COPT Defense Properties (CDP) 10-Q 28 Apr 17 2017 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2017	Apr. 21, 2017
Entity Information [Line Items]
Entity Registrant Name	CORPORATE OFFICE PROPERTIES TRUST
Entity Central Index Key	860,546
Document Type	10-Q
Document Period End Date	Mar. 31, 2017
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		99,433,410
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q1
Corporate Office Properties, L.P.
Entity Information [Line Items]
Entity Registrant Name	CORPORATE OFFICE PROPERTIES, L.P.
Entity Central Index Key	1,577,966
Document Type	10-Q
Document Period End Date	Mar. 31, 2017
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q1

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Properties, net:
Operating properties, net	$ 2,670,157	$ 2,671,831
Projects in development or held for future development	422,857	401,531
Total properties, net	3,093,014	3,073,362
Assets held for sale, net	41,391	94,654
Cash and cash equivalents	226,470	209,863
Restricted cash and marketable securities	6,439	8,193
Investment in unconsolidated real estate joint venture	25,417	25,548
Accounts receivable (net of allowance for doubtful accounts of $446 and $603, respectively)	29,431	34,438
Deferred rent receivable (net of allowance of $125 and $373, respectively)	89,410	90,219
Intangible assets on real estate acquisitions, net	73,748	78,351
Deferred leasing costs (net of accumulated amortization of $68,280 and $65,988, respectively)	40,753	41,214
Investing receivables	53,570	52,279
Prepaid expenses and other assets, net	59,723	72,764
Total assets	3,739,366	3,780,885
Liabilities:
Debt, net	1,903,657	1,904,001
Accounts payable and accrued expenses	83,107	108,682
Rents received in advance and security deposits	28,393	29,798
Dividends and distributions payable	31,131	31,335
Deferred revenue associated with operating leases	11,750	12,666
Redeemable preferred shares of beneficial interest at liquidation preference	0	26,583
Other liabilities	55,784	50,177
Total liabilities	2,113,822	2,163,242
Commitments and contingencies (Note 15)
Redeemable noncontrolling interests	23,676	22,979
Corporate Office Properties Trust’s shareholders’ equity:
Preferred Shares of beneficial interest at liquidation preference ($0.01 par value; 25,000,000 shares authorized, shares issued and outstanding of 6,900,000 at March 31, 2017 and December 31, 2016)	172,500	172,500
Common Shares of beneficial interest	994	985
Additional paid-in capital	2,136,369	2,116,581
Cumulative distributions in excess of net income	(774,445)	(765,276)
Accumulated other comprehensive loss	(370)	(1,731)
Total Corporate Office Properties Trust’s shareholders’ equity	1,535,048	1,523,059
Noncontrolling interests in subsidiaries:
Common units in COPLP	46,683	49,228
Preferred units in COPLP	8,800	8,800
Other consolidated entities	11,337	13,577
Noncontrolling interests in subsidiaries	66,820	71,605
Total equity	1,601,868	1,594,664
Total liabilities, redeemable noncontrolling interest and equity	3,739,366	3,780,885
Corporate Office Properties, L.P.
Properties, net:
Operating properties, net	2,670,157	2,671,831
Projects in development or held for future development	422,857	401,531
Total properties, net	3,093,014	3,073,362
Assets held for sale, net	41,391	94,654
Cash and cash equivalents	226,470	209,863
Restricted cash and marketable securities	2,288	2,756
Investment in unconsolidated real estate joint venture	25,417	25,548
Accounts receivable (net of allowance for doubtful accounts of $446 and $603, respectively)	29,431	34,438
Deferred rent receivable (net of allowance of $125 and $373, respectively)	89,410	90,219
Intangible assets on real estate acquisitions, net	73,748	78,351
Deferred leasing costs (net of accumulated amortization of $68,280 and $65,988, respectively)	40,753	41,214
Investing receivables	53,570	52,279
Prepaid expenses and other assets, net	59,723	72,764
Total assets	3,735,215	3,775,448
Liabilities:
Debt, net	1,903,657	1,904,001
Accounts payable and accrued expenses	83,107	108,682
Rents received in advance and security deposits	28,393	29,798
Dividends and distributions payable	31,131	31,335
Deferred revenue associated with operating leases	11,750	12,666
Redeemable preferred shares of beneficial interest at liquidation preference	0	26,583
Other liabilities	51,633	44,740
Total liabilities	2,109,671	2,157,805
Commitments and contingencies (Note 15)
Redeemable noncontrolling interests	23,676	22,979
Corporate Office Properties Trust’s shareholders’ equity:
Common Shares of beneficial interest	1,409,632	1,401,597
Accumulated other comprehensive loss	(446)	(1,854)
Total Corporate Office Properties Trust’s shareholders’ equity	1,590,486	1,581,043
Noncontrolling interests in subsidiaries:
Noncontrolling interests in subsidiaries	11,382	13,621
Total equity	1,601,868	1,594,664
Total liabilities, redeemable noncontrolling interest and equity	3,735,215	3,775,448
General Partner | Corporate Office Properties, L.P.
Corporate Office Properties Trust’s shareholders’ equity:
Preferred partners' capital accounts	172,500	172,500
Limited Partner | Corporate Office Properties, L.P.
Corporate Office Properties Trust’s shareholders’ equity:
Preferred partners' capital accounts	$ 8,800	$ 8,800

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Allowance for doubtful accounts - AR	$ 446	$ 603
Deferred rent receivable	125	373
Deferred leasing costs, accumulated amortization	$ 68,280	$ 65,988
Preferred Shares of beneficial interest, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred Shares of beneficial interest, shares authorized	25,000,000	25,000,000
Preferred Shares of beneficial interest, shares issued	6,900,000	6,900,000
Preferred Shares of beneficial interest, shares outstanding	6,900,000	6,900,000
Common Shares of beneficial interest, par value (in dollars per share)	$ 0.01	$ 0.01
Common Shares of beneficial interest, shares authorized	125,000,000	125,000,000
Common Shares of beneficial interest, shares issued	99,390,234	98,498,651
Common Shares of beneficial interest, shares outstanding	99,390,234	98,498,651
Redeemable Preferred Stock Liability Portion
Redeemable preferred units of general partner outstanding, in units	0	531,667
Preferred Shares of beneficial interest, par value (in dollars per share)	$ 0.01	$ 0.01
Corporate Office Properties, L.P.
Allowance for doubtful accounts - AR	$ 446	$ 603
Deferred rent receivable	125	373
Deferred leasing costs, accumulated amortization	$ 68,280	$ 65,988
Redeemable preferred units of general partner outstanding, in units	0	531,667
Corporate Office Properties, L.P. | General Partner
Common Shares of beneficial interest, shares outstanding	99,390,234	98,498,651
Preferred Units, Outstanding	6,900,000	6,900,000
Corporate Office Properties, L.P. | Limited Partner
Common Shares of beneficial interest, shares outstanding	3,405,391	3,590,391
Preferred Units, Outstanding	352,000	352,000

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Revenues
Rental revenue	$ 100,615	$ 105,382
Tenant recoveries and other real estate operations revenue	26,152	27,705
Construction contract and other service revenues	13,034	11,220
Total revenues	139,801	144,307
Expenses
Property operating expenses	48,519	51,875
Depreciation and amortization associated with real estate operations	33,059	34,527
Construction contract and other service expenses	12,486	10,694
Impairment losses	0	2,446
General, administrative and leasing expenses	8,611	11,883
Business development expenses and land carry costs	1,693	2,418
Total operating expenses	104,368	113,843
Operating income	35,433	30,464
Interest expense	(18,994)	(23,559)
Interest and other income	1,726	1,156
Gain on early extinguishment of debt	0	17
Income before equity in income of unconsolidated entities and income taxes	18,165	8,078
Equity in income of unconsolidated entities	725	10
Income tax (expense) benefit	(40)	8
Income before gain on sales of real estate	18,850	8,096
Gain on sales of real estate	4,238	0
Net income	23,088	8,096
Net income attributable to noncontrolling interests:
Common units in COPLP	(634)	(127)
Preferred units in COPLP	(165)	(165)
Other consolidated entities	(934)	(978)
Net income attributable to COPT	21,355	6,826
Preferred share/unit dividends/distributions	(3,180)	(3,552)
Net income attributable to COPT common shareholders	$ 18,175	$ 3,274
Earnings per common share:
Net income (loss) attributable to COPT common shareholders - basic (in dollars per share/unit)	$ 0.18	$ 0.03
Net income (loss) attributable to COPT common shareholders - diluted (in dollars per share/unit)	0.18	0.03
Dividends declared per common share/unit (in dollars per share)	$ 0.275	$ 0.275
Corporate Office Properties, L.P.
Revenues
Rental revenue	$ 100,615	$ 105,382
Tenant recoveries and other real estate operations revenue	26,152	27,705
Construction contract and other service revenues	13,034	11,220
Total revenues	139,801	144,307
Expenses
Property operating expenses	48,519	51,875
Depreciation and amortization associated with real estate operations	33,059	34,527
Construction contract and other service expenses	12,486	10,694
Impairment losses	0	2,446
General, administrative and leasing expenses	8,611	11,883
Business development expenses and land carry costs	1,693	2,418
Total operating expenses	104,368	113,843
Operating income	35,433	30,464
Interest expense	(18,994)	(23,559)
Interest and other income	1,726	1,156
Gain on early extinguishment of debt	0	17
Income before equity in income of unconsolidated entities and income taxes	18,165	8,078
Equity in income of unconsolidated entities	725	10
Income tax (expense) benefit	(40)	8
Income before gain on sales of real estate	18,850	8,096
Gain on sales of real estate	4,238	0
Net income	23,088	8,096
Net income attributable to noncontrolling interests:
Net income attributable to noncontrolling interests in consolidated entities	(934)	(979)
Net income attributable to COPT	22,154	7,117
Preferred share/unit dividends/distributions	(3,345)	(3,717)
Net income attributable to COPT common shareholders	$ 18,809	$ 3,400
Earnings per common share:
Net income (loss) attributable to COPT common shareholders - basic (in dollars per share/unit)	$ 0.18	$ 0.03
Net income (loss) attributable to COPT common shareholders - diluted (in dollars per share/unit)	0.18	0.03
Dividends declared per common share/unit (in dollars per share)	$ 0.275	$ 0.275

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Net income	$ 23,088	$ 8,096
Other comprehensive income (loss)
Unrealized gain (loss) on interest rate derivatives	224	(11,284)
Loss on interest rate derivatives included in interest expense	1,184	870
Other comprehensive income (loss)	1,408	(10,414)
Comprehensive income (loss)	24,496	(2,318)
Comprehensive income attributable to noncontrolling interests	(1,780)	(880)
Comprehensive income (loss) attributable to COPT	22,716	(3,198)
Corporate Office Properties, L.P.
Net income	23,088	8,096
Other comprehensive income (loss)
Unrealized gain (loss) on interest rate derivatives	224	(11,284)
Loss on interest rate derivatives included in interest expense	1,184	870
Other comprehensive income (loss)	1,408	(10,414)
Comprehensive income (loss)	24,496	(2,318)
Comprehensive income attributable to noncontrolling interests	(934)	(979)
Comprehensive income (loss) attributable to COPT	$ 23,562	$ (3,297)

Consolidated Statements of Equi

Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Preferred Shares	Common Shares	Additional Paid-in Capital	Cumulative Distributions in Excess of Net Income	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests	Corporate Office Properties, L.P.	Corporate Office Properties, L.P.Common Shares	Corporate Office Properties, L.P.Accumulated Other Comprehensive Income (Loss)	Corporate Office Properties, L.P.Noncontrolling Interests	Corporate Office Properties, L.P.Limited Partner	Corporate Office Properties, L.P.Limited PartnerPreferred Shares	Corporate Office Properties, L.P.General Partner	Corporate Office Properties, L.P.General PartnerPreferred Shares
Balance (COPT: 94,531,512 shares and 98,498,651 shares as of December 31, 2015 and 2016, respectively) at Dec. 31, 2015	$ 1,616,564	$ 199,083	$ 945	$ 2,004,507	$ (657,172)	$ (2,838)	$ 72,039	$ 1,616,564	$ 1,400,745	$ (2,985)	$ 10,921		$ 8,800		$ 199,083
Balance (preferred units) at Dec. 31, 2015													352,000		7,431,667
Balance (in units/ shares) at Dec. 31, 2015	94,531,512								98,208,903
Increase (Decrease) in Shareholders' Equity
Costs associated with common shares issued to the public	$ (5)			(5)				(5)	$ (5)
Share-based compensation issuance, net of redemptions (in units/shares)	129,869								129,869
Share-based compensation issuance, net of redemptions (COPT: 129,869 and 159,801 shares issued, net of redemptions for the three months ended March 31, 2016 and 2017, respectively)	$ 2,425		2	2,423				2,425	$ 2,425
Redemption of vested equity awards	(1,154)			(1,154)				(1,154)	(1,154)
Adjustments to noncontrolling interests resulting from changes in ownership of COPLP	0			54			(54)
Comprehensive income (loss)	(2,878)				6,826	(10,024)	320	(2,878)	3,400	(10,414)	419		$ 165		$ 3,552
Dividends / Distributions to owners of common and preferred units	(29,589)				(29,589)			(30,765)	(27,048)				$ (165)		$ (3,552)
Distributions to owners of common and preferred units in COPLP	(1,176)						(1,176)
Distributions to noncontrolling interests in subsidiaries	(4)						(4)	(4)			(4)
Adjustment to arrive at fair value of redeemable noncontrolling interests	$ (302)			(302)				(302)	$ (302)
Balance (in units/ shares) at Mar. 31, 2016	94,661,381								98,338,772
Balance (preferred units) at Mar. 31, 2016													352,000		7,431,667
Balance (COPT: 94,661,381 shares and 99,390,234 shares as of March 31, 2016 and 2017, respectively) at Mar. 31, 2016	$ 1,583,881	199,083	947	2,005,523	(679,935)	(12,862)	71,125	1,583,881	$ 1,378,061	(13,399)	11,336		$ 8,800		$ 199,083
Balance (COPT: 94,531,512 shares and 98,498,651 shares as of December 31, 2015 and 2016, respectively) at Dec. 31, 2016	$ 1,594,664	172,500	985	2,116,581	(765,276)	(1,731)	71,605	1,594,664	$ 1,401,597	(1,854)	13,621		$ 8,800		$ 172,500
Balance (preferred units) at Dec. 31, 2016												352,000	352,000	6,900,000	6,900,000
Balance (in units/ shares) at Dec. 31, 2016	98,498,651								102,089,042			3,590,391		98,498,651
Increase (Decrease) in Shareholders' Equity
Conversion of common units to common shares (185,000 shares)	$ 0		2	2,535			(2,537)
Issuance of common units resulting from common shares issued under at-the-market program (in units)									546,782
Issuance of common units resulting from common shares issued under at-the-market program (COPT: 546,782 shares for the three months ended March 31, 2017)	$ 18,222		5	18,217				18,222	$ 18,222
Share-based compensation issuance, net of redemptions (in units/shares)	159,801								159,801
Share-based compensation issuance, net of redemptions (COPT: 129,869 and 159,801 shares issued, net of redemptions for the three months ended March 31, 2016 and 2017, respectively)	$ 1,582		2	1,580				1,582	$ 1,582
Redemption of vested equity awards	(1,753)			(1,753)				(1,753)	(1,753)
Adjustments to noncontrolling interests resulting from changes in ownership of COPLP	0			(246)			246
Comprehensive income (loss)	23,929				21,355	1,361	1,213	23,929	18,809	1,408	367		$ 165		$ 3,180
Dividends / Distributions to owners of common and preferred units	(30,524)				(30,524)			(31,625)	(28,280)				$ (165)		$ (3,180)
Distributions to owners of common and preferred units in COPLP	(1,101)						(1,101)
Distributions to noncontrolling interests in subsidiaries	(2,606)						(2,606)	(2,606)			(2,606)
Adjustment to arrive at fair value of redeemable noncontrolling interests	$ (545)			(545)				(545)	$ (545)
Balance (in units/ shares) at Mar. 31, 2017	99,390,234								102,795,625			3,405,391		99,390,234
Balance (preferred units) at Mar. 31, 2017												352,000	352,000	6,900,000	6,900,000
Balance (COPT: 94,661,381 shares and 99,390,234 shares as of March 31, 2016 and 2017, respectively) at Mar. 31, 2017	$ 1,601,868	$ 172,500	$ 994	$ 2,136,369	$ (774,445)	$ (370)	$ 66,820	$ 1,601,868	$ 1,409,632	$ (446)	$ 11,382		$ 8,800		$ 172,500

Consolidated Statements of Equ7

Consolidated Statements of Equity (Parenthetical) - shares	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015
Balance (in units/ shares)	99,390,234	94,661,381	98,498,651	94,531,512
Conversion of common units to common shares (in units/ shares)	185,000
Share-based compensation issuance, net of redemptions (in units/shares)	159,801	129,869
Common Shares
Issuance of common units resulting from common shares issued under at-the-market program (in units)	546,782

