Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities
Revenues from real estate operations received	$ 255,302	$ 261,980
Construction contract and other service revenues received	39,917	34,992
Property operating expenses paid	(80,385)	(87,005)
Construction contract and other service expenses paid	(31,996)	(24,303)
General, administrative, leasing, business development and land carry costs paid	(20,315)	(19,212)
Interest expense paid	(36,351)	(41,179)
Lease incentives	(9,375)	(996)
Other	940	123
Net cash provided by operating activities	117,737	124,400
Cash flows from investing activities
Construction, development and redevelopment	(85,926)	(75,339)
Tenant improvements on operating properties	(13,711)	(14,862)
Other capital improvements on operating properties	(11,780)	(16,007)
Proceeds from dispositions of properties	54,798	5,448
Leasing costs paid	(3,904)	(3,434)
Other	1,573	(13)
Net cash used in investing activities	(58,950)	(104,207)
Proceeds from debt
Revolving Credit Facility	213,000	133,500
Other debt proceeds	0	45,000
Repayments of debt
Revolving Credit Facility	(19,000)	(119,000)
Scheduled principal amortization	(1,913)	(3,532)
Other debt repayments	(200,100)	(40,498)
Net proceeds from issuance of common shares/units	19,835	(5)
Redemption of preferred shares/units	(199,083)	0
Common share/unit dividends/distributions paid	(54,439)	(52,021)
Preferred share/unit dividends/distributions paid	(9,305)	(7,105)
Distributions paid to noncontrolling interests in COPLP	(2,274)	(2,362)
Distributions paid to redeemable noncontrolling interests	(781)	(14,306)
Redemption of vested equity awards	(1,813)	(1,492)
Other	(2,171)	(5,365)
Net cash used in financing activities	(258,044)	(67,186)
Net decrease in cash and cash equivalents	(199,257)	(46,993)
Cash and cash equivalents
Beginning of period	209,863	60,310
End of period	10,606	13,317
Reconciliation of net income (loss) to net cash provided by operating activities:
Net income (loss)	42,295	(40,220)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	66,948	68,901
Impairment losses	1,618	72,138
(Gain) loss on interest rate derivatives	(9)	1,870
Amortization of deferred financing costs and net debt discounts	2,613	2,998
Decrease (increase) in deferred rent receivable	669	(1,276)
Gain on sales of real estate	(4,250)	0
Share-based compensation	2,820	3,839
Other	(2,548)	(1,725)
Operating changes in assets and liabilities:
Increase in accounts receivable	(8,304)	(3,320)
Decrease (increase) in restricted cash and marketable securities	1,826	(389)
Decrease in prepaid expenses and other assets, net	20,800	11,303
(Decrease) increase in accounts payable, accrued expenses and other liabilities	(2,387)	15,394
Decrease in rents received in advance and security deposits	(4,354)	(5,113)
Net cash provided by operating activities	117,737	124,400
Supplemental schedule of non-cash investing and financing activities:
(Decrease) increase in accrued capital improvements, leasing and other investing activity costs	(4,927)	1,604
Increase in property in connection with capital lease obligation	16,127	0
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	0	6,675
Increase (decrease) in fair value of derivatives applied to accumulated other comprehensive loss and noncontrolling interests	513	(15,268)
Equity in other comprehensive income (loss) of an equity method investee	39	(184)
Dividends/distributions payable	28,462	30,219
Decrease in noncontrolling interests and increase in shareholders’ equity in connection with the conversion of common units into common shares	2,564	371
Adjustments to noncontrolling interests resulting from changes in COPLP ownership	514	5
Increase in redeemable noncontrolling interest and decrease in equity to carry redeemable noncontrolling interest at fair value	401	349
Corporate Office Properties, L.P.
Cash flows from operating activities
Revenues from real estate operations received	255,302	261,980
Construction contract and other service revenues received	39,917	34,992
Property operating expenses paid	(80,385)	(87,005)
Construction contract and other service expenses paid	(31,996)	(24,303)
General, administrative, leasing, business development and land carry costs paid	(20,315)	(19,212)
Interest expense paid	(36,351)	(41,179)
Lease incentives	(9,375)	(996)
Other	940	123
Net cash provided by operating activities	117,737	124,400
Cash flows from investing activities
Construction, development and redevelopment	(85,926)	(75,339)
Tenant improvements on operating properties	(13,711)	(14,862)
Other capital improvements on operating properties	(11,780)	(16,007)
Proceeds from dispositions of properties	54,798	5,448
Leasing costs paid	(3,904)	(3,434)
Other	1,573	(13)
Net cash used in investing activities	(58,950)	(104,207)
Proceeds from debt
Revolving Credit Facility	213,000	133,500
Other debt proceeds	0	45,000
Repayments of debt
Revolving Credit Facility	(19,000)	(119,000)
Scheduled principal amortization	(1,913)	(3,532)
Other debt repayments	(200,100)	(40,498)
Net proceeds from issuance of common shares/units	19,835	(5)
Redemption of preferred shares/units	(199,083)	0
Common share/unit dividends/distributions paid	(56,383)	(54,053)
Preferred share/unit dividends/distributions paid	(9,635)	(7,435)
Distributions paid to redeemable noncontrolling interests	(781)	(14,306)
Redemption of vested equity awards	(1,813)	(1,492)
Other	(2,171)	(5,365)
Net cash used in financing activities	(258,044)	(67,186)
Net decrease in cash and cash equivalents	(199,257)	(46,993)
Cash and cash equivalents
Beginning of period	209,863	60,310
End of period	10,606	13,317
Reconciliation of net income (loss) to net cash provided by operating activities:
Net income (loss)	42,295	(40,220)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	66,948	68,901
Impairment losses	1,618	72,138
(Gain) loss on interest rate derivatives	(9)	1,870
Amortization of deferred financing costs and net debt discounts	2,613	2,998
Decrease (increase) in deferred rent receivable	669	(1,276)
Gain on sales of real estate	(4,250)	0
Share-based compensation	2,820	3,839
Other	(2,548)	(1,725)
Operating changes in assets and liabilities:
Increase in accounts receivable	(8,304)	(3,320)
Decrease (increase) in restricted cash and marketable securities	534	(1,106)
Decrease in prepaid expenses and other assets, net	20,800	11,303
(Decrease) increase in accounts payable, accrued expenses and other liabilities	(1,095)	16,111
Decrease in rents received in advance and security deposits	(4,354)	(5,113)
Net cash provided by operating activities	117,737	124,400
Supplemental schedule of non-cash investing and financing activities:
(Decrease) increase in accrued capital improvements, leasing and other investing activity costs	(4,927)	1,604
Increase in property in connection with capital lease obligation	16,127	0
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	0	6,675
Increase (decrease) in fair value of derivatives applied to accumulated other comprehensive loss and noncontrolling interests	513	(15,268)
Equity in other comprehensive income (loss) of an equity method investee	39	(184)
Dividends/distributions payable	28,462	30,219
Increase in redeemable noncontrolling interest and decrease in equity to carry redeemable noncontrolling interest at fair value	$ 401	$ 349