	579
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	8,287
Total	[3]	8,866
Accumulated Depreciation	[4]	$ 4,066
Office And Office/Flex Buildings [Member] | 250 Clearbrook Road [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,973
Acquired		1,997
Initial Costs, Land		$ 867
Initial Costs, Building and Improvements		8,647
Costs Capitalized Subsequent to Acquisition	[1]	2,434
Gross Amount at Which Carried at Close of Period, Land	[2]	867
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	11,081
Total	[3]	11,948
Accumulated Depreciation	[4]	$ 5,458
Office And Office/Flex Buildings [Member] | 50 Executive Boulevard [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,969
Acquired		1,997
Initial Costs, Land		$ 237
Initial Costs, Building and Improvements		2,617
Costs Capitalized Subsequent to Acquisition	[1]	540
Gross Amount at Which Carried at Close of Period, Land	[2]	237
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	3,157
Total	[3]	3,394
Accumulated Depreciation	[4]	$ 1,620
Office And Office/Flex Buildings [Member] | 77 Executive Boulevard [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,977
Acquired		1,997
Initial Costs, Land		$ 34
Initial Costs, Building and Improvements		1,104
Costs Capitalized Subsequent to Acquisition	[1]	177
Gross Amount at Which Carried at Close of Period, Land	[2]	34
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	1,281
Total	[3]	1,315
Accumulated Depreciation	[4]	$ 695
Office And Office/Flex Buildings [Member] | 85 Executive Boulevard [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,968
Acquired		1,997
Initial Costs, Land		$ 155
Initial Costs, Building and Improvements		2,507
Costs Capitalized Subsequent to Acquisition	[1]	538
Gross Amount at Which Carried at Close of Period, Land	[2]	155
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	3,045
Total	[3]	3,200
Accumulated Depreciation	[4]	$ 1,560
Office And Office/Flex Buildings [Member] | 300 Executive Boulevard [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,970
Acquired		1,997
Initial Costs, Land		$ 460
Initial Costs, Building and Improvements		3,609
Costs Capitalized Subsequent to Acquisition	[1]	302
Gross Amount at Which Carried at Close of Period, Land	[2]	460
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	3,911
Total	[3]	4,371
Accumulated Depreciation	[4]	$ 2,015
Office And Office/Flex Buildings [Member] | 350 Executive Boulevard [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,970
Acquired		1,997
Initial Costs, Land		$ 100
Initial Costs, Building and Improvements		1,793
Costs Capitalized Subsequent to Acquisition	[1]	175
Gross Amount at Which Carried at Close of Period, Land	[2]	100
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	1,968
Total	[3]	2,068
Accumulated Depreciation	[4]	$ 1,085
Office And Office/Flex Buildings [Member] | 399 Executive Boulevard [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,962
Acquired		1,997
Initial Costs, Land		$ 531
Initial Costs, Building and Improvements		7,191
Costs Capitalized Subsequent to Acquisition	[1]	163
Gross Amount at Which Carried at Close of Period, Land	[2]	531
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	7,354
Total	[3]	7,885
Accumulated Depreciation	[4]	$ 3,885
Office And Office/Flex Buildings [Member] | 400 Executive Boulevard [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,970
Acquired		1,997
Initial Costs, Land		$ 2,202
Initial Costs, Building and Improvements		1,846
Costs Capitalized Subsequent to Acquisition	[1]	1,140
Gross Amount at Which Carried at Close of Period, Land	[2]	2,202
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	2,986
Total	[3]	5,188
Accumulated Depreciation	[4]	$ 1,662
Office And Office/Flex Buildings [Member] | 500 Executive Boulevard [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,970
Acquired		1,997
Initial Costs, Land		$ 258
Initial Costs, Building and Improvements		4,183
Costs Capitalized Subsequent to Acquisition	[1]	384
Gross Amount at Which Carried at Close of Period, Land	[2]	258
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	4,567
Total	[3]	4,825
Accumulated Depreciation	[4]	$ 2,514
Office And Office/Flex Buildings [Member] | 525 Executive Boulevard [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,972
Acquired		1,997
Initial Costs, Land		$ 345
Initial Costs, Building and Improvements		5,499
Costs Capitalized Subsequent to Acquisition	[1]	900