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities
Revenues from real estate operations received	$ 133,895	$ 130,474
Construction contract and other service revenues received	23,527	7,747
Property operating expenses paid	(41,192)	(46,084)
Construction contract and other service expenses paid	(14,790)	(10,765)
General, administrative, leasing, business development and land carry costs paid	(14,275)	(12,175)
Interest expense paid	(19,549)	(21,386)
Lease incentives	(7,729)	(415)
Other	750	43
Net cash provided by operating activities	60,637	47,439
Cash flows from investing activities
Construction, development and redevelopment	(35,795)	(45,146)
Tenant improvements on operating properties	(6,916)	(6,388)
Other capital improvements on operating properties	(5,203)	(9,505)
Proceeds from dispositions of properties	52,596	5,452
Leasing costs paid	(2,042)	(1,593)
Other	(717)	1,121
Net cash provided by (used in) investing activities	1,923	(56,059)
Proceeds from debt
Revolving Credit Facility	0	88,500
Repayments of debt
Revolving Credit Facility	0	(25,000)
Scheduled principal amortization	(958)	(1,800)
Other debt repayments	(50)	(50)
Net proceeds from issuance of common shares/units	18,237	(5)
Redemption of preferred shares/units	(26,583)	0
Common share/unit dividends/distributions paid	(27,100)	(26,002)
Preferred share/unit dividends/distributions paid	(3,581)	(3,552)
Distributions paid to noncontrolling interests in COPLP	(1,156)	(1,171)
Redemption of vested equity awards	(1,753)	(1,154)
Distributions paid to redeemable noncontrolling interests	(407)	(13,848)
Other	(2,602)	(5,119)
Net cash (used in) provided by financing activities	(45,953)	10,799
Net increase in cash and cash equivalents	16,607	2,179
Cash and cash equivalents
Beginning of period	209,863	60,310
End of period	226,470	62,489
Reconciliation of net income to net cash provided by operating activities:
Net income	23,088	8,096
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	33,570	35,129
Impairment losses	0	2,446
(Gain) loss on interest rate derivatives	(454)	1,551
Amortization of deferred financing costs and net debt discounts	1,348	1,495
Increase in deferred rent receivable	(191)	(1,456)
Gain on sales of real estate	(4,238)	0
Share-based compensation	1,488	2,108
Other	(1,341)	(802)
Operating changes in assets and liabilities:
Decrease in accounts receivable	5,007	409
Decrease in restricted cash and marketable securities	2,043	15
Decrease in prepaid expenses and other assets, net	13,991	5,941
Decrease in accounts payable, accrued expenses and other liabilities	(12,269)	(3,802)
Decrease in rents received in advance and security deposits	(1,405)	(3,691)
Net cash provided by operating activities	60,637	47,439
Supplemental schedule of non-cash investing and financing activities:
Decrease in accrued capital improvements, leasing and other investing activity costs	(6,661)	(9,420)
Increase in property and redeemable noncontrolling interests in connection with property contributed in a joint venture	0	22,600
Decrease in redeemable noncontrolling interests and increase in other liabilities in connection with distribution payable to redeemable noncontrolling interest	8	6,675
Increase (decrease) in fair value of derivatives applied to accumulated other comprehensive loss and noncontrolling interests	1,408	(10,414)
Dividends/distributions payable	31,131	30,217
Decrease in noncontrolling interests and increase in shareholders’ equity in connection with the conversion of common units into common shares	2,537	0
Adjustments to noncontrolling interests resulting from changes in COPLP ownership	246	(54)
Increase in redeemable noncontrolling interest and decrease in equity to carry redeemable noncontrolling interest at fair value	545	302
Corporate Office Properties, L.P.
Cash flows from operating activities
Revenues from real estate operations received	133,895	130,474
Construction contract and other service revenues received	23,527	7,747
Property operating expenses paid	(41,192)	(46,084)
Construction contract and other service expenses paid	(14,790)	(10,765)
General, administrative, leasing, business development and land carry costs paid	(14,275)	(12,175)
Interest expense paid	(19,549)	(21,386)
Lease incentives	(7,729)	(415)
Other	750	43
Net cash provided by operating activities	60,637	47,439
Cash flows from investing activities
Construction, development and redevelopment	(35,795)	(45,146)
Tenant improvements on operating properties	(6,916)	(6,388)
Other capital improvements on operating properties	(5,203)	(9,505)
Proceeds from dispositions of properties	52,596	5,452
Leasing costs paid	(2,042)	(1,593)
Other	(717)	1,121
Net cash provided by (used in) investing activities	1,923	(56,059)
Proceeds from debt
Revolving Credit Facility	0	88,500
Repayments of debt
Revolving Credit Facility	0	(25,000)
Scheduled principal amortization	(958)	(1,800)
Other debt repayments	(50)	(50)
Net proceeds from issuance of common shares/units	18,237	(5)
Redemption of preferred shares/units	(26,583)	0
Common share/unit dividends/distributions paid	(28,091)	(27,008)
Preferred share/unit dividends/distributions paid	(3,746)	(3,717)
Redemption of vested equity awards	(1,753)	(1,154)
Distributions paid to redeemable noncontrolling interests	(407)	(13,848)
Other	(2,602)	(5,119)
Net cash (used in) provided by financing activities	(45,953)	10,799
Net increase in cash and cash equivalents	16,607	2,179
Cash and cash equivalents
Beginning of period	209,863	60,310
End of period	226,470	62,489
Reconciliation of net income to net cash provided by operating activities:
Net income	23,088	8,096
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	33,570	35,129
Impairment losses	0	2,446
(Gain) loss on interest rate derivatives	(454)	1,551
Amortization of deferred financing costs and net debt discounts	1,348	1,495
Increase in deferred rent receivable	(191)	(1,456)
Gain on sales of real estate	(4,238)	0
Share-based compensation	1,488	2,108
Other	(1,341)	(802)
Operating changes in assets and liabilities:
Decrease in accounts receivable	5,007	409
Decrease in restricted cash and marketable securities	757	(77)
Decrease in prepaid expenses and other assets, net	13,991	5,941
Decrease in accounts payable, accrued expenses and other liabilities	(10,983)	(3,710)
Decrease in rents received in advance and security deposits	(1,405)	(3,691)
Net cash provided by operating activities	60,637	47,439
Supplemental schedule of non-cash investing and financing activities:
Decrease in accrued capital improvements, leasing and other investing activity costs	(6,661)	(9,420)
Increase in property and redeemable noncontrolling interests in connection with property contributed in a joint venture	0	22,600
Decrease in redeemable noncontrolling interests and increase in other liabilities in connection with distribution payable to redeemable noncontrolling interest	8	6,675
Increase (decrease) in fair value of derivatives applied to accumulated other comprehensive loss and noncontrolling interests	1,408	(10,414)
Dividends/distributions payable	31,131	30,217
Increase in redeemable noncontrolling interest and decrease in equity to carry redeemable noncontrolling interest at fair value	$ 545	$ 302

Organization

Organization	3 Months Ended
	Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	Organization Corporate Office Properties Trust (“COPT”) and subsidiaries (collectively, the “Company”) is a fully-integrated and self-managed real estate investment trust (“REIT”). Corporate Office Properties, L.P. (“COPLP”) and subsidiaries (collectively, the “Operating Partnership”) is the entity through which COPT, the sole general partner of COPLP, conducts almost all of its operations and owns almost all of its assets. Unless otherwise expressly stated or the context otherwise requires, “we”, “us” and “our” as used herein refer to each of the Company and the Operating Partnership. We own, manage, lease, develop and selectively acquire office and data center properties. The majority of our portfolio is in locations that support the United States Government and its contractors, most of whom are engaged in national security, defense and information technology (“IT”) related activities servicing what we believe are growing, durable priority missions (“Defense/IT Locations”). We also own a portfolio of office properties located in select urban/urban-like submarkets within our regional footprint with durable Class-A office fundamentals and characteristics, as well as other properties supporting general commercial office tenants (“Regional Office”). As of March 31, 2017 , our properties included the following: • 164 operating office properties totaling 17.1 million square feet, including 13 triple-net leased, single-tenant data center properties. We owned six of these properties through an unconsolidated real estate joint venture; • nine office properties under construction or redevelopment that we estimate will total approximately 1.3 million square feet upon completion, including two partially operational properties and two properties completed but held for future lease to the United States Government; • 987 acres of land we controlled for future development that we believe could be developed into approximately 12.2 million square feet and an additional 194 acres of other land; and • a wholesale data center with a critical load of 19.25 megawatts. COPLP owns real estate both directly and through subsidiary partnerships and limited liability companies (“LLCs”). In addition to owning real estate, COPLP also owns subsidiaries that provide real estate services such as property management and construction and development services primarily for our properties but also for third parties. Some of these services are performed by a taxable REIT subsidiary (“TRS”). Equity interests in COPLP are in the form of common and preferred units. As of March 31, 2017 , COPT owned 96.7% of the outstanding COPLP common units (“common units”) and 95.1% of the outstanding COPLP preferred units (“preferred units”); the remaining common and preferred units in COPLP were owned by third parties. Common units in COPLP not owned by COPT carry certain redemption rights. The number of common units in COPLP owned by COPT is equivalent to the number of outstanding common shares of beneficial interest (“common shares”) of COPT, and the entitlement of all COPLP common units to quarterly distributions and payments in liquidation is substantially the same as those of COPT common shareholders. Similarly, in the case of each series of preferred units in COPLP held by COPT, there is a series of preferred shares of beneficial interest (“preferred shares”) in COPT that is equivalent in number and carries substantially the same terms as such series of COPLP preferred units. COPT’s common shares are publicly traded on the New York Stock Exchange (“NYSE”) under the ticker symbol “OFC”. Because COPLP is managed by COPT, and COPT conducts substantially all of its operations through COPLP, we refer to COPT’s executive officers as COPLP’s executive officers, and although, as a partnership, COPLP does not have a board of trustees, we refer to COPT’s Board of Trustees as COPLP’s Board of Trustees.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The COPT consolidated financial statements include the accounts of COPT, the Operating Partnership, their subsidiaries and other entities in which COPT has a majority voting interest and control. The COPLP consolidated financial statements include the accounts of COPLP, its subsidiaries and other entities in which COPLP has a majority voting interest and control. We also consolidate certain entities when control of such entities can be achieved through means other than voting rights (“variable interest entities” or “VIEs”) if we are deemed to be the primary beneficiary of such entities. We eliminate all intercompany balances and transactions in consolidation. We use the equity method of accounting when we own an interest in an entity and can exert significant influence over but cannot control the entity’s operations. We discontinue equity method accounting if our investment in an entity (and net advances) is reduced to zero unless we have guaranteed obligations of the entity or are otherwise committed to provide further financial support for the entity. We use the cost method of accounting when we own an interest in an entity and cannot exert significant influence over its operations. These interim financial statements should be read together with the consolidated financial statements and notes thereto as of and for the year ended December 31, 2016 included in our 2016 Annual Report on Form 10-K. The unaudited consolidated financial statements include all adjustments that are necessary, in the opinion of management, to fairly state our financial position and results of operations. All adjustments are of a normal recurring nature. The consolidated financial statements have been prepared using the accounting policies described in our 2016 Annual Report on Form 10-K. Reclassification We reclassified certain amounts from prior periods to conform to the current period presentation of our consolidated financial statements with no effect on previously reported net income or equity. Recent Accounting Pronouncements We adopted guidance issued by the Financial Accounting Standards Board (“FASB”) effective January 1, 2017 intended to simplify various aspects related to the accounting and presentation for employee share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities and classification on the consolidated statement of cash flows. In connection with our adoption of this policy, we made an entity-wide accounting policy election to continue to account for potential future award forfeitures by estimating the number of awards that are expected to vest. Our adoption of this guidance did not have a material impact on our consolidated financial statements. We adopted guidance issued by the FASB prospectively effective January 1, 2017 that clarifies the definition of a business used by entities in determining whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The definition of a business affects many areas of accounting including acquisitions, disposals, goodwill and consolidation. Under the new guidance it is expected that the majority of our future operating property acquisitions will be accounted for as asset acquisitions, whereas under the previous guidance our recent acquisitions were accounted for as business combinations; we believe that the primary effect of this change will be that transaction costs associated with future acquisitions will be capitalized rather than expensed as incurred. This guidance had no effect on our consolidated financial statements upon adoption. In May 2014, the FASB issued guidance regarding the recognition of revenue from contracts with customers. Under this guidance, an entity will recognize revenue to depict the transfer of goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This guidance also requires improved disclosures regarding the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. Also in connection with this guidance, in February 2017, the FASB issued additional guidance that clarifies the scope of asset derecognition guidance and accounting for partial sales of nonfinancial assets. While we are still completing our assessment of the impact of the guidance, below is a summary of the anticipated primary effects on our accounting and reporting. • Construction contract revenue: We reviewed our historical construction management arrangements and related contracts. Based on this review, we believe that we will account for these arrangements using the percentage of completion method, which is the method we have used in most cases historically. We do not currently believe that the resulting effect of the change will be material. • Sales of real estate: The new guidance requires recognition of a sale of real estate and resulting gain or loss when control transfers and the buyer has the ability to direct use of, or obtain substantially all of the remaining benefit from, the asset (which generally will occur on the closing date); the factor of continuing involvement is no longer a specific consideration for the timing of recognition. The new guidance eliminates the need to consider adequacy of buyer investment, which was replaced by additional judgments regarding collectability and intent and/or ability to pay. The new guidance also requires an entity to derecognize nonfinancial assets and in substance non financial assets once it transfers control of such assets. When an entity transfers its controlling interest in a nonfinancial asset, but retains a noncontrolling ownership interest, the entity is required to measure any non-controlling interest it receives or retains at fair value and recognize a full gain or loss on the transaction; as a result, sales and partial sales of real estate assets will now be subject to the same derecognition model as all other nonfinancial assets. Since all but one of our sale transactions previously met the criteria for immediate gain recognition under existing guidance, we do not believe that the recognition pattern for these transactions will be changed by the new guidance. Our one sale transaction that did not meet the criteria for immediate full recognition under the previous standard was our contribution of data center properties into a newly-formed joint venture in July 2016, as discussed further in our 2016 Annual Report on Form 10-K. We believe that this transaction, which was accounted for as a partial sale under existing guidance, would meet the criteria for immediate full gain recognition under the new guidance; this would result in an additional $18 million in income being recognizable in 2016 under the new guidance that is currently being amortized into income in subsequent periods under existing guidance. • Real estate revenue associated with executory costs and other non-lease components: Once the new guidance setting forth principles for the recognition, measurement, presentation and disclosure of leases (discussed below) goes into effect, we believe that the new revenue standard may apply to executory costs and other components of revenue due under leases that are deemed to be non-lease components (such as common area maintenance and provision of utilities), even when the revenue for such activities is not separately stipulated in the lease. In that case, then revenue from these items previously recognized on a straight-line basis under current lease guidance would be recognized under the new revenue guidance as the related services are delivered. As a result, while the total revenue recognized over time would not differ under the new guidance, the recognition pattern would be different. We are in the process of evaluating the significance of the difference in the recognition pattern that would result from this change. We are required to adopt this guidance for our annual and interim periods beginning January 1, 2018 using one of two methods: retrospective restatement for each reporting period presented at the time of adoption, or retrospectively with the cumulative effect of initially applying this guidance recognized at the date of initial application. We have not decided which method of adoption we will use. In February 2016, the FASB issued guidance that sets forth principles for the recognition, measurement, presentation and disclosure of leases. This guidance 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 of the leased asset by the lessee. The resulting classification determines whether the lease expense is recognized based on an effective interest method or straight-line basis over the term of the lease. 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 similar to existing guidance for operating leases. The guidance requires lessors of real estate to account for leases using an approach that is substantially equivalent to existing guidance for sales-type leases, direct financing leases and operating leases. While we are still completing our assessment of the impact of this guidance, below is a summary of the anticipated primary effects of this guidance on our accounting and reporting. • Real estate leases in which we are the lessor: ◦ Balance sheet reporting: We believe that we will apply an approach under the new guidance that is similar to the current accounting for operating leases, in which we will continue to recognize the underlying leased asset as property on our balance sheet. ◦ Deferral of compensation-related lease costs: Under the new lease guidance, lessors may only capitalize their incremental direct costs of leasing. As a result, we believe that we will no longer be able to defer the recognition of compensation-related costs in connection with new or extended tenant leases (refer to amounts reported in our 2016 Annual Report on Form 10-K for amounts deferred in 2014, 2015 and 2016). ◦ Lease revenue reporting: As discussed in further detail above in connection with the new revenue guidance, we believe that the new revenue standard may apply to executory costs and other components of revenue deemed to be non-lease components (such as common area maintenance and provision of utilities), even when the revenue for such activities is not separately stipulated in the lease. In that case, we would need to separate the lease components of revenue due under leases from the non-lease components. Under the new guidance, we would continue to recognize the lease components of lease revenue on a straight-line basis over our respective lease terms as we do under prior guidance. However, we would recognize the non-lease components under the new revenue guidance as the related services are delivered. As discussed above, we are in the process of evaluating the significance of the difference in the recognition pattern that would result from this change. • Leases in which we are the lessee: ◦ Our most significant leases as lessee are ground leases we have for certain properties; as of March 31, 2017 , our future minimum rental payments under these leases totaled $90.7 million , with various expiration dates extending to the year 2100. While we are still in the process of evaluating these leases under the new guidance, we believe that we will be required to recognize a right-of-use asset and a lease liability for the present value of these minimum lease payments. We believe that these leases most likely will be classified as finance leases under the new guidance; as a result, the interest component of each lease payment would be recorded as interest expense and the right-of-use asset would be amortized into expense using the straight-line method over the life of the lease. This guidance is effective for reporting periods beginning January 1, 2019, with modified retrospective restatement for each reporting period presented at the time of adoption. Early adoption is also permitted for this guidance. In June 2016, the FASB issued guidance that changes how entities measure credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. The guidance replaces the current incurred loss model with an expected loss approach, resulting in a more timely recognition of such losses. The guidance will apply to most financial assets measured at amortized cost and certain other instruments, including trade and other receivables, loans, held-to-maturity debt securities, net investments in leases, and off-balance-sheet credit exposures (e.g. loan commitments). Under the new guidance, an entity will recognize its estimate of expected credit losses as an allowance, as the guidance requires that financial assets be measured on an amortized cost basis and to be presented at the net amount expected to be collected. The guidance is effective for us beginning January 1, 2020, with early adoption permitted after December 2018. We are currently assessing the financial impact of this guidance on our consolidated financial statements. In August 2016, the FASB issued guidance that clarifies how entities should classify certain cash receipts and cash payments on the statement of cash flows with the objective of reducing the existing diversity in practice related to eight specific cash flow issues. The areas addressed in the new guidance relate to debt prepayment costs, settlement of zero-coupon debt instruments, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of corporate-owned and bank-owned life insurance policies, distributions received from equity method investments, beneficial interest in securitization transactions and separately identifiable cash flows and application of the predominance principle. The guidance is effective for us beginning January 1, 2018, with early adoption permitted. We do not expect the adoption of this guidance to have a material impact on our consolidated financial statements. In November 2016, the FASB issued guidance that requires the statement of cash flows to explain the change during the period in the total of cash, cash equivalents and amounts described as restricted cash or restricted cash equivalents. Under the new guidance, amounts described as restricted cash and restricted cash equivalents will be included with cash and cash equivalents when reconciling the beginning of period and end of period total amounts shown on the statement of cash flows. The guidance is effective for us beginning January 1, 2018, with early adoption permitted. We do not expect the adoption of this guidance to have a material impact on our consolidated financial statements.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Recurring Fair Value Measurements COPT has a non-qualified elective deferred compensation plan for Trustees and certain members of our management team that permits participants to defer up to 100% of their compensation on a pre-tax basis and receive a tax-deferred return on such deferrals. The assets held in the plan (comprised primarily of mutual funds and equity securities) and the corresponding liability to the participants are measured at fair value on a recurring basis on COPT’s consolidated balance sheet using quoted market prices, as are other marketable securities that we hold. The balance of the plan, which was fully funded, totaled $4.2 million as of March 31, 2017 , and is included in the accompanying COPT consolidated balance sheets in the line entitled restricted cash and marketable securities. The offsetting liability associated with the plan is adjusted to fair value at the end of each accounting period based on the fair value of the plan assets and reported in other liabilities on COPT’s consolidated balance sheets. The assets of the plan and other marketable securities that we hold are classified in Level 1 of the fair value hierarchy. The liability associated with the plan is classified in Level 2 of the fair value hierarchy. The fair values of our interest rate derivatives are determined using widely accepted valuation techniques, including a discounted cash flow analysis on the expected cash flows of each derivative. This analysis reflects the contractual terms of the derivatives, including the period to maturity, and uses observable market-based inputs, including interest rate market data and implied volatilities in such interest rates. While we determined that the majority of the inputs used to value our derivatives fall within Level 2 of the fair value hierarchy, the credit valuation adjustments associated with our interest rate derivatives utilize Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default. However, as of March 31, 2017 , we assessed the significance of the impact of the credit valuation adjustments on the overall valuation of our derivatives and determined that these adjustments are not significant. As a result, we determined that our interest rate derivative valuations in their entirety are classified in Level 2 of the fair value hierarchy. The carrying values of cash and cash equivalents, restricted cash, accounts receivable, other assets (excluding investing receivables) and accounts payable and accrued expenses are reasonable estimates of their fair values because of the short maturities of these instruments. As discussed in Note 6, we estimated the fair values of our investing receivables based on the discounted estimated future cash flows of the loans (categorized within Level 3 of the fair value hierarchy); the discount rates used approximate current market rates for loans with similar maturities and credit quality, and the estimated cash payments include scheduled principal and interest payments. For our disclosure of debt fair values in Note 8, we estimated the fair value of our unsecured senior notes based on quoted market rates for publicly-traded debt (categorized within Level 2 of the fair value hierarchy) and estimated the fair value of our other debt based on the discounted estimated future cash payments to be made on such debt (categorized within Level 3 of the fair value hierarchy); the discount rates used approximate current market rates for loans, or groups of loans, with similar maturities and credit quality, and the estimated future payments include scheduled principal and interest payments. Fair value estimates are made as of a specific point in time, are subjective in nature and involve uncertainties and matters of significant judgment. Settlement at such fair value amounts may not be possible and may not be a prudent management decision. For additional fair value information, please refer to Note 6 for investing receivables, Note 8 for debt and Note 9 for interest rate derivatives. COPT and Subsidiaries The table below sets forth financial assets and liabilities of COPT and its subsidiaries that are accounted for at fair value on a recurring basis as of March 31, 2017 and the hierarchy level of inputs used in measuring their respective fair values under applicable accounting standards (in thousands): Description Quoted Prices in Significant Other Significant Total Assets: Marketable securities in deferred compensation plan (1) Mutual funds $ 4,075 $ — $ — $ 4,075 Other 76 — — 76 Interest rate derivatives (2) — 1,183 — 1,183 Total assets $ 4,151 $ 1,183 $ — $ 5,334 Liabilities: Deferred compensation plan liability (3) $ — $ 4,151 $ — $ 4,151 Interest rate derivatives (3) — 735 — 735 Total liabilities $ — $ 4,886 $ — $ 4,886 (1) Included in the line entitled “restricted cash and marketable securities” on COPT’s consolidated balance sheet. (2) Included in the line entitled “prepaid expenses and other assets” on COPT ’ s consolidated balance sheet. (3) Included in the line entitled “other liabilities” on COPT’s consolidated balance sheet. COPLP and Subsidiaries The table below sets forth financial assets and liabilities of COPLP and its subsidiaries that are accounted for at fair value on a recurring basis as of March 31, 2017 and the hierarchy level of inputs used in measuring their respective fair values under applicable accounting standards (in thousands): Description Quoted Prices in Significant Other Significant Total Assets: Interest rate derivatives (1) $ — $ 1,183 $ — $ 1,183 Liabilities: Interest rate derivatives (2) $ — $ 735 $ — $ 735 (1) Included in the line entitled “prepaid expenses and other assets” on COPLP ’ s consolidated balance sheet. (2) Included in the line entitled “other liabilities” on COPLP ’ s consolidated balance sheet. Nonrecurring Fair Value Measurements As part of our closing process for the first quarter of 2017, we conducted our quarterly review of our portfolio for indicators of impairment and found there to be no impairment losses for the quarter. Changes in the expected future cash flows due to changes in our plans for specific properties (especially our expected holding period) could result in the recognition of impairment losses. In addition, because properties held for sale are carried at the lower of carrying value or estimated fair values less costs to sell, declines in their estimated fair values due to market conditions and other factors could result in the recognition of impairment losses. The table below sets forth the fair value hierarchy of the valuation technique we used to determine nonrecurring fair value measurements of properties held for sale as of March 31, 2017 (dollars in thousands): Fair Values as of March 31, 2017 Quoted Prices in Significant Active Markets for Significant Other Unobservable Identical Assets Observable Inputs Inputs Description (Level 1) (Level 2) (Level 3) Total Assets: Assets held for sale, net $ — $ — $ 40,086 $ 40,086 The table below sets forth quantitative information about significant unobservable inputs used for the Level 3 fair value measurements reported above as of March 31, 2017 (dollars in thousands): Valuation Technique Fair Values on Measurement Date Unobservable Input Range (Weighted Average) Discounted cash flow $ 37,604 Discount rate 9.3% - 11.3% (10.1%) Terminal capitalization rate 8.3% - 11.4% (8.6%) Yield analyses $ 2,482 Investor yield requirement 9.0% (1) (1) Only one fair value applied for this unobservable input.

