Revenue Recognition (Tables)

9 Months Ended

Sep. 30, 2022

Revenue From Contract With Customer [Abstract]

Disaggregation of Revenue

	Three Months Ended September 30,										Nine Months Ended September 30,
	2022					2021					2022					2021
	Dollars		Percent			Dollars		Percent			Dollars		Percent			Dollars		Percent
Client Markets:
Energy, environment, and infrastructure	$	166,956		36	%	$	156,384		40	%	$	483,415		37	%	$	486,945		42	%
Health, education, and social programs		249,034		53	%		182,292		46	%		663,739		51	%		508,161		43	%
Safety and security		33,760		7	%		28,311		7	%		96,568		7	%		89,130		8	%
Consumer and financial		18,027		4	%		27,073		7	%		60,633		5	%		80,827		7	%
Total	$	467,777		100	%	$	394,060		100	%	$	1,304,355		100	%	$	1,165,063		100	%

	Three Months Ended September 30,										Nine Months Ended September 30,
	2022					2021					2022					2021
	Dollars		Percent			Dollars		Percent			Dollars		Percent			Dollars		Percent
Client Type:
U.S. federal government	$	271,255		58	%	$	195,153		50	%	$	714,993		55	%	$	553,378		48	%
U.S. state and local government		65,613		14	%		58,792		15	%		195,791		15	%		174,446		15	%
International government		23,075		5	%		32,697		8	%		78,978		6	%		107,850		9	%
Total Government		359,943		77	%		286,642		73	%		989,762		76	%		835,674		72	%
Commercial		107,834		23	%		107,418		27	%		314,593		24	%		329,389		28	%
Total	$	467,777		100	%	$	394,060		100	%	$	1,304,355		100	%	$	1,165,063		100	%

	Three Months Ended September 30,										Nine Months Ended September 30,
	2022					2021					2022					2021
	Dollars		Percent			Dollars		Percent			Dollars		Percent			Dollars		Percent
Contract Mix:
Time-and-materials	$	188,758		40	%	$	157,627		40	%	$	523,635		40	%	$	479,712		41	%
Fixed price		210,810		45	%		166,053		42	%		580,738		45	%		473,810		41	%
Cost-based		68,209		15	%		70,380		18	%		199,982		15	%		211,541		18	%
Total	$	467,777		100	%	$	394,060		100	%	$	1,304,355		100	%	$	1,165,063		100	%

Schedule of Contract Balances and Changes in Contract Balances

Contract Balances:

Contract assets consist primarily of unbilled amounts resulting from long-term contracts when revenue recognized exceeds the amount billed often due to billing schedule timing. Contract liabilities result from advance payments received on a contract or from billings in excess of revenue recognized on long-term contracts due to billing schedule timing.

The following table summarizes the contract balances as of September 30, 2022 and December 31, 2021:

	September 30, 2022			December 31, 2021			$ Change		% Change
Contract assets	$	196,811		$	137,867		$	58,944		42.8	%
Contract liabilities		(24,599	)		(39,665	)		15,066		(38.0	%)
Net contract assets (liabilities)	$	172,212		$	98,202		$	74,010		75.4	%