Gross Amount at Which Carried at Close of Period, Land	[2]	345
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	6,399
Total	[3]	6,744
Accumulated Depreciation	[4]	$ 3,520
Office And Office/Flex Buildings [Member] | 1 Westchester Plaza [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,967
Acquired		1,997
Initial Costs, Land		$ 199
Initial Costs, Building and Improvements		2,023
Costs Capitalized Subsequent to Acquisition	[1]	152
Gross Amount at Which Carried at Close of Period, Land	[2]	199
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	2,175
Total	[3]	2,374
Accumulated Depreciation	[4]	$ 1,156
Office And Office/Flex Buildings [Member] | 2 Westchester Plaza [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,968
Acquired		1,997
Initial Costs, Land		$ 234
Initial Costs, Building and Improvements		2,726
Costs Capitalized Subsequent to Acquisition	[1]	914
Gross Amount at Which Carried at Close of Period, Land	[2]	234
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	3,640
Total	[3]	3,874
Accumulated Depreciation	[4]	$ 1,806
Office And Office/Flex Buildings [Member] | 3 Westchester Plaza [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,969
Acquired		1,997
Initial Costs, Land		$ 655
Initial Costs, Building and Improvements		7,936
Costs Capitalized Subsequent to Acquisition	[1]	1,407
Gross Amount at Which Carried at Close of Period, Land	[2]	655
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	9,343
Total	[3]	9,998
Accumulated Depreciation	[4]	$ 4,541
Office And Office/Flex Buildings [Member] | 4 Westchester Plaza [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,969
Acquired		1,997
Initial Costs, Land		$ 320
Initial Costs, Building and Improvements		3,729
Costs Capitalized Subsequent to Acquisition	[1]	1,979
Gross Amount at Which Carried at Close of Period, Land	[2]	320
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	5,708
Total	[3]	6,028
Accumulated Depreciation	[4]	$ 2,825
Office And Office/Flex Buildings [Member] | 5 Westchester Plaza [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,969
Acquired		1,997
Initial Costs, Land		$ 118
Initial Costs, Building and Improvements		1,949
Costs Capitalized Subsequent to Acquisition	[1]	374
Gross Amount at Which Carried at Close of Period, Land	[2]	118
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	2,323
Total	[3]	2,441
Accumulated Depreciation	[4]	$ 1,247
Office And Office/Flex Buildings [Member] | 6 Westchester Plaza [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,968
Acquired		1,997
Initial Costs, Land		$ 164
Initial Costs, Building and Improvements		1,998
Costs Capitalized Subsequent to Acquisition	[1]	160
Gross Amount at Which Carried at Close of Period, Land	[2]	164
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	2,158
Total	[3]	2,322
Accumulated Depreciation	[4]	$ 1,124
Office And Office/Flex Buildings [Member] | 7 Westchester Plaza [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,972
Acquired		1,997
Initial Costs, Land		$ 286
Initial Costs, Building and Improvements		4,321
Costs Capitalized Subsequent to Acquisition	[1]	1,166
Gross Amount at Which Carried at Close of Period, Land	[2]	286
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	5,487
Total	[3]	5,773
Accumulated Depreciation	[4]	$ 2,575
Office And Office/Flex Buildings [Member] | 8 Westchester Plaza [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,971
Acquired		1,997
Initial Costs, Land		$ 447
Initial Costs, Building and Improvements		5,262
Costs Capitalized Subsequent to Acquisition	[1]	2,127
Gross Amount at Which Carried at Close of Period, Land	[2]	447
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	7,389
Total	[3]	7,836
Accumulated Depreciation	[4]	$ 3,709
Office And Office/Flex Buildings [Member] | 200 Saw Mill River Road [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,965
Acquired		1,997
Initial Costs, Land		$ 353
Initial Costs, Building and Improvements		3,353
Costs Capitalized Subsequent to Acquisition	[1]	745
Gross Amount at Which Carried at Close of Period, Land	[2]	353
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	4,098
Total	[3]	4,451
Accumulated Depreciation	[4]	$ 2,037
Office And Office/Flex Buildings [Member] | 4 Skyline Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,987
Acquired		1,997
Initial Costs, Land		$ 363
Initial Costs, Building and Improvements		7,513
Costs Capitalized Subsequent to Acquisition	[1]	3,071