Properties, Net

Properties, Net	3 Months Ended
	Mar. 31, 2017
Real Estate [Abstract]
Properties, Net	Properties, Net Operating properties, net consisted of the following (in thousands): March 31, December 31, Land $ 430,364 $ 433,311 Buildings and improvements 2,972,164 2,944,905 Less: Accumulated depreciation (732,371 ) (706,385 ) Operating properties, net $ 2,670,157 $ 2,671,831 Projects in development or held for future development consisted of the following (in thousands): March 31, December 31, Land $ 195,727 $ 195,521 Development in progress, excluding land 227,130 206,010 Projects in development or held for future development $ 422,857 $ 401,531 Our properties held for sale included: • as of March 31, 2017 : six operating properties in White Marsh, Maryland (included in our Regional Office segment); one operating property in our Fort Meade/BW Corridor sub-segment; and land in White Marsh; and • as of December 31, 2016 : eight operating properties in White Marsh (included primarily in our Regional Office segment); one operating property in our Northern Virginia Defense/IT sub-segment; and land in White Marsh and Northern Virginia. The table below sets forth the components of assets held for sale on our consolidated balance sheet for these properties (in thousands): March 31, 2017 December 31, 2016 Properties, net $ 38,018 $ 85,402 Deferred rent receivable 1,546 4,241 Intangible assets on real estate acquisitions, net 338 338 Deferred leasing costs, net 1,109 3,636 Lease incentives, net 380 1,037 Assets held for sale, net $ 41,391 $ 94,654 2017 Dispositions On February 15, 2017, we completed the disposition of 3120 Fairview Park Drive, an operating property totaling 190,000 square feet in Falls Church, Virginia (in our Northern Virginia Defense/IT sub-segment), for $39.0 million , with no gain recognized. We also sold land in the three months ended March 31, 2017 for $14.3 million and recognized a gain on sale of $4.2 million . 2017 Construction Activities During the three months ended March 31, 2017 , we placed into service 86,000 square feet in three redeveloped properties (including a partially operational property). As of March 31, 2017 , we had eight office properties under construction, or for which we were contractually committed to construct, that we estimate will total 1.3 million square feet upon completion (including two properties completed but held for future lease to the United States Government) and one office property under redevelopment that we estimate will total 14,000 square feet upon completion.

Real Estate Joint Ventures

Real Estate Joint Ventures	3 Months Ended
	Mar. 31, 2017
Equity Method Investments and Joint Ventures [Abstract]
Real Estate Joint Ventures	Real Estate Joint Ventures Consolidated Joint Ventures The table below sets forth information pertaining to our investments in consolidated real estate joint ventures as of March 31, 2017 (dollars in thousands): Nominal Ownership March 31, 2017 (1) Date % as of Total Encumbered Total Acquired 3/31/2017 Nature of Activity Assets Assets Liabilities LW Redstone Company, LLC 3/23/2010 85% Development and operation of real estate (2) $ 157,293 $ 78,251 $ 50,804 M Square Associates, LLC 6/26/2007 50% Development and operation of real estate (3) 65,158 46,124 45,712 Stevens Investors, LLC 8/11/2015 95% Development of real estate (4) 42,176 — 7,252 $ 264,627 $ 124,375 $ 103,768 (1) Excludes amounts eliminated in consolidation. (2) This joint venture’s properties are in Huntsville, Alabama. (3) This joint venture’s properties are in College Park, Maryland. (4) This joint venture’s property is in Washington, DC. Our partner in this joint venture is entitled to receive an additional distribution from the joint venture of $6.7 million to be funded by us (expected by 2018) that was reported in other liabilities on our consolidated balance sheet as of March 31, 2017 . Unconsolidated Joint Venture As of March 31, 2017, we owned a 50% interest in GI-COPT DC Partnership LLC (“GI-COPT”), a joint venture owning six triple-net leased, single-tenant data center properties in Virginia, that we account for using the equity method of accounting. As of March 31, 2017 , we had an investment balance in GI-COPT of $25.4 million . Our balance was $17.8 million lower than our share of the joint venture’s equity due to a difference between our cost basis and our share of the underlying equity in the net assets upon formation of the joint venture; we are amortizing this basis difference into equity in income from unconsolidated entities over the lives of the underlying assets.

Investing Receivables

Investing Receivables	3 Months Ended
	Mar. 31, 2017
Receivables [Abstract]
Investing Receivables	Investing Receivables Investing receivables, including accrued interest thereon, consisted of the following (in thousands): March 31, December 31, Notes receivable from the City of Huntsville $ 50,570 $ 49,258 Other investing loans receivable 3,000 3,021 $ 53,570 $ 52,279 Our notes receivable from the City of Huntsville funded infrastructure costs in connection with our LW Redstone Company, LLC joint venture (see Note 5) and carry an interest rate of 9.95% . We did not have an allowance for credit losses in connection with our investing receivables as of March 31, 2017 or December 31, 2016 . The fair value of these receivables approximated their carrying amounts as of March 31, 2017 and December 31, 2016 .

Prepaid Expenses and Other Asse

Prepaid Expenses and Other Assets, Net	3 Months Ended
	Mar. 31, 2017
Prepaid Expense and Other Assets [Abstract]
Prepaid Expenses and Other Assets, Net	Prepaid Expenses and Other Assets, Net Prepaid expenses and other assets, net consisted of the following (in thousands): March 31, December 31, Lease incentives, net $ 17,516 $ 18,276 Prepaid expenses 17,332 24,432 Furniture, fixtures and equipment, net 4,989 5,204 Construction contract costs incurred in excess of billings 4,451 10,350 Deferred tax asset, net (1) 2,980 3,036 Deferred financing costs, net (2) 2,444 3,128 Non-real estate equity method investments 2,353 2,355 Other assets 7,658 5,983 Prepaid expenses and other assets, net $ 59,723 $ 72,764 (1) Includes a valuation allowance of $2.1 million . (2) Represents deferred costs, net of accumulated amortization, attributable to our Revolving Credit Facility and interest rate derivatives.

Debt, Net

Debt, Net	3 Months Ended
	Mar. 31, 2017
Debt Disclosure [Abstract]
Debt, Net	Debt, Net Our debt consisted of the following (dollars in thousands): Carrying Value (1) as of March 31, December 31, Stated Interest Rates as of Scheduled Maturity as of March 31, 2017 March 31, 2017 Mortgage and Other Secured Debt: Fixed rate mortgage debt (2) $ 153,294 $ 154,143 3.82% - 7.87% (3) 2019-2026 Variable rate secured debt 13,365 13,448 LIBOR + 1.85% (4) October 2020 Total mortgage and other secured debt 166,659 167,591 Revolving Credit Facility — — LIBOR + 0.875% to 1.60% May 2019 Term Loan Facilities (5) 547,682 547,494 LIBOR + 0.90% to 2.40% (6) 2020-2022 Unsecured Senior Notes 3.600%, $350,000 aggregate principal 347,233 347,128 3.60% (7) May 2023 5.250%, $250,000 aggregate principal 246,291 246,176 5.25% (8) February 2024 3.700%, $300,000 aggregate principal 297,961 297,843 3.70% (9) June 2021 5.000%, $300,000 aggregate principal 296,457 296,368 5.00% (10) July 2025 Unsecured notes payable 1,374 1,401 0% (11) 2026 Total debt, net $ 1,903,657 $ 1,904,001 (1) The carrying values of our debt other than the Revolving Credit Facility reflect net deferred financing costs of $5.7 million as of March 31, 2017 and $6.1 million as of December 31, 2016 . (2) Certain fixed rate mortgages carry interest rates that were above or below market rates upon assumption and therefore were recorded at their fair value based on applicable effective interest rates. The carrying values of these loans reflect net unamortized premiums totaling $403,000 as of March 31, 2017 and $422,000 as of December 31, 2016 . (3) The weighted average interest rate on our fixed rate mortgage debt was 4.19% as of March 31, 2017 . (4) The interest rate on our variable rate secured debt as of March 31, 2017 was 2.63% . (5) As of March 31, 2017 , we have the ability to borrow an additional $350.0 million in the aggregate under these term loan facilities, provided that there is no default under the facilities and subject to the approval of the lenders. (6) The weighted average interest rate on these loans was 2.37% as of March 31, 2017 . (7) The carrying value of these notes reflects an unamortized discount totaling $1.9 million as of March 31, 2017 and $2.0 million as of December 31, 2016 . The effective interest rate under the notes, including amortization of the issuance costs, was 3.70% . (8) The carrying value of these notes reflects an unamortized discount totaling $3.3 million as of March 31, 2017 and $3.4 million as of December 31, 2016 . The effective interest rate under the notes, including amortization of the issuance costs, was 5.49% . (9) The carrying value of these notes reflects an unamortized discount totaling $1.6 million as of March 31, 2017 and $1.7 million as of December 31, 2016 . The effective interest rate under the notes, including amortization of the issuance costs, was 3.85% . (10) The carrying value of these notes reflects an unamortized discount totaling $2.9 million as of March 31, 2017 and $3.0 million as of December 31, 2016 . The effective interest rate under the notes, including amortization of the issuance costs, was 5.15% . (11) These notes carry interest rates that were below market rates upon assumption and therefore were recorded at their fair value based on applicable effective interest rates. The carrying value of these notes reflects an unamortized discount totaling $438,000 as of March 31, 2017 and $460,000 as of December 31, 2016 . All debt is owed by the Operating Partnership. While COPT is not directly obligated by any debt, it has guaranteed the Operating Partnership’s Revolving Credit Facility, Term Loan Facilities and Unsecured Senior Notes. Certain of our debt instruments require that we comply with a number of restrictive financial covenants. As of March 31, 2017 , we were within the compliance requirements of these financial covenants. We capitalized interest costs of $1.5 million in the three months ended March 31, 2017 and $1.8 million in the three months ended March 31, 2016 . The following table sets forth information pertaining to the fair value of our debt (in thousands): March 31, 2017 December 31, 2016 Carrying Estimated Carrying Estimated Amount Fair Value Amount Fair Value Fixed-rate debt Unsecured Senior Notes $ 1,187,942 $ 1,223,753 $ 1,187,515 $ 1,220,282 Other fixed-rate debt 154,668 156,098 155,544 156,887 Variable-rate debt 561,047 556,844 560,942 558,437 $ 1,903,657 $ 1,936,695 $ 1,904,001 $ 1,935,606

Interest Rate Derivatives

Interest Rate Derivatives	3 Months Ended
	Mar. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Interest Rate Derivatives	Interest Rate Derivatives The following table sets forth the key terms and fair values of our interest rate swap derivatives (dollars in thousands): Fair Value at Notional Amount Fixed Rate Floating Rate Index Effective Date Expiration Date March 31, December 31, $ 100,000 1.6730% One-Month LIBOR 9/1/2015 8/1/2019 $ (301 ) $ (701 ) 100,000 1.7300% One-Month LIBOR 9/1/2015 8/1/2019 (434 ) (848 ) 13,494 (1) 1.3900% One-Month LIBOR 10/13/2015 10/1/2020 147 100 100,000 1.9013% One-Month LIBOR 9/1/2016 12/1/2022 409 (23 ) 100,000 1.9050% One-Month LIBOR 9/1/2016 12/1/2022 427 48 50,000 1.9079% One-Month LIBOR 9/1/2016 12/1/2022 200 10 $ 448 $ (1,414 ) (1) The notional amount of this instrument is scheduled to amortize to $12.1 million . Each of the interest rate swaps set forth in the table above was designated as a cash flow hedge of interest rate risk. The table below sets forth the fair value of our interest rate derivatives as well as their classification on our consolidated balance sheets (in thousands): Fair Value at Derivatives Balance Sheet Location March 31, December 31, 2016 Interest rate swaps designated as cash flow hedges Prepaid expenses and other assets $ 1,183 $ 158 Interest rate swaps designated as cash flow hedges Other liabilities (735 ) (1,572 ) The table below presents the effect of our interest rate derivatives on our consolidated statements of operations and comprehensive income (in thousands): For the Three Months Ended March 31, 2017 2016 Amount of gain (loss) recognized in accumulated other comprehensive loss (“AOCL”) (effective portion) $ 224 $ (11,284 ) Amount of losses reclassified from AOCL into interest expense (effective portion) (1,184 ) (870 ) Amount of gain (loss) recognized in interest expense (ineffective portion) 454 (1,551 ) Over the next 12 months, we estimate that approximately $2.6 million of losses will be reclassified from AOCL as an increase to interest expense. We have agreements with each of our interest rate derivative counterparties that contain provisions under which, if we default or are capable of being declared in default on defined levels of our indebtedness, we could also be declared in default on our derivative obligations. Failure to comply with the loan covenant provisions could result in our being declared in default on any derivative instrument obligations covered by the agreements. As of March 31, 2017 , the fair value of interest rate derivatives in a liability position related to these agreements was $735,000 , excluding the effects of accrued interest and credit valuation adjustments. As of March 31, 2017 , we had not posted any collateral related to these agreements. We are not in default with any of these provisions. If we breached any of these provisions, we could be required to settle our obligations under the agreements at their termination value of $892,000 .

