Consolidated Statements of Changes in Shareholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Revision of Prior Period, Accounting Standards Update, Adjustment	Common Stock	Treasury Stock	Additional Paid-in Capital	Additional Paid-in Capital Revision of Prior Period, Accounting Standards Update, Adjustment	Retained Earnings (Accumulated Deficit)	Retained Earnings (Accumulated Deficit) Revision of Prior Period, Accounting Standards Update, Adjustment	Accumulated Other Comprehensive (Loss) Income	Total Parsons Equity	Total Parsons Equity Revision of Prior Period, Accounting Standards Update, Adjustment	Noncontrolling Interests
Beginning balance at Dec. 31, 2020	$ 1,861,417		$ 146,609	$ (899,328)	$ 2,700,925		$ (120,569)		$ (13,865)	$ 1,813,772		$ 47,645
Beginning balance (ASC 2020-06) at Dec. 31, 2020		$ (37,220)				$ (40,002)		$ 2,782			$ (37,220)
Comprehensive income
Net income	88,952						64,072			64,072		24,880
Foreign currency translation gain (loss), net	3,834								3,837	3,837		(3)
Pension adjustments, net	460								460	460
Contributions of treasury stock to ESOP	54,001			31,937	22,064					54,001
Contributions	1,754											1,754
Distributions	(37,932)											(37,932)
Issuance of equity securities, net of retirements	3,360		287		2,887		186			3,360
Repurchases of common stock	(21,701)		(619)		(21,082)					(21,701)
Stock-based compensation	20,187				20,187					20,187
Ending Balance at Dec. 31, 2021	1,937,112		146,277	(867,391)	2,684,979		(53,529)		(9,568)	1,900,768		36,344
Comprehensive income
Net income	126,565						96,664			96,664		29,901
Foreign currency translation gain (loss), net	(7,752)								(7,734)	(7,734)		(18)
Pension adjustments, net	(547)								(547)	(547)
Contributions of treasury stock to ESOP	53,801			22,455	31,346					53,801
Contributions	10,266											10,266
Distributions	(24,128)											(24,128)
Issuance of equity securities, net of retirements	(390)		429		(773)		(46)			(390)
Repurchases of common stock	(22,000)		(574)		(21,426)					(22,000)
Stock-based compensation	23,008				23,008					23,008
Ending Balance at Dec. 31, 2022	2,095,935		146,132	(844,936)	2,717,134		43,089		(17,849)	2,043,570		52,365
Comprehensive income
Net income	207,915						161,149			161,149		46,766
Foreign currency translation gain (loss), net	2,375								2,373	2,373		2
Pension adjustments, net	568								568	568
Contributions of treasury stock to ESOP	57,429			17,625	39,804					57,429
Contributions	2,867											2,867
Distributions	(12,496)											(12,496)
Issuance of equity securities, net of retirements	(1,243)		442		(1,171)		(514)			(1,243)
Repurchases of common stock	(11,000)		(233)		(10,767)					(11,000)
Stock-based compensation	34,365				34,365					34,365
Ending Balance at Dec. 31, 2023	$ 2,376,715		$ 146,341	$ (827,311)	$ 2,779,365		$ 203,724		$ (14,908)	$ 2,287,211		$ 89,504