Gross Amount at Which Carried at Close of Period, Land	[2]	363
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	10,584
Total	[3]	10,947
Accumulated Depreciation	[4]	$ 6,190
Office And Office/Flex Buildings [Member] | 5 Skyline Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,980
Acquired		2,001
Initial Costs, Land		$ 2,219
Initial Costs, Building and Improvements		8,916
Costs Capitalized Subsequent to Acquisition	[1]	1,841
Gross Amount at Which Carried at Close of Period, Land	[2]	2,219
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	10,757
Total	[3]	12,976
Accumulated Depreciation	[4]	$ 5,495
Office And Office/Flex Buildings [Member] | 6 Skyline Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,980
Acquired		2,001
Initial Costs, Land		$ 740
Initial Costs, Building and Improvements		2,971
Costs Capitalized Subsequent to Acquisition	[1]	1,295
Gross Amount at Which Carried at Close of Period, Land	[2]	740
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	4,266
Total	[3]	5,006
Accumulated Depreciation	[4]	$ 2,582
Office And Office/Flex Buildings [Member] | 8 Skyline Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,985
Acquired		1,997
Initial Costs, Land		$ 212
Initial Costs, Building and Improvements		4,410
Costs Capitalized Subsequent to Acquisition	[1]	777
Gross Amount at Which Carried at Close of Period, Land	[2]	212
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	5,187
Total	[3]	5,399
Accumulated Depreciation	[4]	$ 2,893
Office And Office/Flex Buildings [Member] | 10 Skyline Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,985
Acquired		1,997
Initial Costs, Land		$ 134
Initial Costs, Building and Improvements		2,799
Costs Capitalized Subsequent to Acquisition	[1]	812
Gross Amount at Which Carried at Close of Period, Land	[2]	134
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	3,611
Total	[3]	3,745
Accumulated Depreciation	[4]	$ 2,121
Office And Office/Flex Buildings [Member] | 11 Skyline Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built	[5]	1,989
Acquired	[5]	1,997
Initial Costs, Building and Improvements	[5]	$ 4,788
Costs Capitalized Subsequent to Acquisition	[1],[5]	763
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2],[5]	5,551
Total	[3],[5]	5,551
Accumulated Depreciation	[4],[5]	$ 2,741
Office And Office/Flex Buildings [Member] | 12 Skyline Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built	[5]	1,999
Acquired	[5]	1,999
Initial Costs, Land	[5]	$ 1,562
Initial Costs, Building and Improvements	[5]	3,254
Costs Capitalized Subsequent to Acquisition	[1],[5]	218
Gross Amount at Which Carried at Close of Period, Land	[2],[5]	1,320
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2],[5]	3,714
Total	[3],[5]	5,034
Accumulated Depreciation	[4],[5]	$ 1,790
Office And Office/Flex Buildings [Member] | 15 Skyline Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built	[5]	1,989
Acquired	[5]	1,997
Initial Costs, Building and Improvements	[5]	$ 7,449
Costs Capitalized Subsequent to Acquisition	[1],[5]	1,749
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2],[5]	9,198
Total	[3],[5]	9,198
Accumulated Depreciation	[4],[5]	$ 4,220
Office And Office/Flex Buildings [Member] | 100 Corporate Boulevard [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,987
Acquired		1,997
Initial Costs, Land		$ 602
Initial Costs, Building and Improvements		9,910
Costs Capitalized Subsequent to Acquisition	[1]	1,334
Gross Amount at Which Carried at Close of Period, Land	[2]	602
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	11,244
Total	[3]	11,846
Accumulated Depreciation	[4]	$ 5,973
Office And Office/Flex Buildings [Member] | 200 Corporate Boulevard South [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,990
Acquired		1,997
Initial Costs, Land		$ 502
Initial Costs, Building and Improvements		7,575
Costs Capitalized Subsequent to Acquisition	[1]	3,116
Gross Amount at Which Carried at Close of Period, Land	[2]	502
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	10,691
Total	[3]	11,193
Accumulated Depreciation	[4]	$ 5,159
Office And Office/Flex Buildings [Member] | 4 Executive Plaza [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,986
Acquired		1,997
Initial Costs, Land		$ 584
Initial Costs, Building and Improvements		6,134
Costs Capitalized Subsequent to Acquisition	[1]	995
Gross Amount at Which Carried at Close of Period, Land	[2]	584