Redeemable Noncontrolling Inter

Redeemable Noncontrolling Interests	3 Months Ended
	Mar. 31, 2017
Noncontrolling Interest [Abstract]
Redeemable Noncontrolling Interests	Redeemable Noncontrolling Interests Our partners in two real estate joint ventures, LW Redstone Company, LLC and Stevens Investors, LLC (discussed further in Note 5), have the right to require us to acquire their respective interests at fair value; accordingly, we classify the fair value of our partners’ interests as redeemable noncontrolling interests in the mezzanine section of our consolidated balance sheet. We determine the fair value of the interests based on unobservable inputs after considering the assumptions that market participants would make in pricing the interest. We apply a discount rate to the estimated future cash flows allocable to our partners from the properties underlying the respective joint ventures. Estimated cash flows used in such analyses are based on our plans for the properties and our views of market and economic conditions, and consider items such as current and future rental rates, occupancies for the properties and comparable properties and estimated operating and capital expenditures. The table below sets forth the activity for these redeemable noncontrolling interests (in thousands): For the Three Months Ended March 31, 2017 2016 Beginning balance $ 22,979 $ 19,218 Contributions from noncontrolling interests — 22,779 Distributions to noncontrolling interests (415 ) (20,526 ) Net income attributable to noncontrolling interests 567 560 Adjustment to arrive at fair value of interests 545 302 Ending balance $ 23,676 $ 22,333

Equity

Equity	3 Months Ended
	Mar. 31, 2017
Equity [Abstract]
Equity	Equity COPT redeemed all of the outstanding shares of its Series K Cumulative Redeemable Preferred Shares (the “Series K Preferred Shares”) effective January 21, 2017 at a price of $50.00 per share, or $26.6 million in the aggregate, plus accrued and unpaid dividends thereon through the date of redemption. Concurrently with this redemption, COPLP redeemed its Series K Preferred Units on the same terms. Since we made an irrevocable notification to holders of the Series K Preferred Shares in December 2016 of our intention to redeem such shares, we presented the liquidation preference of the shares/units as a liability on the consolidated balance sheets of COPT and COPLP as of December 31, 2016; we also recognized a $17,000 decrease to net income available to common shareholders/unitholders in the three months ended December 31, 2016 pertaining to the original issuance costs incurred on the shares/units. During the three months ended March 31, 2017 , COPT issued 546,782 common shares at a weighted average price of $33.89 per share under its existing at-the-market (“ATM”) stock offering program. Net proceeds from the shares issued totaled $18.3 million , after payment of $278,000 in commissions to sales agents. COPT contributed the net proceeds from these issuances to COPLP in exchange for an equal number of units in COPLP. COPT’s remaining capacity under this ATM program is an aggregate gross sales price of $71.5 million in common share sales. During the three months ended March 31, 2017 , certain COPLP limited partners converted 185,000 common units in COPLP for an equal number of common shares in COPT. See Note 13 for disclosure of COPT common share and COPLP common unit activity pertaining to our share-based compensation plans.

Information by Business Segment

Information by Business Segment	3 Months Ended
	Mar. 31, 2017
Segment Reporting [Abstract]
Information by Business Segment	Information by Business Segment We have the following reportable segments: Defense/IT Locations; Regional Office; our operating wholesale data center; and other. We also report on Defense/IT Locations sub-segments, which include the following: Fort George G. Meade and the Baltimore/Washington Corridor (referred to herein as “Fort Meade/BW Corridor”); Northern Virginia Defense/IT Locations; Lackland Air Force Base (in San Antonio); locations serving the U.S. Navy (“Navy Support Locations”), which included properties proximate to the Washington Navy Yard, the Naval Air Station Patuxent River in Maryland and the Naval Surface Warfare Center Dahlgren Division in Virginia; Redstone Arsenal (in Huntsville); and data center shells (properties leased to tenants to be operated as data centers in which the tenants generally fund the costs for the power, fiber connectivity and data center infrastructure). We measure the performance of our segments through the measure we define as net operating income from real estate operations (“NOI from real estate operations”), which includes: real estate revenues and property operating expenses; and the net of revenues and property operating expenses of real estate operations owned through unconsolidated real estate joint ventures (“UJVs”) that is allocable to COPT’s ownership interest (“UJV NOI allocable to COPT”). Amounts reported for segment assets represent long-lived assets associated with consolidated operating properties (including the carrying value of properties, intangible assets, deferred leasing costs, deferred rents receivable and lease incentives) and the carrying value of investments in UJVs owning operating properties. Amounts reported as additions to long-lived assets represent additions to existing consolidated operating properties, excluding transfers from non-operating properties, which we report separately. The table below reports segment financial information for our reportable segments (in thousands): Operating Office Property Segments Defense/Information Technology Locations Fort Meade/BW Corridor Northern Virginia Defense/IT Lackland Air Force Base Navy Support Locations Redstone Arsenal Data Center Shells Total Defense/IT Locations Regional Office Operating Other Total Three Months Ended March 31, 2017 Revenues from real estate operations $ 60,855 $ 11,707 $ 11,634 $ 7,010 $ 3,460 $ 5,522 $ 100,188 $ 18,276 $ 6,770 $ 1,533 $ 126,767 Property operating expenses (20,520 ) (4,452 ) (6,802 ) (3,209 ) (1,371 ) (659 ) (37,013 ) (7,486 ) (3,365 ) (655 ) (48,519 ) UJV NOI allocable to COPT — — — — — 1,298 1,298 — — — 1,298 NOI from real estate operations $ 40,335 $ 7,255 $ 4,832 $ 3,801 $ 2,089 $ 6,161 $ 64,473 $ 10,790 $ 3,405 $ 878 $ 79,546 Additions to long-lived assets $ 3,422 $ 2,468 $ — $ 2,168 $ 132 $ — $ 8,190 $ 7,120 $ 1,574 $ 156 $ 17,040 Transfers from non-operating properties $ 13,416 $ 222 $ — $ — $ (4 ) $ (1,015 ) $ 12,619 $ — $ 8 $ 18 $ 12,645 Segment assets at March 31, 2017 $ 1,258,437 $ 361,449 $ 131,194 $ 195,892 $ 109,171 $ 206,489 $ 2,262,632 $ 439,079 $ 229,630 $ 21,011 $ 2,952,352 Three Months Ended March 31, 2016 Revenues from real estate operations $ 62,509 $ 12,116 $ 10,225 $ 6,934 $ 3,116 $ 6,330 $ 101,230 $ 23,502 $ 6,493 $ 1,862 $ 133,087 Property operating expenses (23,246 ) (4,541 ) (5,420 ) (3,524 ) (978 ) (810 ) (38,519 ) (9,831 ) (2,661 ) (864 ) (51,875 ) NOI from real estate operations $ 39,263 $ 7,575 $ 4,805 $ 3,410 $ 2,138 $ 5,520 $ 62,711 $ 13,671 $ 3,832 $ 998 $ 81,212 Additions to long-lived assets $ 6,519 $ 3,078 $ — $ 1,270 $ 618 $ — $ 11,485 $ 2,759 $ — $ 157 $ 14,401 Transfers from non-operating properties $ 35,751 $ (94 ) $ 6 $ — $ 211 $ 26,097 $ 61,971 $ 82 $ 51 $ (11 ) $ 62,093 Segment assets at March 31, 2016 $ 1,319,444 $ 407,199 $ 133,757 $ 195,306 $ 107,693 $ 227,808 $ 2,391,207 $ 603,662 $ 240,484 $ 70,039 $ 3,305,392 The following table reconciles our segment revenues to total revenues as reported on our consolidated statements of operations (in thousands): For the Three Months Ended March 31, 2017 2016 Segment revenues from real estate operations $ 126,767 $ 133,087 Construction contract and other service revenues 13,034 11,220 Total revenues $ 139,801 $ 144,307 The following table reconciles UJV NOI allocable to COPT to equity in income of unconsolidated entities as reported on our consolidated statements of operations (in thousands): For the Three Months Ended March 31, 2017 2016 UJV NOI allocable to COPT $ 1,298 $ — Less: Income from UJV allocable to COPT attributable to depreciation and amortization expense and interest expense (572 ) — Add: Equity in (loss) income of unconsolidated non-real estate entities (1 ) 10 Equity in income of unconsolidated entities $ 725 $ 10 As previously discussed, we provide real estate services such as property management and construction and development services primarily for our properties but also for third parties. The primary manner in which we evaluate the operating performance of our service activities is through a measure we define as net operating income from service operations (“NOI from service operations”), which is based on the net of revenues and expenses from these activities. Construction contract and other service revenues and expenses consist primarily of subcontracted costs that are reimbursed to us by the customer along with a management fee. The operating margins from these activities are small relative to the revenue. We believe NOI from service operations is a useful measure in assessing both our level of activity and our profitability in conducting such operations. The table below sets forth the computation of our NOI from service operations (in thousands): For the Three Months Ended March 31, 2017 2016 Construction contract and other service revenues $ 13,034 $ 11,220 Construction contract and other service expenses (12,486 ) (10,694 ) NOI from service operations $ 548 $ 526 The following table reconciles our NOI from real estate operations for reportable segments and NOI from service operations to income from before gain on sales of real estate as reported on our consolidated statements of operations (in thousands): For the Three Months Ended March 31, 2017 2016 NOI from real estate operations $ 79,546 $ 81,212 NOI from service operations 548 526 Interest and other income 1,726 1,156 Equity in income of unconsolidated entities 725 10 Income tax (expense) benefit (40 ) 8 Depreciation and other amortization associated with real estate operations (33,059 ) (34,527 ) Impairment losses — (2,446 ) General, administrative and leasing expenses (8,611 ) (11,883 ) Business development expenses and land carry costs (1,693 ) (2,418 ) Interest expense (18,994 ) (23,559 ) Less: UJV NOI allocable to COPT included in equity in income of unconsolidated entities (1,298 ) — Gain on early extinguishment of debt — 17 Income before gain on sales of real estate $ 18,850 $ 8,096 The following table reconciles our segment assets to the consolidated total assets of COPT and subsidiaries (in thousands): March 31, March 31, Segment assets $ 2,952,352 $ 3,305,392 Non-operating property assets 429,690 444,334 Other assets 357,324 188,182 Total COPT consolidated assets $ 3,739,366 $ 3,937,908 The accounting policies of the segments are the same as those used to prepare our consolidated financial statements, except that discontinued operations and UJV NOI allocable to COPT are not presented separately for segment purposes. In the segment reporting presented above, we did not allocate interest expense, depreciation and amortization, impairment losses, gain on early extinguishment of debt, gain on sales of real estate and equity in (loss) income of unconsolidated entities not included in NOI to our real estate segments since they are not included in the measure of segment profit reviewed by management. We also did not allocate general, administrative and leasing expenses, business development expenses and land carry costs, interest and other income, income taxes and noncontrolling interests because these items represent general corporate or non-operating property items not attributable to segments.

Share-Based Compensation and Ot

Share-Based Compensation and Other Compensation Matters	3 Months Ended
	Mar. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Compensation and Other Compensation Matters	Share-Based Compensation and Other Compensation Matters Performance Share Units (“PSUs”) On January 1, 2017 , our Board of Trustees granted 36,525 PSUs with an aggregate grant date fair value of $1.4 million to executives. The PSUs have a performance period beginning on January 1, 2017 and concluding on the earlier of December 31, 2019 or the date of: (1) termination by us without cause, death or disability of the executive or constructive discharge of the executive (collectively, “qualified termination”); or (2) a sale event. The number of PSUs earned (“earned PSUs”) at the end of the performance period will be determined based on the percentile rank of COPT’s total shareholder return relative to a peer group of companies, as set forth in the following schedule: Percentile Rank Earned PSUs Payout % 75th or greater 200% of PSUs granted 50th or greater 100% of PSUs granted 25th 50% of PSUs granted Below 25th 0% of PSUs granted If the percentile rank exceeds the 25th percentile and is between two of the percentile ranks set forth in the table above, then the percentage of the earned PSUs will be interpolated between the ranges set forth in the table above to reflect any performance between the listed percentiles. At the end of the performance period, we, in settlement of the award, will issue a number of fully-vested COPT common shares equal to the sum of: • the number of earned PSUs in settlement of the award plan; plus • the aggregate dividends that would have been paid with respect to the common shares issued in settlement of the earned PSUs through the date of settlement had such shares been issued on the grant date, divided by the share price on such settlement date, as defined under the terms of the agreement. If a performance period ends due to a sale event or qualified termination, the number of earned PSUs is prorated based on the portion of the three -year performance period that has elapsed. If employment is terminated by the employee or by us for cause, all PSUs are forfeited. PSUs do not carry voting rights. We computed a grant date fair value of $38.43 per PSU using a Monte Carlo model, which included assumptions of, among other things, the following: baseline common share value of $31.22 ; expected volatility for COPT common shares of 19.0% ; and a risk-free interest rate of 1.47% . We are recognizing the grant date fair value in connection with these PSU awards over the period commencing on January 1, 2017 and ending on December 31, 2019 . We issued 9,763 common shares on February 7, 2017 to Mr. Stephen E. Budorick, our Chief Executive Officer, in settlement of PSUs issued in 2014, representing 100% of the target award for those PSUs. Restricted Shares During the three months ended March 31, 2017 , certain employees were granted a total of 208,953 restricted common shares with an aggregate grant date fair value of $7.1 million (weighted average of $34.02 per share). Restricted shares granted to employees vest based on increments and over periods of time set forth under the terms of the respective awards provided that the employees remain employed by us. During the three months ended March 31, 2017 , forfeiture restrictions lapsed on 139,201 previously issued common shares; these shares had a weighted average grant date fair value of $26.21 per share, and the aggregate intrinsic value of the shares on the vesting dates was $4.7 million .

