Revenue Recognition (Tables)

6 Months Ended

Jun. 30, 2023

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue

	Three Months Ended June 30,										Six Months Ended June 30,
	2023					2022					2023					2022
	Dollars		Percent			Dollars		Percent			Dollars		Percent			Dollars		Percent
Client Markets:
Energy, environment, infrastructure, and disaster recovery	$	202,723		41	%	$	172,103		41	%	$	389,254		40	%	$	343,025		41	%
Health and social programs		207,224		41	%		159,165		37	%		411,463		42	%		314,964		38	%
Security and other civilian & commercial		90,138		18	%		91,842		22	%		182,650		18	%		178,589		21	%
Total	$	500,085		100	%	$	423,110		100	%	$	983,367		100	%	$	836,578		100	%

	Three Months Ended June 30,										Six Months Ended June 30,
	2023					2022					2023					2022
	Dollars		Percent			Dollars		Percent			Dollars		Percent			Dollars		Percent
Client Type:
U.S. federal government	$	271,817		55	%	$	225,298		53	%	$	539,578		55	%	$	444,341		53	%
U.S. state and local government		81,206		16	%		63,704		15	%		156,236		16	%		129,768		15	%
International government		26,322		5	%		28,616		7	%		46,995		5	%		55,994		7	%
Total Government		379,345		76	%		317,618		75	%		742,809		76	%		630,103		75	%
Commercial		120,740		24	%		105,492		25	%		240,558		24	%		206,475		25	%
Total	$	500,085		100	%	$	423,110		100	%	$	983,367		100	%	$	836,578		100	%

	Three Months Ended June 30,										Six Months Ended June 30,
	2023					2022					2023					2022
	Dollars		Percent			Dollars		Percent			Dollars		Percent			Dollars		Percent
Contract Mix:
Time-and-materials	$	208,417		42	%	$	169,923		40	%	$	409,368		42	%	$	334,890		40	%
Fixed-price		225,396		45	%		185,902		44	%		444,383		45	%		369,915		44	%
Cost-based		66,272		13	%		67,285		16	%		129,616		13	%		131,773		16	%
Total	$	500,085		100	%	$	423,110		100	%	$	983,367		100	%	$	836,578		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 June 30, 2023 and December 31, 2022:

	June 30, 2023			December 31, 2022
Contract assets	$	200,202		$	169,088
Contract liabilities		(19,647	)		(25,773	)
Net contract assets (liabilities)	$	180,555		$	143,315