Revenue Recognition (Tables)

9 Months Ended

Sep. 30, 2020

Revenue From Contract With Customer [Abstract]

Changes in the three and nine months ended September 30, 2020 compared to the prior year period were primarily from the increase of revenue in the health, education, and social programs client market as a result of additional work performed for U.S. government clients, including the ITG acquisition, offset by decreases in revenue from the commercial clients primarily in the consumer and financial services, and decreases in the U.S. state and local clients in the energy, environment, and infrastructure client markets. Similarly, for the three and nine months ended September 30, 2020 revenue from time-and-materials and fixed price contracts decreased while revenue from cost-based contracts increased compared to the prior year period.

	Three Months Ended September 30,										Nine Months Ended September 30,
	2020					2019					2020					2019
	Dollars		Percent			Dollars		Percent			Dollars		Percent			Dollars		Percent
Client Markets:
Energy, environment, and infrastructure	$	148,286		41	%	$	170,640		46	%	$	451,404		42	%	$	485,925		45	%
Health, education, and social programs		159,508		44	%		143,433		38	%		457,553		43	%		408,712		38	%
Safety and security		29,281		8	%		29,416		8	%		89,978		8	%		88,249		8	%
Consumer and financial services		23,240		7	%		30,429		8	%		73,605		7	%		99,003		9	%
Total	$	360,315		100	%	$	373,918		100	%	$	1,072,540		100	%	$	1,081,889		100	%

	Three Months Ended September 30,										Nine Months Ended September 30,
	2020					2019					2020					2019
	Dollars		Percent			Dollars		Percent			Dollars		Percent			Dollars		Percent
Client Type:
U.S. federal government	$	175,093		49	%	$	148,339		40	%	$	501,496		47	%	$	421,696		39	%
U.S. state and local government		51,589		14	%		71,505		19	%		170,617		16	%		209,993		19	%
International government		20,299		6	%		28,003		7	%		61,421		6	%		86,839		8	%
Total Government		246,981		69	%		247,847		66	%		733,534		69	%		718,528		66	%
Commercial		113,334		31	%		126,071		34	%		339,006		31	%		363,361		34	%
Total	$	360,315		100	%	$	373,918		100	%	$	1,072,540		100	%	$	1,081,889		100	%

	Three Months Ended September 30,										Nine Months Ended September 30,
	2020					2019					2020					2019
	Dollars		Percent			Dollars		Percent			Dollars		Percent			Dollars		Percent
Contract Mix:
Time-and-materials	$	168,458		47	%	$	183,872		49	%	$	505,185		47	%	$	506,183		47	%
Fixed price		134,980		37	%		135,720		36	%		391,888		37	%		417,016		38	%
Cost-based		56,877		16	%		54,326		15	%		175,467		16	%		158,690		15	%
Total	$	360,315		100	%	$	373,918		100	%	$	1,072,540		100	%	$	1,081,889		100	%

Schedule of Contract Balances and Changes in Contract Balances

Contract Balances:

	September 30, 2020			December 31, 2019			$ Change			% Change
Contract assets	$	139,860		$	142,337		$	(2,477	)		-1.7	%
Contract liabilities		(36,473	)		(37,413	)		940			(2.5	%)
Net contract assets (liabilities)	$	103,387		$	104,924		$	(1,537	)		-1.5	%