Earnings Per Share ("EPS") and

Earnings Per Share ("EPS") and Earnings Per Unit ("EPU")	3 Months Ended
	Mar. 31, 2017
Earnings Per Share [Abstract]
Earnings Per Share (“EPS”) and Earnings Per Unit (“EPU”)	Earnings Per Share (“EPS”) and Earnings Per Unit (“EPU”) COPT and Subsidiaries EPS We present both basic and diluted EPS. We compute basic EPS by dividing net income available to common shareholders allocable to unrestricted common shares under the two-class method by the weighted average number of unrestricted common shares outstanding during the period. Our computation of diluted EPS is similar except that: • the denominator is increased to include: (1) the weighted average number of potential additional common shares that would have been outstanding if securities that are convertible into COPT common shares were converted; and (2) the effect of dilutive potential common shares outstanding during the period attributable to share-based compensation using the treasury stock or if-converted methods; and • the numerator is adjusted to add back any changes in income or loss that would result from the assumed conversion into common shares that we added to the denominator. Summaries of the numerator and denominator for purposes of basic and diluted EPS calculations are set forth below (in thousands, except per share data): For the Three Months Ended March 31, 2017 2016 Numerator: Net income attributable to COPT $ 21,355 $ 6,826 Preferred share dividends (3,180 ) (3,552 ) Income attributable to share-based compensation awards (125 ) (118 ) Numerator for basic and diluted EPS on net income attributable to COPT common shareholders $ 18,050 $ 3,156 Denominator (all weighted averages): Denominator for basic EPS (common shares) 98,411 94,203 Dilutive effect of share-based compensation awards 155 95 Denominator for diluted EPS (common shares) 98,566 94,298 Basic EPS: Net income attributable to COPT common shareholders $ 0.18 $ 0.03 Diluted EPS: Net income attributable to COPT common shareholders $ 0.18 $ 0.03 Our diluted EPS computations do not include the effects of the following securities since the conversions of such securities would increase diluted EPS for the respective periods (in thousands): Weighted Average Shares Excluded from Denominator For the Three Months Ended March 31, 2017 2016 Conversion of common units 3,446 3,677 Conversion of Series I Preferred Units 176 176 Conversion of Series K Preferred Shares — 434 The following share-based compensation securities were excluded from the computation of diluted EPS because their effects were antidilutive: • weighted average restricted shares and deferred share awards for the three months ended March 31, 2017 and 2016 of 392,000 and 405,000 , respectively; and • weighted average options for the three months ended March 31, 2017 and 2016 of 140,000 and 379,000 , respectively. COPLP and Subsidiaries EPU We present both basic and diluted EPU. We compute basic EPU by dividing net income available to common unitholders allocable to unrestricted common units under the two-class method by the weighted average number of unrestricted common units outstanding during the period. Our computation of diluted EPU is similar except that: • the denominator is increased to include: (1) the weighted average number of potential additional common units that would have been outstanding if securities that are convertible into our common units were converted; and (2) the effect of dilutive potential common units outstanding during the period attributable to share-based compensation using the treasury stock or if-converted methods; and • the numerator is adjusted to add back any changes in income or loss that would result from the assumed conversion into common units that we added to the denominator. Summaries of the numerator and denominator for purposes of basic and diluted EPU calculations are set forth below (in thousands, except per unit data): For the Three Months Ended March 31, 2017 2016 Numerator: Net income attributable to COPLP common unitholders $ 22,154 $ 7,117 Preferred unit distributions (3,345 ) (3,717 ) Income attributable to share-based compensation awards (125 ) (118 ) Numerator for basic and diluted EPU on net income attributable to COPLP common unitholders $ 18,684 $ 3,282 Denominator (all weighted averages): Denominator for basic EPU (common units) 101,857 97,880 Dilutive effect of share-based compensation awards 155 95 Denominator for diluted EPU (common units) 102,012 97,975 Basic EPU: Net income attributable to COPLP common unitholders $ 0.18 $ 0.03 Diluted EPU: Net income attributable to COPLP common unitholders $ 0.18 $ 0.03 Our diluted EPU computations do not include the effects of the following securities since the conversions of such securities would increase diluted EPU for the respective periods (in thousands): Weighted Average Units Excluded from Denominator For the Three Months Ended March 31, 2017 2016 Conversion of Series I preferred units 176 176 Conversion of Series K preferred units — 434 The following share-based compensation securities were excluded from the computation of diluted EPU because their effects were antidilutive: • weighted average restricted units and deferred share awards for the three months ended March 31, 2017 and 2016 of 392,000 and 405,000 , respectively; and • weighted average options for the three months ended March 31, 2017 and 2016 of 140,000 and 379,000 , respectively.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Litigation In the normal course of business, we are involved in legal actions arising from our ownership and administration of properties. We establish reserves for specific legal proceedings when we determine that the likelihood of an unfavorable outcome is probable and the amount of loss can be reasonably estimated. Management does not anticipate that any liabilities that may result from such proceedings will have a materially adverse effect on our financial position, operations or liquidity. Our assessment of the potential outcomes of these matters involves significant judgment and is subject to change based on future developments. Environmental We are subject to various Federal, state and local environmental regulations related to our property ownership and operation. We have performed environmental assessments of our properties, the results of which have not revealed any environmental liability that we believe would have a materially adverse effect on our financial position, operations or liquidity. Tax Incremental Financing Obligation In August 2010, Anne Arundel County, Maryland issued $30 million in tax incremental financing bonds to third-party investors in order to finance public improvements needed in connection with our project known as National Business Park North. The real estate taxes on increases in assessed value of a development district encompassing National Business Park North are to be transferred to a special fund pledged to the repayment of the bonds. We recognized a $1.5 million liability through March 31, 2017 representing our estimated obligation to fund through a special tax any future shortfalls between debt service on the bonds and real estate taxes available to repay the bonds. Operating Leases We are obligated as lessee under operating leases (mostly ground leases) with various expiration dates extending to the year 2100. Future minimum rental payments due under the terms of these operating leases as of March 31, 2017 follow (in thousands): Year Ending December 31, 2017 (1) $ 985 2018 1,290 2019 1,269 2020 1,261 2021 1,260 Thereafter 85,762 $ 91,827 (1) Represents the nine months ending December 31, 2017 . Contractual Obligations We had amounts remaining to be incurred under various contractual obligations as of March 31, 2017 that included the following: • new development and redevelopment obligations of $128.0 million ; • capital expenditures for operating properties of $51.8 million ; • third party construction and development of $6.7 million ; and • other obligations of $1.4 million . Environmental Indemnity Agreement In connection with a lease and subsequent sale in 2008 and 2010 of three properties in Dayton, New Jersey, we agreed to provide certain environmental indemnifications limited to $19 million in the aggregate. We have insurance coverage in place to mitigate much of any potential future losses that may result from these indemnification agreements.

Summary of Significant Accoun24

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2017
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The COPT consolidated financial statements include the accounts of COPT, the Operating Partnership, their subsidiaries and other entities in which COPT has a majority voting interest and control. The COPLP consolidated financial statements include the accounts of COPLP, its subsidiaries and other entities in which COPLP has a majority voting interest and control. We also consolidate certain entities when control of such entities can be achieved through means other than voting rights (“variable interest entities” or “VIEs”) if we are deemed to be the primary beneficiary of such entities. We eliminate all intercompany balances and transactions in consolidation. We use the equity method of accounting when we own an interest in an entity and can exert significant influence over but cannot control the entity’s operations. We discontinue equity method accounting if our investment in an entity (and net advances) is reduced to zero unless we have guaranteed obligations of the entity or are otherwise committed to provide further financial support for the entity. We use the cost method of accounting when we own an interest in an entity and cannot exert significant influence over its operations. These interim financial statements should be read together with the consolidated financial statements and notes thereto as of and for the year ended December 31, 2016 included in our 2016 Annual Report on Form 10-K. The unaudited consolidated financial statements include all adjustments that are necessary, in the opinion of management, to fairly state our financial position and results of operations. All adjustments are of a normal recurring nature. The consolidated financial statements have been prepared using the accounting policies described in our 2016 Annual Report on Form 10-K.
Reclassification, Policy [Policy Text Block]	Reclassification We reclassified certain amounts from prior periods to conform to the current period presentation of our consolidated financial statements with no effect on previously reported net income or equity.
Recent Accounting Pronouncement	Recent Accounting Pronouncements We adopted guidance issued by the Financial Accounting Standards Board (“FASB”) effective January 1, 2017 intended to simplify various aspects related to the accounting and presentation for employee share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities and classification on the consolidated statement of cash flows. In connection with our adoption of this policy, we made an entity-wide accounting policy election to continue to account for potential future award forfeitures by estimating the number of awards that are expected to vest. Our adoption of this guidance did not have a material impact on our consolidated financial statements. We adopted guidance issued by the FASB prospectively effective January 1, 2017 that clarifies the definition of a business used by entities in determining whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The definition of a business affects many areas of accounting including acquisitions, disposals, goodwill and consolidation. Under the new guidance it is expected that the majority of our future operating property acquisitions will be accounted for as asset acquisitions, whereas under the previous guidance our recent acquisitions were accounted for as business combinations; we believe that the primary effect of this change will be that transaction costs associated with future acquisitions will be capitalized rather than expensed as incurred. This guidance had no effect on our consolidated financial statements upon adoption. In May 2014, the FASB issued guidance regarding the recognition of revenue from contracts with customers. Under this guidance, an entity will recognize revenue to depict the transfer of goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This guidance also requires improved disclosures regarding the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. Also in connection with this guidance, in February 2017, the FASB issued additional guidance that clarifies the scope of asset derecognition guidance and accounting for partial sales of nonfinancial assets. While we are still completing our assessment of the impact of the guidance, below is a summary of the anticipated primary effects on our accounting and reporting. • Construction contract revenue: We reviewed our historical construction management arrangements and related contracts. Based on this review, we believe that we will account for these arrangements using the percentage of completion method, which is the method we have used in most cases historically. We do not currently believe that the resulting effect of the change will be material. • Sales of real estate: The new guidance requires recognition of a sale of real estate and resulting gain or loss when control transfers and the buyer has the ability to direct use of, or obtain substantially all of the remaining benefit from, the asset (which generally will occur on the closing date); the factor of continuing involvement is no longer a specific consideration for the timing of recognition. The new guidance eliminates the need to consider adequacy of buyer investment, which was replaced by additional judgments regarding collectability and intent and/or ability to pay. The new guidance also requires an entity to derecognize nonfinancial assets and in substance non financial assets once it transfers control of such assets. When an entity transfers its controlling interest in a nonfinancial asset, but retains a noncontrolling ownership interest, the entity is required to measure any non-controlling interest it receives or retains at fair value and recognize a full gain or loss on the transaction; as a result, sales and partial sales of real estate assets will now be subject to the same derecognition model as all other nonfinancial assets. Since all but one of our sale transactions previously met the criteria for immediate gain recognition under existing guidance, we do not believe that the recognition pattern for these transactions will be changed by the new guidance. Our one sale transaction that did not meet the criteria for immediate full recognition under the previous standard was our contribution of data center properties into a newly-formed joint venture in July 2016, as discussed further in our 2016 Annual Report on Form 10-K. We believe that this transaction, which was accounted for as a partial sale under existing guidance, would meet the criteria for immediate full gain recognition under the new guidance; this would result in an additional $18 million in income being recognizable in 2016 under the new guidance that is currently being amortized into income in subsequent periods under existing guidance. • Real estate revenue associated with executory costs and other non-lease components: Once the new guidance setting forth principles for the recognition, measurement, presentation and disclosure of leases (discussed below) goes into effect, we believe that the new revenue standard may apply to executory costs and other components of revenue due under leases that are deemed to be non-lease components (such as common area maintenance and provision of utilities), even when the revenue for such activities is not separately stipulated in the lease. In that case, then revenue from these items previously recognized on a straight-line basis under current lease guidance would be recognized under the new revenue guidance as the related services are delivered. As a result, while the total revenue recognized over time would not differ under the new guidance, the recognition pattern would be different. We are in the process of evaluating the significance of the difference in the recognition pattern that would result from this change. We are required to adopt this guidance for our annual and interim periods beginning January 1, 2018 using one of two methods: retrospective restatement for each reporting period presented at the time of adoption, or retrospectively with the cumulative effect of initially applying this guidance recognized at the date of initial application. We have not decided which method of adoption we will use. In February 2016, the FASB issued guidance that sets forth principles for the recognition, measurement, presentation and disclosure of leases. This guidance 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 of the leased asset by the lessee. The resulting classification determines whether the lease expense is recognized based on an effective interest method or straight-line basis over the term of the lease. 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 similar to existing guidance for operating leases. The guidance requires lessors of real estate to account for leases using an approach that is substantially equivalent to existing guidance for sales-type leases, direct financing leases and operating leases. While we are still completing our assessment of the impact of this guidance, below is a summary of the anticipated primary effects of this guidance on our accounting and reporting. • Real estate leases in which we are the lessor: ◦ Balance sheet reporting: We believe that we will apply an approach under the new guidance that is similar to the current accounting for operating leases, in which we will continue to recognize the underlying leased asset as property on our balance sheet. ◦ Deferral of compensation-related lease costs: Under the new lease guidance, lessors may only capitalize their incremental direct costs of leasing. As a result, we believe that we will no longer be able to defer the recognition of compensation-related costs in connection with new or extended tenant leases (refer to amounts reported in our 2016 Annual Report on Form 10-K for amounts deferred in 2014, 2015 and 2016). ◦ Lease revenue reporting: As discussed in further detail above in connection with the new revenue guidance, we believe that the new revenue standard may apply to executory costs and other components of revenue deemed to be non-lease components (such as common area maintenance and provision of utilities), even when the revenue for such activities is not separately stipulated in the lease. In that case, we would need to separate the lease components of revenue due under leases from the non-lease components. Under the new guidance, we would continue to recognize the lease components of lease revenue on a straight-line basis over our respective lease terms as we do under prior guidance. However, we would recognize the non-lease components under the new revenue guidance as the related services are delivered. As discussed above, we are in the process of evaluating the significance of the difference in the recognition pattern that would result from this change. • Leases in which we are the lessee: ◦ Our most significant leases as lessee are ground leases we have for certain properties; as of March 31, 2017 , our future minimum rental payments under these leases totaled $90.7 million , with various expiration dates extending to the year 2100. While we are still in the process of evaluating these leases under the new guidance, we believe that we will be required to recognize a right-of-use asset and a lease liability for the present value of these minimum lease payments. We believe that these leases most likely will be classified as finance leases under the new guidance; as a result, the interest component of each lease payment would be recorded as interest expense and the right-of-use asset would be amortized into expense using the straight-line method over the life of the lease. This guidance is effective for reporting periods beginning January 1, 2019, with modified retrospective restatement for each reporting period presented at the time of adoption. Early adoption is also permitted for this guidance. In June 2016, the FASB issued guidance that changes how entities measure credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. The guidance replaces the current incurred loss model with an expected loss approach, resulting in a more timely recognition of such losses. The guidance will apply to most financial assets measured at amortized cost and certain other instruments, including trade and other receivables, loans, held-to-maturity debt securities, net investments in leases, and off-balance-sheet credit exposures (e.g. loan commitments). Under the new guidance, an entity will recognize its estimate of expected credit losses as an allowance, as the guidance requires that financial assets be measured on an amortized cost basis and to be presented at the net amount expected to be collected. The guidance is effective for us beginning January 1, 2020, with early adoption permitted after December 2018. We are currently assessing the financial impact of this guidance on our consolidated financial statements. In August 2016, the FASB issued guidance that clarifies how entities should classify certain cash receipts and cash payments on the statement of cash flows with the objective of reducing the existing diversity in practice related to eight specific cash flow issues. The areas addressed in the new guidance relate to debt prepayment costs, settlement of zero-coupon debt instruments, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of corporate-owned and bank-owned life insurance policies, distributions received from equity method investments, beneficial interest in securitization transactions and separately identifiable cash flows and application of the predominance principle. The guidance is effective for us beginning January 1, 2018, with early adoption permitted. We do not expect the adoption of this guidance to have a material impact on our consolidated financial statements. In November 2016, the FASB issued guidance that requires the statement of cash flows to explain the change during the period in the total of cash, cash equivalents and amounts described as restricted cash or restricted cash equivalents. Under the new guidance, amounts described as restricted cash and restricted cash equivalents will be included with cash and cash equivalents when reconciling the beginning of period and end of period total amounts shown on the statement of cash flows. The guidance is effective for us beginning January 1, 2018, with early adoption permitted. We do not expect the adoption of this guidance to have a material impact on our consolidated financial statements.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2017
Fair Value Disclosures [Abstract]
Schedule of fair value assets and liabilities measured on recurring basis	The table below sets forth financial assets and liabilities of COPLP and its subsidiaries that are accounted for at fair value on a recurring basis as of March 31, 2017 and the hierarchy level of inputs used in measuring their respective fair values under applicable accounting standards (in thousands): Description Quoted Prices in Significant Other Significant Total Assets: Interest rate derivatives (1) $ — $ 1,183 $ — $ 1,183 Liabilities: Interest rate derivatives (2) $ — $ 735 $ — $ 735 (1) Included in the line entitled “prepaid expenses and other assets” on COPLP ’ s consolidated balance sheet. (2) Included in the line entitled “other liabilities” on COPLP ’ s consolidated balance sheet. The table below sets forth financial assets and liabilities of COPT and its subsidiaries that are accounted for at fair value on a recurring basis as of March 31, 2017 and the hierarchy level of inputs used in measuring their respective fair values under applicable accounting standards (in thousands): Description Quoted Prices in Significant Other Significant Total Assets: Marketable securities in deferred compensation plan (1) Mutual funds $ 4,075 $ — $ — $ 4,075 Other 76 — — 76 Interest rate derivatives (2) — 1,183 — 1,183 Total assets $ 4,151 $ 1,183 $ — $ 5,334 Liabilities: Deferred compensation plan liability (3) $ — $ 4,151 $ — $ 4,151 Interest rate derivatives (3) — 735 — 735 Total liabilities $ — $ 4,886 $ — $ 4,886 (1) Included in the line entitled “restricted cash and marketable securities” on COPT’s consolidated balance sheet. (2) Included in the line entitled “prepaid expenses and other assets” on COPT ’ s consolidated balance sheet. (3) Included in the line entitled “other liabilities” on COPT’s consolidated balance sheet.
Schedule of fair value hierarchy of impaired properties and other assets associated with such properties	The table below sets forth the fair value hierarchy of the valuation technique we used to determine nonrecurring fair value measurements of properties held for sale as of March 31, 2017 (dollars in thousands): Fair Values as of March 31, 2017 Quoted Prices in Significant Active Markets for Significant Other Unobservable Identical Assets Observable Inputs Inputs Description (Level 1) (Level 2) (Level 3) Total Assets: Assets held for sale, net $ — $ — $ 40,086 $ 40,086
Schedule of quantitative information about significant unobservable inputs used for Level 3 fair value measurements	The table below sets forth quantitative information about significant unobservable inputs used for the Level 3 fair value measurements reported above as of March 31, 2017 (dollars in thousands): Valuation Technique Fair Values on Measurement Date Unobservable Input Range (Weighted Average) Discounted cash flow $ 37,604 Discount rate 9.3% - 11.3% (10.1%) Terminal capitalization rate 8.3% - 11.4% (8.6%) Yield analyses $ 2,482 Investor yield requirement 9.0% (1) (1) Only one fair value applied for this unobservable input.