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	7,129
Total	[3]	7,713
Accumulated Depreciation	[4]	$ 3,664
Office And Office/Flex Buildings [Member] | 6 Executive Plaza [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,987
Acquired		1,997
Initial Costs, Land		$ 546
Initial Costs, Building and Improvements		7,246
Costs Capitalized Subsequent to Acquisition	[1]	2,360
Gross Amount at Which Carried at Close of Period, Land	[2]	546
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	9,606
Total	[3]	10,152
Accumulated Depreciation	[4]	$ 4,942
Office And Office/Flex Buildings [Member] | 1 Odell Plaza [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,980
Acquired		1,997
Initial Costs, Land		$ 1,206
Initial Costs, Building and Improvements		6,815
Costs Capitalized Subsequent to Acquisition	[1]	2,367
Gross Amount at Which Carried at Close of Period, Land	[2]	1,206
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	9,182
Total	[3]	10,388
Accumulated Depreciation	[4]	$ 4,775
Office And Office/Flex Buildings [Member] | 5 Odell Plaza [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,983
Acquired		1,997
Initial Costs, Land		$ 331
Initial Costs, Building and Improvements		2,988
Costs Capitalized Subsequent to Acquisition	[1]	535
Gross Amount at Which Carried at Close of Period, Land	[2]	331
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	3,523
Total	[3]	3,854
Accumulated Depreciation	[4]	$ 1,990
Office And Office/Flex Buildings [Member] | 7 Odell Plaza [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,984
Acquired		1,997
Initial Costs, Land		$ 419
Initial Costs, Building and Improvements		4,418
Costs Capitalized Subsequent to Acquisition	[1]	1,366
Gross Amount at Which Carried at Close of Period, Land	[2]	419
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	5,784
Total	[3]	6,203
Accumulated Depreciation	[4]	$ 2,886
Office And Office/Flex Buildings [Member] | 419 West Avenue [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,986
Acquired		1,997
Initial Costs, Land		$ 4,538
Initial Costs, Building and Improvements		9,246
Costs Capitalized Subsequent to Acquisition	[1]	482
Gross Amount at Which Carried at Close of Period, Land	[2]	4,538
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	9,728
Total	[3]	14,266
Accumulated Depreciation	[4]	$ 5,060
Office And Office/Flex Buildings [Member] | 500 West Avenue [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,988
Acquired		1,997
Initial Costs, Land		$ 415
Initial Costs, Building and Improvements		1,679
Costs Capitalized Subsequent to Acquisition	[1]	646
Gross Amount at Which Carried at Close of Period, Land	[2]	415
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	2,325
Total	[3]	2,740
Accumulated Depreciation	[4]	$ 1,098
Office And Office/Flex Buildings [Member] | 550 West Avenue [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,990
Acquired		1,997
Initial Costs, Land		$ 1,975
Initial Costs, Building and Improvements		3,856
Costs Capitalized Subsequent to Acquisition	[1]	133
Gross Amount at Which Carried at Close of Period, Land	[2]	1,975
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	3,989
Total	[3]	5,964
Accumulated Depreciation	[4]	$ 2,065
Office And Office/Flex Buildings [Member] | 600 West Avenue [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,999
Acquired		1,999
Initial Costs, Land		$ 2,305
Initial Costs, Building and Improvements		2,863
Costs Capitalized Subsequent to Acquisition	[1]	1,005
Gross Amount at Which Carried at Close of Period, Land	[2]	2,305
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	3,868
Total	[3]	6,173
Accumulated Depreciation	[4]	$ 1,611
Office And Office/Flex Buildings [Member] | 650 West Avenue [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,998
Acquired		1,998
Initial Costs, Land		$ 1,328
Costs Capitalized Subsequent to Acquisition	[1]	3,268
Gross Amount at Which Carried at Close of Period, Land	[2]	1,328
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	3,268
Total	[3]	4,596
Accumulated Depreciation	[4]	$ 1,613
Industrial/Warehouse Facilities [Member] | 1 Warehouse Lane [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built	[5]	1,957
Acquired	[5]	1,997
Initial Costs, Land	[5]	$ 3
Initial Costs, Building and Improvements	[5]	268
Costs Capitalized Subsequent to Acquisition	[1],[5]	208
Gross Amount at Which Carried at Close of Period, Land	[2],[5]	3
