Information by Business Segment - NOI Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment financial information for real estate operations
Depreciation and other amortization associated with real estate operations	$ (148,950)	$ (141,230)	$ (137,543)
Impairment losses	(252,797)	0	0
General, administrative, leasing and other expenses	(42,769)	(38,991)	(40,774)
Interest expense	(71,142)	(61,174)	(65,398)
Interest and other income, net	12,587	9,070	9,007
Gain on sales of real estate	49,392	19,250	65,590
Loss on early extinguishment of debt	0	(609)	(100,626)
Equity in (loss) income of unconsolidated entities	(261)	1,743	1,093
UJV NOI allocable to COPT Defense included in equity in (loss) income of unconsolidated entities	(6,659)	(4,327)	(4,029)
Income tax expense	(588)	(447)	(145)
Revenues from real estate operations from discontinued operations (Note 4)	0	(1,980)	(30,490)
Property operating expenses from discontinued operations (Note 4)	0	971	16,842
(Loss) income from continuing operations	(74,347)	149,249	78,220
Real estate operations
Segment financial information for real estate operations
NOI from real estate operations	384,077	362,304	360,870
UJV NOI allocable to COPT Defense included in equity in (loss) income of unconsolidated entities	(6,659)	(4,327)	(4,029)
Property operating expenses from discontinued operations (Note 4)	0	971	16,842
Service operations
Segment financial information for real estate operations
NOI from service operations	$ 2,763	$ 4,669	$ 3,823