Properties, Net (Tables)

Properties, Net (Tables)	3 Months Ended
	Mar. 31, 2017
Real Estate [Abstract]
Schedule of operating properties, net	Operating properties, net consisted of the following (in thousands): March 31, December 31, Land $ 430,364 $ 433,311 Buildings and improvements 2,972,164 2,944,905 Less: Accumulated depreciation (732,371 ) (706,385 ) Operating properties, net $ 2,670,157 $ 2,671,831
Schedule of projects in development or held for future development	Projects in development or held for future development consisted of the following (in thousands): March 31, December 31, Land $ 195,727 $ 195,521 Development in progress, excluding land 227,130 206,010 Projects in development or held for future development $ 422,857 $ 401,531
Components of assets held for sale	The table below sets forth the components of assets held for sale on our consolidated balance sheet for these properties (in thousands): March 31, 2017 December 31, 2016 Properties, net $ 38,018 $ 85,402 Deferred rent receivable 1,546 4,241 Intangible assets on real estate acquisitions, net 338 338 Deferred leasing costs, net 1,109 3,636 Lease incentives, net 380 1,037 Assets held for sale, net $ 41,391 $ 94,654

Real Estate Joint Ventures (Tab

Real Estate Joint Ventures (Tables)	3 Months Ended
	Mar. 31, 2017
Equity Method Investments and Joint Ventures [Abstract]
Schedule of information related to investments in consolidated real estate joint ventures	The table below sets forth information pertaining to our investments in consolidated real estate joint ventures as of March 31, 2017 (dollars in thousands): Nominal Ownership March 31, 2017 (1) Date % as of Total Encumbered Total Acquired 3/31/2017 Nature of Activity Assets Assets Liabilities LW Redstone Company, LLC 3/23/2010 85% Development and operation of real estate (2) $ 157,293 $ 78,251 $ 50,804 M Square Associates, LLC 6/26/2007 50% Development and operation of real estate (3) 65,158 46,124 45,712 Stevens Investors, LLC 8/11/2015 95% Development of real estate (4) 42,176 — 7,252 $ 264,627 $ 124,375 $ 103,768 (1) Excludes amounts eliminated in consolidation. (2) This joint venture’s properties are in Huntsville, Alabama. (3) This joint venture’s properties are in College Park, Maryland. (4) This joint venture’s property is in Washington, DC. Our partner in this joint venture is entitled to receive an additional distribution from the joint venture of $6.7 million to be funded by us (expected by 2018) that was reported in other liabilities on our consolidated balance sheet as of March 31, 2017 .

Investing Receivables (Tables)

Investing Receivables (Tables)	3 Months Ended
	Mar. 31, 2017
Receivables [Abstract]
Schedule of investing receivables	Investing receivables, including accrued interest thereon, consisted of the following (in thousands): March 31, December 31, Notes receivable from the City of Huntsville $ 50,570 $ 49,258 Other investing loans receivable 3,000 3,021 $ 53,570 $ 52,279

Prepaid Expenses and Other As29

Prepaid Expenses and Other Assets, Net (Tables)	3 Months Ended
	Mar. 31, 2017
Prepaid Expense and Other Assets [Abstract]
Schedule of prepaid expenses and other assets	Prepaid expenses and other assets, net consisted of the following (in thousands): March 31, December 31, Lease incentives, net $ 17,516 $ 18,276 Prepaid expenses 17,332 24,432 Furniture, fixtures and equipment, net 4,989 5,204 Construction contract costs incurred in excess of billings 4,451 10,350 Deferred tax asset, net (1) 2,980 3,036 Deferred financing costs, net (2) 2,444 3,128 Non-real estate equity method investments 2,353 2,355 Other assets 7,658 5,983 Prepaid expenses and other assets, net $ 59,723 $ 72,764 (1) Includes a valuation allowance of $2.1 million . (2) Represents deferred costs, net of accumulated amortization, attributable to our Revolving Credit Facility and interest rate derivatives.

Debt, Net (Tables)

Debt, Net (Tables)	3 Months Ended
	Mar. 31, 2017
Debt Disclosure [Abstract]
Schedule of debt	Our debt consisted of the following (dollars in thousands): Carrying Value (1) as of March 31, December 31, Stated Interest Rates as of Scheduled Maturity as of March 31, 2017 March 31, 2017 Mortgage and Other Secured Debt: Fixed rate mortgage debt (2) $ 153,294 $ 154,143 3.82% - 7.87% (3) 2019-2026 Variable rate secured debt 13,365 13,448 LIBOR + 1.85% (4) October 2020 Total mortgage and other secured debt 166,659 167,591 Revolving Credit Facility — — LIBOR + 0.875% to 1.60% May 2019 Term Loan Facilities (5) 547,682 547,494 LIBOR + 0.90% to 2.40% (6) 2020-2022 Unsecured Senior Notes 3.600%, $350,000 aggregate principal 347,233 347,128 3.60% (7) May 2023 5.250%, $250,000 aggregate principal 246,291 246,176 5.25% (8) February 2024 3.700%, $300,000 aggregate principal 297,961 297,843 3.70% (9) June 2021 5.000%, $300,000 aggregate principal 296,457 296,368 5.00% (10) July 2025 Unsecured notes payable 1,374 1,401 0% (11) 2026 Total debt, net $ 1,903,657 $ 1,904,001 (1) The carrying values of our debt other than the Revolving Credit Facility reflect net deferred financing costs of $5.7 million as of March 31, 2017 and $6.1 million as of December 31, 2016 . (2) Certain fixed rate mortgages carry interest rates that were above or below market rates upon assumption and therefore were recorded at their fair value based on applicable effective interest rates. The carrying values of these loans reflect net unamortized premiums totaling $403,000 as of March 31, 2017 and $422,000 as of December 31, 2016 . (3) The weighted average interest rate on our fixed rate mortgage debt was 4.19% as of March 31, 2017 . (4) The interest rate on our variable rate secured debt as of March 31, 2017 was 2.63% . (5) As of March 31, 2017 , we have the ability to borrow an additional $350.0 million in the aggregate under these term loan facilities, provided that there is no default under the facilities and subject to the approval of the lenders. (6) The weighted average interest rate on these loans was 2.37% as of March 31, 2017 . (7) The carrying value of these notes reflects an unamortized discount totaling $1.9 million as of March 31, 2017 and $2.0 million as of December 31, 2016 . The effective interest rate under the notes, including amortization of the issuance costs, was 3.70% . (8) The carrying value of these notes reflects an unamortized discount totaling $3.3 million as of March 31, 2017 and $3.4 million as of December 31, 2016 . The effective interest rate under the notes, including amortization of the issuance costs, was 5.49% . (9) The carrying value of these notes reflects an unamortized discount totaling $1.6 million as of March 31, 2017 and $1.7 million as of December 31, 2016 . The effective interest rate under the notes, including amortization of the issuance costs, was 3.85% . (10) The carrying value of these notes reflects an unamortized discount totaling $2.9 million as of March 31, 2017 and $3.0 million as of December 31, 2016 . The effective interest rate under the notes, including amortization of the issuance costs, was 5.15% . (11) These notes carry interest rates that were below market rates upon assumption and therefore were recorded at their fair value based on applicable effective interest rates. The carrying value of these notes reflects an unamortized discount totaling $438,000 as of March 31, 2017 and $460,000 as of December 31, 2016 .
Schedule of the fair value of debt	The following table sets forth information pertaining to the fair value of our debt (in thousands): March 31, 2017 December 31, 2016 Carrying Estimated Carrying Estimated Amount Fair Value Amount Fair Value Fixed-rate debt Unsecured Senior Notes $ 1,187,942 $ 1,223,753 $ 1,187,515 $ 1,220,282 Other fixed-rate debt 154,668 156,098 155,544 156,887 Variable-rate debt 561,047 556,844 560,942 558,437 $ 1,903,657 $ 1,936,695 $ 1,904,001 $ 1,935,606

Interest Rate Derivatives (Tabl

Interest Rate Derivatives (Tables)	3 Months Ended
	Mar. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of key terms and fair values of interest rate swap derivatives	The following table sets forth the key terms and fair values of our interest rate swap derivatives (dollars in thousands): Fair Value at Notional Amount Fixed Rate Floating Rate Index Effective Date Expiration Date March 31, December 31, $ 100,000 1.6730% One-Month LIBOR 9/1/2015 8/1/2019 $ (301 ) $ (701 ) 100,000 1.7300% One-Month LIBOR 9/1/2015 8/1/2019 (434 ) (848 ) 13,494 (1) 1.3900% One-Month LIBOR 10/13/2015 10/1/2020 147 100 100,000 1.9013% One-Month LIBOR 9/1/2016 12/1/2022 409 (23 ) 100,000 1.9050% One-Month LIBOR 9/1/2016 12/1/2022 427 48 50,000 1.9079% One-Month LIBOR 9/1/2016 12/1/2022 200 10 $ 448 $ (1,414 ) (1) The notional amount of this instrument is scheduled to amortize to $12.1 million .
Schedule of fair value and balance sheet classification of interest rate derivatives	The table below sets forth the fair value of our interest rate derivatives as well as their classification on our consolidated balance sheets (in thousands): Fair Value at Derivatives Balance Sheet Location March 31, December 31, 2016 Interest rate swaps designated as cash flow hedges Prepaid expenses and other assets $ 1,183 $ 158 Interest rate swaps designated as cash flow hedges Other liabilities (735 ) (1,572 )
Schedule of effect of interest rate derivatives on consolidated statements of operations and comprehensive income	The table below presents the effect of our interest rate derivatives on our consolidated statements of operations and comprehensive income (in thousands): For the Three Months Ended March 31, 2017 2016 Amount of gain (loss) recognized in accumulated other comprehensive loss (“AOCL”) (effective portion) $ 224 $ (11,284 ) Amount of losses reclassified from AOCL into interest expense (effective portion) (1,184 ) (870 ) Amount of gain (loss) recognized in interest expense (ineffective portion) 454 (1,551 )

Redeemable Noncontrolling Int32

Redeemable Noncontrolling Interests (Tables)	3 Months Ended
	Mar. 31, 2017
Noncontrolling Interest [Abstract]
Schedule of activity for redeemable noncontrolling interest	The table below sets forth the activity for these redeemable noncontrolling interests (in thousands): For the Three Months Ended March 31, 2017 2016 Beginning balance $ 22,979 $ 19,218 Contributions from noncontrolling interests — 22,779 Distributions to noncontrolling interests (415 ) (20,526 ) Net income attributable to noncontrolling interests 567 560 Adjustment to arrive at fair value of interests 545 302 Ending balance $ 23,676 $ 22,333

Information by Business Segme33

Information by Business Segment (Tables)	3 Months Ended
	Mar. 31, 2017
Segment Reporting [Abstract]
Schedule of segment financial information for real estate operations	The table below reports segment financial information for our reportable segments (in thousands): Operating Office Property Segments Defense/Information Technology Locations Fort Meade/BW Corridor Northern Virginia Defense/IT Lackland Air Force Base Navy Support Locations Redstone Arsenal Data Center Shells Total Defense/IT Locations Regional Office Operating Other Total Three Months Ended March 31, 2017 Revenues from real estate operations $ 60,855 $ 11,707 $ 11,634 $ 7,010 $ 3,460 $ 5,522 $ 100,188 $ 18,276 $ 6,770 $ 1,533 $ 126,767 Property operating expenses (20,520 ) (4,452 ) (6,802 ) (3,209 ) (1,371 ) (659 ) (37,013 ) (7,486 ) (3,365 ) (655 ) (48,519 ) UJV NOI allocable to COPT — — — — — 1,298 1,298 — — — 1,298 NOI from real estate operations $ 40,335 $ 7,255 $ 4,832 $ 3,801 $ 2,089 $ 6,161 $ 64,473 $ 10,790 $ 3,405 $ 878 $ 79,546 Additions to long-lived assets $ 3,422 $ 2,468 $ — $ 2,168 $ 132 $ — $ 8,190 $ 7,120 $ 1,574 $ 156 $ 17,040 Transfers from non-operating properties $ 13,416 $ 222 $ — $ — $ (4 ) $ (1,015 ) $ 12,619 $ — $ 8 $ 18 $ 12,645 Segment assets at March 31, 2017 $ 1,258,437 $ 361,449 $ 131,194 $ 195,892 $ 109,171 $ 206,489 $ 2,262,632 $ 439,079 $ 229,630 $ 21,011 $ 2,952,352 Three Months Ended March 31, 2016 Revenues from real estate operations $ 62,509 $ 12,116 $ 10,225 $ 6,934 $ 3,116 $ 6,330 $ 101,230 $ 23,502 $ 6,493 $ 1,862 $ 133,087 Property operating expenses (23,246 ) (4,541 ) (5,420 ) (3,524 ) (978 ) (810 ) (38,519 ) (9,831 ) (2,661 ) (864 ) (51,875 ) NOI from real estate operations $ 39,263 $ 7,575 $ 4,805 $ 3,410 $ 2,138 $ 5,520 $ 62,711 $ 13,671 $ 3,832 $ 998 $ 81,212 Additions to long-lived assets $ 6,519 $ 3,078 $ — $ 1,270 $ 618 $ — $ 11,485 $ 2,759 $ — $ 157 $ 14,401 Transfers from non-operating properties $ 35,751 $ (94 ) $ 6 $ — $ 211 $ 26,097 $ 61,971 $ 82 $ 51 $ (11 ) $ 62,093 Segment assets at March 31, 2016 $ 1,319,444 $ 407,199 $ 133,757 $ 195,306 $ 107,693 $ 227,808 $ 2,391,207 $ 603,662 $ 240,484 $ 70,039 $ 3,305,392
Schedule of reconciliation of segment revenues to total revenues	The following table reconciles our segment revenues to total revenues as reported on our consolidated statements of operations (in thousands): For the Three Months Ended March 31, 2017 2016 Segment revenues from real estate operations $ 126,767 $ 133,087 Construction contract and other service revenues 13,034 11,220 Total revenues $ 139,801 $ 144,307
Schedule of reconciliation of unconsolidated joint venture net operating income to equity in income of unconsolidated entities	The following table reconciles UJV NOI allocable to COPT to equity in income of unconsolidated entities as reported on our consolidated statements of operations (in thousands): For the Three Months Ended March 31, 2017 2016 UJV NOI allocable to COPT $ 1,298 $ — Less: Income from UJV allocable to COPT attributable to depreciation and amortization expense and interest expense (572 ) — Add: Equity in (loss) income of unconsolidated non-real estate entities (1 ) 10 Equity in income of unconsolidated entities $ 725 $ 10
Schedule of computation of net operating income from service operations	The table below sets forth the computation of our NOI from service operations (in thousands): For the Three Months Ended March 31, 2017 2016 Construction contract and other service revenues $ 13,034 $ 11,220 Construction contract and other service expenses (12,486 ) (10,694 ) NOI from service operations $ 548 $ 526
Schedule of reconciliation of net operating income from real estate operations and service operations to (loss) income from continuing operations	The following table reconciles our NOI from real estate operations for reportable segments and NOI from service operations to income from before gain on sales of real estate as reported on our consolidated statements of operations (in thousands): For the Three Months Ended March 31, 2017 2016 NOI from real estate operations $ 79,546 $ 81,212 NOI from service operations 548 526 Interest and other income 1,726 1,156 Equity in income of unconsolidated entities 725 10 Income tax (expense) benefit (40 ) 8 Depreciation and other amortization associated with real estate operations (33,059 ) (34,527 ) Impairment losses — (2,446 ) General, administrative and leasing expenses (8,611 ) (11,883 ) Business development expenses and land carry costs (1,693 ) (2,418 ) Interest expense (18,994 ) (23,559 ) Less: UJV NOI allocable to COPT included in equity in income of unconsolidated entities (1,298 ) — Gain on early extinguishment of debt — 17 Income before gain on sales of real estate $ 18,850 $ 8,096
Schedule of reconciliation of segment assets to total assets	The following table reconciles our segment assets to the consolidated total assets of COPT and subsidiaries (in thousands): March 31, March 31, Segment assets $ 2,952,352 $ 3,305,392 Non-operating property assets 429,690 444,334 Other assets 357,324 188,182 Total COPT consolidated assets $ 3,739,366 $ 3,937,908

Share-Based Compensation and 34

Share-Based Compensation and Other Compensation Matters (Tables)	3 Months Ended
	Mar. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of payouts for defined performance under performance-based awards of share-based compensation	The number of PSUs earned (“earned PSUs”) at the end of the performance period will be determined based on the percentile rank of COPT’s total shareholder return relative to a peer group of companies, as set forth in the following schedule: Percentile Rank Earned PSUs Payout % 75th or greater 200% of PSUs granted 50th or greater 100% of PSUs granted 25th 50% of PSUs granted Below 25th 0% of PSUs granted

Earnings Per Share ("EPS") an35

Earnings Per Share ("EPS") and Earnings Per Unit ("EPU") (Tables)	3 Months Ended
	Mar. 31, 2017
Earnings Per Share [Line Items]
Summary of calculation of numerator and denominator in basic and diluted earnings per share	Summaries of the numerator and denominator for purposes of basic and diluted EPS calculations are set forth below (in thousands, except per share data): For the Three Months Ended March 31, 2017 2016 Numerator: Net income attributable to COPT $ 21,355 $ 6,826 Preferred share dividends (3,180 ) (3,552 ) Income attributable to share-based compensation awards (125 ) (118 ) Numerator for basic and diluted EPS on net income attributable to COPT common shareholders $ 18,050 $ 3,156 Denominator (all weighted averages): Denominator for basic EPS (common shares) 98,411 94,203 Dilutive effect of share-based compensation awards 155 95 Denominator for diluted EPS (common shares) 98,566 94,298 Basic EPS: Net income attributable to COPT common shareholders $ 0.18 $ 0.03 Diluted EPS: Net income attributable to COPT common shareholders $ 0.18 $ 0.03
Schedule of securities excluded from computation of diluted earnings per share	Our diluted EPS computations do not include the effects of the following securities since the conversions of such securities would increase diluted EPS for the respective periods (in thousands): Weighted Average Shares Excluded from Denominator For the Three Months Ended March 31, 2017 2016 Conversion of common units 3,446 3,677 Conversion of Series I Preferred Units 176 176 Conversion of Series K Preferred Shares — 434
Corporate Office Properties, L.P.
Earnings Per Share [Line Items]
Summary of calculation of numerator and denominator in basic and diluted earnings per share	Summaries of the numerator and denominator for purposes of basic and diluted EPU calculations are set forth below (in thousands, except per unit data): For the Three Months Ended March 31, 2017 2016 Numerator: Net income attributable to COPLP common unitholders $ 22,154 $ 7,117 Preferred unit distributions (3,345 ) (3,717 ) Income attributable to share-based compensation awards (125 ) (118 ) Numerator for basic and diluted EPU on net income attributable to COPLP common unitholders $ 18,684 $ 3,282 Denominator (all weighted averages): Denominator for basic EPU (common units) 101,857 97,880 Dilutive effect of share-based compensation awards 155 95 Denominator for diluted EPU (common units) 102,012 97,975 Basic EPU: Net income attributable to COPLP common unitholders $ 0.18 $ 0.03 Diluted EPU: Net income attributable to COPLP common unitholders $ 0.18 $ 0.03
Schedule of securities excluded from computation of diluted earnings per share	Our diluted EPU computations do not include the effects of the following securities since the conversions of such securities would increase diluted EPU for the respective periods (in thousands): Weighted Average Units Excluded from Denominator For the Three Months Ended March 31, 2017 2016 Conversion of Series I preferred units 176 176 Conversion of Series K preferred units — 434

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Future minimum rental payments for operating leases	Future minimum rental payments due under the terms of these operating leases as of March 31, 2017 follow (in thousands): Year Ending December 31, 2017 (1) $ 985 2018 1,290 2019 1,269 2020 1,261 2021 1,260 Thereafter 85,762 $ 91,827 (1) Represents the nine months ending December 31, 2017 .

