Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement Of Income And Comprehensive Income [Abstract]
Net income including noncontrolling interests	$ 12,027	$ 31,125	$ 26,041	$ 45,496
Other comprehensive income (loss), net of tax
Foreign currency translation adjustment, net of tax	3,012	3,104	7,926	(5,696)
Pension adjustments, net of tax	19	23	38	(38)
Comprehensive income including noncontrolling interests, net of tax	15,058	34,252	34,005	39,762
Comprehensive income attributable to noncontrolling interests, net of tax	(5,324)	(7,830)	(10,304)	(9,220)
Comprehensive income attributable to Parsons Corporation, net of tax	$ 9,734	$ 26,422	$ 23,701	$ 30,542