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2],[5]	476
Total	[3],[5]	479
Accumulated Depreciation	[4],[5]	$ 240
Industrial/Warehouse Facilities [Member] | 2 Warehouse Lane [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built	[5]	1,957
Acquired	[5]	1,997
Initial Costs, Land	[5]	$ 4
Initial Costs, Building and Improvements	[5]	672
Costs Capitalized Subsequent to Acquisition	[1],[5]	341
Gross Amount at Which Carried at Close of Period, Land	[2],[5]	4
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2],[5]	1,013
Total	[3],[5]	1,017
Accumulated Depreciation	[4],[5]	$ 444
Industrial/Warehouse Facilities [Member] | 3 Warehouse Lane [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built	[5]	1,957
Acquired	[5]	1,997
Initial Costs, Land	[5]	$ 21
Initial Costs, Building and Improvements	[5]	1,948
Costs Capitalized Subsequent to Acquisition	[1],[5]	363
Gross Amount at Which Carried at Close of Period, Land	[2],[5]	21
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2],[5]	2,311
Total	[3],[5]	2,332
Accumulated Depreciation	[4],[5]	$ 1,314
Industrial/Warehouse Facilities [Member] | 4 Warehouse Lane [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built	[5]	1,957
Acquired	[5]	1,997
Initial Costs, Land	[5]	$ 84
Initial Costs, Building and Improvements	[5]	13,393
Costs Capitalized Subsequent to Acquisition	[1],[5]	3,665
Gross Amount at Which Carried at Close of Period, Land	[2],[5]	85
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2],[5]	17,057
Total	[3],[5]	17,142
Accumulated Depreciation	[4],[5]	$ 8,441
Industrial/Warehouse Facilities [Member] | 5 Warehouse Lane [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built	[5]	1,957
Acquired	[5]	1,997
Initial Costs, Land	[5]	$ 19
Initial Costs, Building and Improvements	[5]	4,804
Costs Capitalized Subsequent to Acquisition	[1],[5]	884
Gross Amount at Which Carried at Close of Period, Land	[2],[5]	19
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2],[5]	5,688
Total	[3],[5]	5,707
Accumulated Depreciation	[4],[5]	$ 3,053
Industrial/Warehouse Facilities [Member] | 6 Warehouse Lane [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built	[5]	1,982
Acquired	[5]	1,997
Initial Costs, Land	[5]	$ 10
Initial Costs, Building and Improvements	[5]	4,419
Costs Capitalized Subsequent to Acquisition	[1],[5]	2,381
Gross Amount at Which Carried at Close of Period, Land	[2],[5]	10
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2],[5]	6,800
Total	[3],[5]	6,810
Accumulated Depreciation	[4],[5]	$ 3,246
Retail [Member] | 230 White Plains Road [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,984
Acquired		1,997
Initial Costs, Land		$ 124
Initial Costs, Building and Improvements		1,845
Costs Capitalized Subsequent to Acquisition	[1]	288
Gross Amount at Which Carried at Close of Period, Land	[2]	124
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	2,133
Total	[3]	2,257
Accumulated Depreciation	[4]	$ 1,045
Retail [Member] | 2 Executive Boulevard [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,986
Acquired		1,997
Initial Costs, Land		$ 89
Initial Costs, Building and Improvements		2,439
Costs Capitalized Subsequent to Acquisition	[1]	107
Gross Amount at Which Carried at Close of Period, Land	[2]	89
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	2,546
Total	[3]	2,635
Accumulated Depreciation	[4]	$ 1,324
Multi-Family Properties [Member] | RoseGarden Monaco, L.L.C. [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		2,011
Acquired		2,017
Related Encumbrances		$ 169,988
Initial Costs, Land		58,761
Initial Costs, Building and Improvements		240,870
Costs Capitalized Subsequent to Acquisition	[1]	11
Gross Amount at Which Carried at Close of Period, Land	[2]	58,761
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	240,881
Total	[3]	299,642
Accumulated Depreciation	[4]	$ 4,590
Multi-Family Properties [Member] | Richmond Court [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,997
Acquired		2,013
Initial Costs, Land		$ 2,992
Initial Costs, Building and Improvements		13,534
Costs Capitalized Subsequent to Acquisition	[1]	1,908
Gross Amount at Which Carried at Close of Period, Land	[2]	2,992
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	15,442
Total	[3]	18,434
Accumulated Depreciation	[4]	$ 1,417
Multi-Family Properties [Member] | Riverwatch Commons [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		1,995
Acquired		2,013