Organization (Details)

Organization (Details) ft² in Thousands	Mar. 31, 2017aft²PropertyMW
Properties under or approved for redevelopment
Investments in real estate
Number of real estate properties	1
Area of real estate property (in square feet or acres) | ft²	14
Operating office properties
Investments in real estate
Number of real estate properties	164
Area of real estate property (in square feet or acres) | ft²	17,100
Operating office properties | Single-tenant data centers
Investments in real estate
Number of real estate properties	13
Office properties under, or contractually committed for, construction or approved for redevelopment
Investments in real estate
Number of real estate properties	9
Area of real estate property (in square feet or acres) | ft²	1,300
Office properties under, or contractually committed for, construction or approved for redevelopment | Properties completed Held-for-future lease
Investments in real estate
Number of real estate properties	2
Partially operational properties | Properties under or approved for redevelopment
Investments in real estate
Number of real estate properties	2
Land controlled for future development
Investments in real estate
Area of real estate property (in square feet or acres) | a	987
Developable square feet | ft²	12,200
Other Land
Investments in real estate
Area of real estate property (in square feet or acres) | a	194
Operating wholesale data centers
Investments in real estate
Critical load (in megawatts) | MW	19.25
GI-COPT | Operating office properties | Single-tenant data centers
Investments in real estate
Number of real estate properties	6

Organization (Details 2)

Organization (Details 2) - Corporate Office Properties, L.P.	3 Months Ended
	Mar. 31, 2017
Common Units
Forms of ownership in Operating Partnership and ownership percentage by the entity
Percentage ownership in operating partnership	96.70%
Preferred Units
Forms of ownership in Operating Partnership and ownership percentage by the entity
Percentage ownership in operating partnership	95.10%

Summary of Significant Accoun39

Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Mar. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Minimum rental payments due		$ 91,827
Ground Leases
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Minimum rental payments due		$ 90,700
Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Effect of change on net income	$ 18,000

Fair Value Measurements (Detail

Fair Value Measurements (Details) - Deferred compensation plan - Management $ in Millions	3 Months Ended
	Mar. 31, 2017USD ($)
Assets and liabilities measured at fair value on a recurring basis
Maximum percentage of participants' compensation which is deferrable (as a percent)	100.00%
Balance of the plan which was fully funded	$ 4.2

Fair Value Measurements (Deta41

Fair Value Measurements (Details 2) - Fair value measurement on a recurring basis $ in Thousands	Mar. 31, 2017USD ($)
Assets:
Interest rate derivatives	$ 1,183
Total assets	5,334
Liabilities:
Deferred compensation plan liability	4,151
Interest rate derivatives	735
Liabilities	4,886
Mutual funds
Assets:
Marketable securities in deferred compensation plan	4,075
Other
Assets:
Marketable securities in deferred compensation plan	76
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Total assets	4,151
Quoted Prices in Active Markets for Identical Assets (Level 1) | Mutual funds
Assets:
Marketable securities in deferred compensation plan	4,075
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other
Assets:
Marketable securities in deferred compensation plan	76
Significant Other Observable Inputs (Level 2)
Assets:
Interest rate derivatives	1,183
Total assets	1,183
Liabilities:
Deferred compensation plan liability	4,151
Interest rate derivatives	735
Liabilities	4,886
Corporate Office Properties, L.P.
Assets:
Interest rate derivatives	1,183
Liabilities:
Interest rate derivatives	735
Corporate Office Properties, L.P. | Significant Other Observable Inputs (Level 2)
Assets:
Interest rate derivatives	1,183
Liabilities:
Interest rate derivatives	$ 735

Fair Value Measurements (Deta42

Fair Value Measurements (Details 3) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Assets and liabilities measured at fair value on a non-recurring basis
Assets held for sale, net	$ 41,391		$ 94,654
Impairment losses	0	$ 2,446
Assets held for sale, net
Assets and liabilities measured at fair value on a non-recurring basis
Assets held for sale, net	$ 41,391		$ 94,654

Fair Value Measurements (Deta43

Fair Value Measurements (Details 4) - Fair value measurement on a nonrecurring basis $ in Thousands	3 Months Ended
	Mar. 31, 2017USD ($)
Significant Unobservable Inputs (Level 3) | Discounted cash flow
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Values on Measurement Date	$ 37,604
Significant Unobservable Inputs (Level 3) | Yield analyses
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Values on Measurement Date	$ 2,482
Investor yield requirement (percent)	9.00%
Assets held for sale, net
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Values on Measurement Date	$ 40,086
Assets held for sale, net | Significant Unobservable Inputs (Level 3)
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Values on Measurement Date	$ 40,086
Minimum | Significant Unobservable Inputs (Level 3) | Discounted cash flow
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount rate (percent)	9.30%
Terminal capitalization rate (percent)	8.30%
Maximum | Significant Unobservable Inputs (Level 3) | Discounted cash flow
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount rate (percent)	11.30%
Terminal capitalization rate (percent)	11.40%
Weighted Average | Significant Unobservable Inputs (Level 3) | Discounted cash flow
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount rate (percent)	10.10%
Terminal capitalization rate (percent)	8.60%

Properties, Net (Details)

Properties, Net (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Investments in real estate
Operating properties, net	$ 2,670,157	$ 2,671,831
Operating Properties
Investments in real estate
Less: accumulated depreciation	(732,371)	(706,385)
Operating properties, net	2,670,157	2,671,831
Operating Properties | Land
Investments in real estate
Gross	430,364	433,311
Operating Properties | Buildings and improvements
Investments in real estate
Gross	$ 2,972,164	$ 2,944,905

Properties, Net (Details 2)

Properties, Net (Details 2) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Properties
Projects in development or held for future development	$ 422,857	$ 401,531
Projects in development or held for future development | Land in development or held for future development
Properties
Projects in development or held for future development	195,727	195,521
Projects in development or held for future development | Construction in progress, excluding land
Properties
Projects in development or held for future development	$ 227,130	$ 206,010

Properties, Net (Details 3)

Properties, Net (Details 3) $ in Thousands	Mar. 31, 2017USD ($)Property	Dec. 31, 2016USD ($)Property
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets held for sale, net	$ 41,391	$ 94,654
Assets held for sale, net
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Properties, net	38,018	85,402
Deferred rent receivable	1,546	4,241
Intangible assets on real estate acquisitions, net	338	338
Deferred leasing costs, net	1,109	3,636
Lease incentives, net	380	1,037
Assets held for sale, net	$ 41,391	$ 94,654
Regional Office | White Marsh, Maryland | Assets held for sale, net
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties | Property	6	8
Defense/Information Technology Locations | Northern Virginia Defense/IT | Assets held for sale, net
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties | Property		1
Defense/Information Technology Locations | Fort Meade/BW Corridor | Assets held for sale, net
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties | Property	1

Properties, Net (Details 4)

Properties, Net (Details 4) ft² in Thousands, $ in Millions	Feb. 15, 2017USD ($)ft²	Mar. 31, 2017USD ($)ft²Property
Construction and Redevelopment Activities
Sale price of land | $		$ 14.3
Gain on sale of land | $		$ 4.2
Office properties under, or contractually committed for, construction or approved for redevelopment
Construction and Redevelopment Activities
Square footage of real estate properties (in square feet) | ft²		1,300
Number of real estate properties | Property		9
Newly redeveloped properties placed in service
Construction and Redevelopment Activities
Square feet of properties placed in service | ft²		86
Number of real estate properties | Property		3
Properties under construction or contractually committed for construction
Construction and Redevelopment Activities
Square footage of real estate properties (in square feet) | ft²		1,300
Number of real estate properties | Property		8
Properties completed Held-for-future lease | Office properties under, or contractually committed for, construction or approved for redevelopment
Construction and Redevelopment Activities
Number of real estate properties | Property		2
Properties under or approved for redevelopment
Construction and Redevelopment Activities
Square footage of real estate properties (in square feet) | ft²		14
Number of real estate properties | Property		1
Operating Properties | Northern Virginia Defense/IT | Defense/Information Technology Locations | 3120 Fairview Park Drive
Construction and Redevelopment Activities
Square footage of real estate properties (in square feet) | ft²	190
Transaction value | $	$ 39

Real Estate Joint Ventures (Det

Real Estate Joint Ventures (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017USD ($)Property	Dec. 31, 2016USD ($)
Investments in consolidated real estate joint ventures
Non-real estate equity method investments	$ 2,353	$ 2,355
GI-COPT
Investments in consolidated real estate joint ventures
Non-real estate equity method investments	25,400
Maximum amount at risk	17,800
Consolidated real estate joint ventures
Investments in consolidated real estate joint ventures
Total Assets	264,627
Encumbered Assets	124,375
Total Liabilities	$ 103,768
Variable Interest Entity, Primary Beneficiary | LW Redstone Company, LLC
Investments in consolidated real estate joint ventures
Ownership (as a percent)	85.00%
Total Assets	$ 157,293
Encumbered Assets	78,251
Total Liabilities	$ 50,804
Variable Interest Entity, Primary Beneficiary | M Square Associates, LLC
Investments in consolidated real estate joint ventures
Ownership (as a percent)	50.00%
Total Assets	$ 65,158
Encumbered Assets	46,124
Total Liabilities	$ 45,712
Variable Interest Entity, Primary Beneficiary | Stevens Investors, LLC
Investments in consolidated real estate joint ventures
Ownership (as a percent)	95.00%
Total Assets	$ 42,176
Encumbered Assets	0
Total Liabilities	7,252
Variable Interest Entity, Primary Beneficiary | Stevens Investors, LLC | Other Liabilities
Investments in consolidated real estate joint ventures
Due to Affiliate	$ 6,700
Operating office properties
Investments in consolidated real estate joint ventures
Number of real estate properties | Property	164
Single-tenant data centers | Operating office properties
Investments in consolidated real estate joint ventures
Number of real estate properties | Property	13
Single-tenant data centers | Operating office properties | GI-COPT
Investments in consolidated real estate joint ventures
Ownership percentage (percent)	50.00%
Number of real estate properties | Property	6

Investing Receivables (Details)

Investing Receivables (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Investing receivables	$ 53,570	$ 52,279
Notes Receivable from City of Huntsville
Accounts, Notes, Loans and Financing Receivable [Line Items]
Investing receivables	$ 50,570	49,258
Notes Receivable from City of Huntsville | LW Redstone Company, LLC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Stated interest rate (as a percent)	9.95%
Other investing loans receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Investing receivables	$ 3,000	$ 3,021

Prepaid Expenses and Other As50

Prepaid Expenses and Other Assets, Net (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Prepaid Expense and Other Assets [Abstract]
Lease incentives, net	$ 17,516	$ 18,276
Prepaid expenses	17,332	24,432
Furniture, fixtures and equipment, net	4,989	5,204
Construction contract costs incurred in excess of billings	4,451	10,350
Deferred tax asset, net	2,980	3,036
Deferred financing costs, net	2,444	3,128
Non-real estate equity method investments	2,353	2,355
Other assets	7,658	5,983
Prepaid expenses and other assets, net	59,723	72,764
Taxable REIT Subsidiary
Mortgage and Other Investing Receivables [Line Items]
Deferred tax assets, valuation allowance	$ 2,100	$ 2,100

Debt, Net (Details)

Debt, Net (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Debt
Carrying Value	$ 1,903,657,000		$ 1,904,001,000
Deferred financing costs, net	2,444,000		3,128,000
Interest costs capitalized	1,500,000	$ 1,800,000
Secured Debt
Debt
Carrying Value	166,659,000		167,591,000
Loans payable
Debt
Deferred financing costs, net	5,700,000		6,100,000
Fixed rate debt | Secured Debt
Debt
Carrying Value	153,294,000		154,143,000
Unamortized premium included in carrying value	$ 403,000		422,000
Weighted average interest rate (as a percent)	4.19%
Fixed rate debt | Secured Debt | Minimum
Debt
Stated interest rate (as a percent)	3.82%
Fixed rate debt | Secured Debt | Maximum
Debt
Stated interest rate (as a percent)	7.87%
Variable-rate debt
Debt
Description of variable rate basis	LIBOR
Variable-rate debt | Secured Debt
Debt
Carrying Value	$ 13,365,000		13,448,000
Stated interest rate (as a percent)	2.63%
Variable-rate debt | Secured Debt | London Interbank Offered Rate (LIBOR)
Debt
Variable rate, spread (as a percent)	1.85%
Revolving Credit Facility
Debt
Carrying Value	$ 0		0
Description of variable rate basis	LIBOR
Revolving Credit Facility | Minimum | London Interbank Offered Rate (LIBOR)
Debt
Variable rate, spread (as a percent)	0.875%
Revolving Credit Facility | Maximum | London Interbank Offered Rate (LIBOR)
Debt
Variable rate, spread (as a percent)	1.60%
Term Loan Facilities
Debt
Carrying Value	$ 547,682,000		547,494,000
Description of variable rate basis	LIBOR
Weighted average interest rate (as a percent)	2.37%
Aggregate additional borrowing capacity available	$ 350,000,000
Term Loan Facilities | Minimum | London Interbank Offered Rate (LIBOR)
Debt
Variable rate, spread (as a percent)	0.90%
Term Loan Facilities | Maximum | London Interbank Offered Rate (LIBOR)
Debt
Variable rate, spread (as a percent)	2.40%
3.60% Senior Notes | Unsecured senior notes
Debt
Carrying Value	$ 347,233,000		347,128,000
Debt instrument, face amount	$ 350,000,000
Stated interest rate (as a percent)	3.60%
Unamortized discount included in carrying value	$ 1,900,000		2,000,000
Interest rate on debt (as a percent)	3.70%
5.250% Senior Notes | Unsecured senior notes
Debt
Carrying Value	$ 246,291,000		246,176,000
Debt instrument, face amount	$ 250,000,000
Stated interest rate (as a percent)	5.25%
Unamortized discount included in carrying value	$ 3,300,000		3,400,000
Interest rate on debt (as a percent)	5.49%
3.70% Senior Notes | Unsecured senior notes
Debt
Carrying Value	$ 297,961,000		297,843,000
Debt instrument, face amount	$ 300,000,000
Stated interest rate (as a percent)	3.70%
Unamortized discount included in carrying value	$ 1,600,000		1,700,000
Interest rate on debt (as a percent)	3.85%
5.000% Senior Notes | Unsecured senior notes
Debt
Carrying Value	$ 296,457,000		296,368,000
Debt instrument, face amount	$ 300,000,000
Stated interest rate (as a percent)	5.00%
Unamortized discount included in carrying value	$ 2,900,000		3,000,000
Interest rate on debt (as a percent)	5.15%
Unsecured notes payable
Debt
Carrying Value	$ 1,374,000		1,401,000
Stated interest rate (as a percent)	0.00%
Unamortized discount included in carrying value	$ 438,000		$ 460,000

Debt, Net (Details 2)

