Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 43,898	$ 25,121	$ 37,819	$ 50,671
Other comprehensive income (loss):
Unrealized (loss) income on interest rate derivatives	(240)	(3,315)	544	(41,020)
Reclassification adjustments on interest rate derivatives recognized in interest expense	1,203	935	2,378	1,066
Total other comprehensive income (loss)	963	(2,380)	2,922	(39,954)
Comprehensive income	44,861	22,741	40,741	10,717
Comprehensive income attributable to noncontrolling interests	(1,484)	(1,556)	(2,267)	(2,235)
Comprehensive income attributable to COPT	$ 43,377	$ 21,185	$ 38,474	$ 8,482