Initial Costs, Land		$ 4,169
Initial Costs, Building and Improvements		18,974
Costs Capitalized Subsequent to Acquisition	[1]	2,177
Gross Amount at Which Carried at Close of Period, Land	[2]	4,169
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	21,151
Total	[3]	25,320
Accumulated Depreciation	[4]	$ 1,951
Multi-Family Properties [Member] | Park Square [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		2,011
Acquired		2,013
Related Encumbrances		$ 26,526
Initial Costs, Land		4,000
Initial Costs, Building and Improvements		40,670
Costs Capitalized Subsequent to Acquisition	[1]	294
Gross Amount at Which Carried at Close of Period, Land	[2]	4,000
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	40,964
Total	[3]	44,964
Accumulated Depreciation	[4]	$ 4,192
Multi-Family Properties [Member] | Quarry Place At Tuckahoe [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		2,016
Acquired		2,016
Related Encumbrances		$ 40,367
Initial Costs, Land		5,585
Initial Costs, Building and Improvements		3,400
Costs Capitalized Subsequent to Acquisition	[1]	48,632
Gross Amount at Which Carried at Close of Period, Land	[2]	5,585
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	52,032
Total	[3]	57,617
Accumulated Depreciation	[4]	$ 1,163
Multi-Family Properties [Member] | Chase At Overlook Ridge [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		2,016
Acquired		2,016
Related Encumbrances		$ 74,988
Initial Costs, Land		11,072
Initial Costs, Building and Improvements		87,793
Costs Capitalized Subsequent to Acquisition	[1]	269
Gross Amount at Which Carried at Close of Period, Land	[2]	11,072
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	88,062
Total	[3]	99,134
Accumulated Depreciation	[4]	$ 4,577
Multi-Family Properties [Member] | The Chase II At Overlook Ridge [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		2,016
Acquired		2,016
Related Encumbrances		$ 59,697
Initial Costs, Land		10,755
Initial Costs, Building and Improvements		10,846
Costs Capitalized Subsequent to Acquisition	[1]	52,598
Gross Amount at Which Carried at Close of Period, Land	[2]	10,755
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	63,444
Total	[3]	74,199
Accumulated Depreciation	[4]	$ 1,390
Multi-Family Properties [Member] | Portside At Pier One [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		2,016
Acquired		2,016
Related Encumbrances		$ 58,566
Initial Costs, Building and Improvements		73,713
Costs Capitalized Subsequent to Acquisition	[1]	9
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	73,722
Total	[3]	73,722
Accumulated Depreciation	[4]	$ 3,908
Multi-Family Properties [Member] | Alterra At Overlook Ridge IA [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		2,004
Acquired		2,013
Related Encumbrances		$ 40,061
Initial Costs, Land		9,042
Initial Costs, Building and Improvements		50,671
Costs Capitalized Subsequent to Acquisition	[1]	956
Gross Amount at Which Carried at Close of Period, Land	[2]	9,042
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	51,627
Total	[3]	60,669
Accumulated Depreciation	[4]	$ 6,559
Multi-Family Properties [Member] | Alterra at Overlook Ridge II [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year Built		2,008
Acquired		2,013
Related Encumbrances		$ 59,309
Initial Costs, Land		12,055
Initial Costs, Building and Improvements		71,409
Costs Capitalized Subsequent to Acquisition	[1]	299
Gross Amount at Which Carried at Close of Period, Land	[2]	12,056
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	71,707
Total	[3]	83,763
Accumulated Depreciation	[4]	9,058
Projects Under Development And Developable Land [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Related Encumbrances		184,984
Initial Costs, Land		399,372
Initial Costs, Building and Improvements		677,593
Gross Amount at Which Carried at Close of Period, Land	[2]	399,372
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	677,593
Total	[3]	1,076,965
Accumulated Depreciation	[4]	33,278
Furniture, Fixtures And Equipment [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Costs Capitalized Subsequent to Acquisition	[1]	30,247
Gross Amount at Which Carried at Close of Period, Building and Improvements	[2]	30,247
Total	[3]	30,247
Accumulated Depreciation	[4]	$ 11,031
Buildings And Improvements [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Useful Live		40 years
[1]	These costs are net of impairments recorded, if any.