Debt, Net (Details 2) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Carrying Amount
Carrying amount and estimated fair value of debt
Long-term debt	$ 1,903,657	$ 1,904,001
Carrying Amount | Unsecured senior notes
Carrying amount and estimated fair value of debt
Long-term debt	1,187,942	1,187,515
Carrying Amount | Other fixed-rate debt
Carrying amount and estimated fair value of debt
Long-term debt	154,668	155,544
Carrying Amount | Variable-rate debt
Carrying amount and estimated fair value of debt
Long-term debt	561,047	560,942
Estimated Fair Value
Carrying amount and estimated fair value of debt
Long-term debt	1,936,695	1,935,606
Estimated Fair Value | Unsecured senior notes
Carrying amount and estimated fair value of debt
Long-term debt	1,223,753	1,220,282
Estimated Fair Value | Other fixed-rate debt
Carrying amount and estimated fair value of debt
Long-term debt	156,098	156,887
Estimated Fair Value | Variable-rate debt
Carrying amount and estimated fair value of debt
Long-term debt	$ 556,844	$ 558,437

Interest Rate Derivatives (Deta

Interest Rate Derivatives (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Effect of interest rate derivatives on consolidated statements of operations and comprehensive income
Amount of gain (loss) recognized in accumulated other comprehensive loss (“AOCL”) (effective portion)	$ 224	$ (11,284)
Amount of losses reclassified from AOCL into interest expense (effective portion)	(1,184)	(870)
Interest rate swaps
Effect of interest rate derivatives on consolidated statements of operations and comprehensive income
Approximate loss amount to be reclassified from AOCI to interest expense over the next 12 months	2,600
Interest rate derivatives in liability position, fair value	735
Termination value to settle obligations under interest rate derivative agreements	892
Interest rate swaps | Interest Expense
Effect of interest rate derivatives on consolidated statements of operations and comprehensive income
Amount of gain (loss) recognized in interest expense (ineffective portion)	454	$ (1,551)
Interest rate swaps | Prepaid expenses and other current assets
Fair value of interest rate derivatives and balance sheet classification
Interest rate swaps designated as cash flow hedges	1,183		$ 158
Interest rate swaps | Other Liabilities
Fair value of interest rate derivatives and balance sheet classification
Interest rate swaps designated as cash flow hedges	(735)		(1,572)
Designated
Fair values of interest rate swap derivatives
Fair value of interest rate swaps	448		(1,414)
Designated | Interest rate swap, effective date September 1, 2015, swap one
Fair values of interest rate swap derivatives
Notional Amount	$ 100,000
Fixed rate (as a percent)	1.673%
Fair value of interest rate swaps	$ (301)		(701)
Designated | Interest rate swap, effective date September 1, 2015, swap two
Fair values of interest rate swap derivatives
Notional Amount	$ 100,000
Fixed rate (as a percent)	1.73%
Fair value of interest rate swaps	$ (434)		(848)
Designated | Interest rate swap, effective October 13, 2015
Fair values of interest rate swap derivatives
Notional Amount	$ 13,494
Fixed rate (as a percent)	1.39%
Fair value of interest rate swaps	$ 147		100
Notional amount of interest rate derivatives after scheduled amortization	12,100
Designated | Interest rate swap, effective September 1, 2016, swap one
Fair values of interest rate swap derivatives
Notional Amount	$ 100,000
Fixed rate (as a percent)	1.9013%
Fair value of interest rate swaps	$ 409		(23)
Designated | Interest rate swap, effective September 1, 2016, swap two
Fair values of interest rate swap derivatives
Notional Amount	$ 100,000
Fixed rate (as a percent)	1.905%
Fair value of interest rate swaps	$ 427		48
Designated | Interest rate swap, effective September 1, 2016, swap three
Fair values of interest rate swap derivatives
Notional Amount	$ 50,000
Fixed rate (as a percent)	1.9079%
Fair value of interest rate swaps	$ 200		$ 10

Redeemable Noncontrolling Int54

Redeemable Noncontrolling Interests (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017USD ($)joint_venture	Mar. 31, 2016USD ($)
Noncontrolling Interest [Abstract]
Number of joint ventures with redeemable noncontrolling interests | joint_venture	2
Redeemable Noncontrolling Interest [Roll Forward]
Beginning balance	$ 22,979	$ 19,218
Contributions from noncontrolling interests	0	22,779
Distributions to noncontrolling interests	(415)	(20,526)
Net income attributable to noncontrolling interests	567	560
Adjustment to arrive at fair value of interests	545	302
Ending balance	$ 23,676	$ 22,333

Equity (Details)

Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	Jan. 21, 2017	Mar. 31, 2017	Dec. 31, 2016
Class of Stock [Line Items]
Conversion of common units to common shares (in units/ shares)		185,000
Common Stock Issued to Public Under At-the-Market Program
Class of Stock [Line Items]
Shares issued to the public		546,782
Issuance of stock, weighted average price per share (in dollars per share)		$ 33.89
Net proceeds from shares issued		$ 18,300
Payments of stock issuance costs		278
At-market stock, offering program established, remaining capacity		$ 71,500
Redeemable Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock, redemption price per share (in dollars per share)	$ 50
Stock redeemed or called during period value	$ 26,600
Issuance costs associated with redeemed preferred shares			$ 17

Information by Business Segme56

Information by Business Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Segment financial information for real estate operations
Revenues from real estate operations	$ 126,767	$ 133,087
Property operating expenses	(48,519)	(51,875)
UJV NOI allocable to COPT	1,298	0
NOI from real estate operations	79,546	81,212
Additions to long-lived assets	17,040	14,401
Transfers from non-operating properties	12,645	62,093
Segment assets	3,739,366	3,937,908	$ 3,780,885
Defense/Information Technology Locations
Segment financial information for real estate operations
Revenues from real estate operations	100,188	101,230
Property operating expenses	(37,013)	(38,519)
UJV NOI allocable to COPT	1,298
NOI from real estate operations	64,473	62,711
Additions to long-lived assets	8,190	11,485
Transfers from non-operating properties	12,619	61,971
Segment assets	2,262,632	2,391,207
Defense/Information Technology Locations | Fort Meade/BW Corridor
Segment financial information for real estate operations
Revenues from real estate operations	60,855	62,509
Property operating expenses	(20,520)	(23,246)
UJV NOI allocable to COPT	0
NOI from real estate operations	40,335	39,263
Additions to long-lived assets	3,422	6,519
Transfers from non-operating properties	13,416	35,751
Segment assets	1,258,437	1,319,444
Defense/Information Technology Locations | Northern Virginia Defense/IT
Segment financial information for real estate operations
Revenues from real estate operations	11,707	12,116
Property operating expenses	(4,452)	(4,541)
UJV NOI allocable to COPT	0
NOI from real estate operations	7,255	7,575
Additions to long-lived assets	2,468	3,078
Transfers from non-operating properties	222	(94)
Segment assets	361,449	407,199
Defense/Information Technology Locations | Lackland Air Force Base
Segment financial information for real estate operations
Revenues from real estate operations	11,634	10,225
Property operating expenses	(6,802)	(5,420)
UJV NOI allocable to COPT	0
NOI from real estate operations	4,832	4,805
Additions to long-lived assets	0	0
Transfers from non-operating properties	0	6
Segment assets	131,194	133,757
Defense/Information Technology Locations | Navy Support Locations
Segment financial information for real estate operations
Revenues from real estate operations	7,010	6,934
Property operating expenses	(3,209)	(3,524)
UJV NOI allocable to COPT	0
NOI from real estate operations	3,801	3,410
Additions to long-lived assets	2,168	1,270
Transfers from non-operating properties	0	0
Segment assets	195,892	195,306
Defense/Information Technology Locations | Redstone Arsenal
Segment financial information for real estate operations
Revenues from real estate operations	3,460	3,116
Property operating expenses	(1,371)	(978)
UJV NOI allocable to COPT	0
NOI from real estate operations	2,089	2,138
Additions to long-lived assets	132	618
Transfers from non-operating properties	(4)	211
Segment assets	109,171	107,693
Defense/Information Technology Locations | Data Center Shells
Segment financial information for real estate operations
Revenues from real estate operations	5,522	6,330
Property operating expenses	(659)	(810)
UJV NOI allocable to COPT	1,298
NOI from real estate operations	6,161	5,520
Additions to long-lived assets	0	0
Transfers from non-operating properties	(1,015)	26,097
Segment assets	206,489	227,808
Regional Office
Segment financial information for real estate operations
Revenues from real estate operations	18,276	23,502
Property operating expenses	(7,486)	(9,831)
UJV NOI allocable to COPT	0
NOI from real estate operations	10,790	13,671
Additions to long-lived assets	7,120	2,759
Transfers from non-operating properties	0	82
Segment assets	439,079	603,662
Operating wholesale data centers
Segment financial information for real estate operations
Revenues from real estate operations	6,770	6,493
Property operating expenses	(3,365)	(2,661)
UJV NOI allocable to COPT	0
NOI from real estate operations	3,405	3,832
Additions to long-lived assets	1,574	0
Transfers from non-operating properties	8	51
Segment assets	229,630	240,484
Other Segments
Segment financial information for real estate operations
Revenues from real estate operations	1,533	1,862
Property operating expenses	(655)	(864)
UJV NOI allocable to COPT	0
NOI from real estate operations	878	998
Additions to long-lived assets	156	157
Transfers from non-operating properties	18	(11)
Segment assets	21,011	70,039
Segment assets
Segment financial information for real estate operations
Segment assets	$ 2,952,352	$ 3,305,392

Information by Business Segme57

Information by Business Segment (Details 2) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Reconciliation of segment revenues to total revenues
Segment revenues from real estate operations	$ 126,767	$ 133,087
Construction contract and other service revenues	13,034	11,220
Total revenues	139,801	144,307
Reconciliation of UJV NOI allocable to COPT to Equity Income in Unconsolidated Entities
UJV NOI allocable to COPT	1,298	0
Less: Income from UJV allocable to COPT attributable to depreciation and amortization expense and interest expense	(572)	0
Add: Equity in (loss) income of unconsolidated non-real estate entities	(1)	10
Equity in income of unconsolidated entities	725	10
Computation of net operating income from service operations
Construction contract and other service revenues	13,034	11,220
Construction contract and other service expenses	(12,486)	(10,694)
NOI from service operations	$ 548	$ 526

Information by Business Segme58

Information by Business Segment (Details 3) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Reconciliation of NOI from real estate operations and NOI from service operations to (loss) income from continuing operations
NOI from real estate operations	$ 79,546	$ 81,212
NOI from service operations	548	526
Interest and other income	1,726	1,156
Equity in income of unconsolidated entities	725	10
Income tax (expense) benefit	(40)	8
Depreciation and other amortization associated with real estate operations	(33,059)	(34,527)
Impairment losses	0	(2,446)
General, administrative and leasing expenses	(8,611)	(11,883)
Business development expenses and land carry costs	(1,693)	(2,418)
Interest expense	(18,994)	(23,559)
Less: UJV NOI allocable to COPT included in equity in income of unconsolidated entities	(1,298)	0
Gain on early extinguishment of debt	0	17
Income before gain on sales of real estate	$ 18,850	$ 8,096

Information by Business Segme59

Information by Business Segment (Details 4) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Reconciliation of segment assets to total assets
Assets	$ 3,739,366	$ 3,780,885	$ 3,937,908
Segment assets
Reconciliation of segment assets to total assets
Assets	2,952,352		3,305,392
Non-operating property assets
Reconciliation of segment assets to total assets
Assets	429,690		444,334
Other assets
Reconciliation of segment assets to total assets
Assets	$ 357,324		$ 188,182

Share-Based Compensation and 60

Share-Based Compensation and Other Compensation Matters (Details) $ / shares in Units, $ in Millions	Feb. 07, 2017shares	Jan. 01, 2017USD ($)Percentile_Rank$ / sharesshares	Mar. 31, 2017USD ($)$ / sharesshares
Restricted shares
Share-Based Compensation
Stock awards granted (in shares or units) | shares			208,953
Aggregate grant date fair value | $			$ 7.1
Assumptions used to value stock awards
Weighted average grant date fair value (in dollars per share) | $ / shares			$ 34.02
Other Share-based Compensation Additional Disclosures
Shares vested (in shares) | shares			139,201
Weighted average fair value of shares vested (in dollars per share) | $ / shares			$ 26.21
Aggregate intrinsic value of awards upon vesting | $			$ 4.7
2017 PSU Grants | Performance share units
Share-Based Compensation
Stock awards granted (in shares or units) | shares		36,525
Aggregate grant date fair value | $		$ 1.4
Potential earned PSUs payout for defined levels of performance under awards
Earned PSUs payout (as a percent of PSUs granted) on 75th or greater percentile rank		200.00%
Earned PSUs payout (as a percent of PSUs granted) on 50th percentile rank		100.00%
Earned PSUs payout (as a percent of PSUs granted) on 25th percentile rank		50.00%
Performance share units granted on percentile rank below 25th (as a percent)		0.00%
The number of percentile ranks to fall between to earn interpolated PSUs between such percentile ranks, conditioned on the percentile rank exceeding 25% | Percentile_Rank		2
Assumptions used to value stock awards
Performance period of the award		3 years
Weighted average grant date fair value (in dollars per share) | $ / shares		$ 38.43
Baseline value per common share (in dollars per share) | $ / shares		$ 31.22
Expected volatility of common shares (as a percent)		19.00%
Risk-free interest rate (as a percent)		1.47%
2014 PSU Grants | Performance share units | Chief Executive Officer
Other Share-based Compensation Additional Disclosures
Shares issued (in shares) | shares	9,763
Percentage of target	100.00%

Earnings Per Share ("EPS") an61

Earnings Per Share ("EPS") and Earnings Per Unit ("EPU") (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Numerator:
Net income attributable to COPT	$ 21,355	$ 6,826
Preferred share/unit dividends/distributions	(3,180)	(3,552)
Income attributable to share-based compensation awards	(125)	(118)
Numerator for basic and diluted EPS on net income attributable to COPT common shareholders	$ 18,050	$ 3,156
Denominator (all weighted averages):
Denominator for basic EPS (common shares)	98,411	94,203
Dilutive effect of share-based compensation awards (shares)	155	95
Denominator for diluted EPS (common shares)	98,566	94,298
Basic EPS:
Net income (loss) attributable to COPT common shareholders - basic (in dollars per share/unit)	$ 0.18	$ 0.03
Diluted EPS:
Net income (loss) attributable to COPT common shareholders - diluted (in dollars per share/unit)	$ 0.18	$ 0.03
Corporate Office Properties, L.P.
Numerator:
Net income attributable to COPT	$ 22,154	$ 7,117
Preferred share/unit dividends/distributions	(3,345)	(3,717)
Income attributable to share-based compensation awards	(125)	(118)
Numerator for basic and diluted EPS on net income attributable to COPT common shareholders	$ 18,684	$ 3,282
Denominator (all weighted averages):
Denominator for basic EPS (common shares)	101,857	97,880
Dilutive effect of share-based compensation awards (shares)	155	95
Denominator for diluted EPS (common shares)	102,012	97,975
Basic EPS:
Net income (loss) attributable to COPT common shareholders - basic (in dollars per share/unit)	$ 0.18	$ 0.03
Diluted EPS:
Net income (loss) attributable to COPT common shareholders - diluted (in dollars per share/unit)	$ 0.18	$ 0.03

Earnings Per Share ("EPS") an62

Earnings Per Share ("EPS") and Earnings Per Unit ("EPU") (Details 2) - shares	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Conversion of common units
Antidilutive securities
Antidilutive securities excluded from computation of diluted earnings per share (in shares)	3,446,000	3,677,000
Conversion of Series I Preferred Units
Antidilutive securities
Antidilutive securities excluded from computation of diluted earnings per share (in shares)	176,000	176,000
Conversion of Series K Preferred Shares
Antidilutive securities
Antidilutive securities excluded from computation of diluted earnings per share (in shares)	0	434,000
Weighted average restricted stock and deferred shares
Antidilutive securities
Antidilutive securities excluded from computation of diluted earnings per share (in shares)	392,000	405,000
Weighted average options
Antidilutive securities
Antidilutive securities excluded from computation of diluted earnings per share (in shares)	140,000	379,000
Corporate Office Properties, L.P. | Conversion of Series I Preferred Units
Antidilutive securities
Antidilutive securities excluded from computation of diluted earnings per share (in shares)	176,000	176,000
Corporate Office Properties, L.P. | Weighted average restricted stock and deferred shares
Antidilutive securities
Antidilutive securities excluded from computation of diluted earnings per share (in shares)	392,000	405,000
Corporate Office Properties, L.P. | Weighted average options
Antidilutive securities
Antidilutive securities excluded from computation of diluted earnings per share (in shares)	140,000	379,000
Corporate Office Properties, L.P. | Conversion of Series K preferred units
Antidilutive securities
Antidilutive securities excluded from computation of diluted earnings per share (in shares)	0	434,000

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details)	Mar. 31, 2017USD ($)Property	Aug. 31, 2010USD ($)
Environmental Indemnity Agreement
Number of properties which were provided environmental indemnifications | Property	3
Maximum additional costs agreed to be paid by the entity under environmental indemnification agreement	$ 19,000,000
New Development and Redevelopment Obligations
Tax incremental financing obligation
Purchase obligations	128,000,000
Capital Expenditures For Operating Properties
Tax incremental financing obligation
Purchase obligations	51,800,000
Third Party Construction and Development
Tax incremental financing obligation
Purchase obligations	6,700,000
Other Obligations
Tax incremental financing obligation
Purchase obligations	1,400,000
Specialty Tax Guarantee
Tax incremental financing obligation
Liability recognized with regard to tax incremental financing obligation at end of current period	$ 1,500,000
Specialty Tax Guarantee | Anne Arundel County, Maryland | Tax Incremental Financing Bond
Loss Contingencies [Line Items]
Loan amount		$ 30,000,000

Commitments and Contingencies64

Commitments and Contingencies - Future Minimum Payments (Details) $ in Thousands	Mar. 31, 2017USD ($)
Commitments and Contingencies Disclosure [Abstract]
2,017	$ 985
2,018	1,290
2,019	1,269
2,020	1,261
2,021	1,260
Thereafter	85,762
Total	$ 91,827