[2]	The aggregate cost for federal income tax purposes at December 31, 2017 was approximately $3.9 billion.
[3]	Properties identified as held for sale at December 31, 2017 are excluded.
[4]	Depreciation of buildings and improvements are calculated over lives ranging from the life of the lease to 40 years.
[5]	This property is located on land leased by the Company.

Real Estate Investments And 112

Real Estate Investments And Accumulated Depreciation (Schedule Of Changes In Rental Properties And Accumulated Depreciation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017		Dec. 31, 2016	Dec. 31, 2015
Real Estate Investments And Accumulated Depreciation [Abstract]
Rental Properties, Balance at beginning of year	$ 4,804,867		$ 4,807,718	$ 4,958,179
Rental Properties, Additions	1,179,365		819,535	219,227
Rental Properties, Rental property held for sale	(310,089)		(79,200)
Rental Properties, Properties sold	(538,424)		(695,837)	(82,015)
Rental Properties, Impairments				(255,849)
Rental Properties, Retirements/disposals	(32,875)		(47,349)	(31,824)
Rental Properties, Balance at end of year	5,102,844	[1]	4,804,867	4,807,718
Accumulated Depreciation, Balance at beginning of year	1,332,073		1,464,482	1,414,305
Accumulated Depreciation, Depreciation expense	154,343		151,569	147,447
Accumulated Depreciation, Rental property held for sale	(126,503)		(31,792)
Accumulated Depreciation, Properties sold	(217,625)		(204,837)	(7,517)
Accumulated Depreciation, Repurposed buildings	(22,330)
Accumulated Depreciation, Impairments				(57,929)
Accumulated Depreciation, Retirements/disposals	(32,875)		(47,349)	(31,824)
Accumulated Depreciation, Balance at end of year	$ 1,087,083	[2]	$ 1,332,073	$ 1,464,482
[1]	Properties identified as held for sale at December 31, 2017 are excluded.
[2]	Depreciation of buildings and improvements are calculated over lives ranging from the life of the lease to 40 years.

Mortgage Loans On Real Estate (

Mortgage Loans On Real Estate (Schedule Of Mortgage Loans On Real Estate) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Mortgage Loans on Real Estate [Line Items]
Face Amount of Mortgages or Maximum Available Credit	$ 44,695
Carrying Amount of Mortgages	$ 45,734
Borrower A [Member] | Land [Member]
Mortgage Loans on Real Estate [Line Items]
Interest Accrual Rate	5.85%
Interest Payment Rate	5.85%
Final Maturity Date	Jul. 21, 2019
Periodic Payment Terms	P&I
Face Amount of Mortgages or Maximum Available Credit	$ 44,695
Carrying Amount of Mortgages	$ 45,734

Mortgage Loans On Real Estat114

Mortgage Loans On Real Estate (Schedule Of Reconciliation On Real Estate) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Mortgage Loans on Real Estate [Abstract]
Beginning Balance
New mortgage loan	44,695
Accrued interest	1,039
Ending Balance	$ 45,734