Quarterly Financial Data (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021		Dec. 31, 2020		Dec. 31, 2019
Selected Quarterly Financial Information [Abstract]
Revenue	$ 983,712	$ 875,449	$ 899,203	$ 915,197	$ 1,028,417	$ 891,898	$ 837,492	$ 796,268	$ 3,673,561		$ 3,554,075		$ 3,205,125
Cost of revenue	712,039	601,582	610,307	627,635	727,995	608,242	565,532	502,891	2,551,563		2,404,660
Operating expenses	270,202	266,897	263,105	329,209	282,973	272,380	255,477	521,954	1,129,413		1,332,784
(Loss) income from continuing operations before income taxes	1,471	6,970	25,791	(41,647)	17,449	11,276	16,483	(228,577)	(7,415)		(183,369)		26,732
(Benefit) provision for income taxes	(320)	(1,525)	4,915	(13,992)	(350)	541	16,957	(10,026)	(10,922)		7,122		(13,127)
(Loss) income from continuing operations	1,791	8,495	20,876	(27,655)	17,799	10,735	(474)	(218,551)	3,507		(190,491)
(Loss) income from discontinued operations, net of tax	(524)	572	(1,020)	(3,886)	2,467	616	(3,032)	10,064	(4,858)		10,115		154,460
Net (loss) income	$ 1,267	$ 9,067	$ 19,856	$ (31,541)	$ 20,266	$ 11,351	$ (3,506)	$ (208,487)	$ (1,351)		$ (180,376)		$ 194,319
Basic (loss) earnings per share:
Continuing operations (in dollars per share)	$ 0.01	$ 0.05	$ 0.12	$ (0.16)	$ 0.10	$ 0.06	$ 0	$ (1.28)	$ 0.02	[1]	$ (1.11)	[1]	$ 0.23	[1]
Discontinued operations (in dollars per share)	0	0	(0.01)	(0.02)	0.01	0	(0.02)	0.06	(0.03)	[1]	0.06	[1]	0.88	[1]
Net income (in dollars per share)	0.01	0.05	0.11	(0.18)	0.12	0.07	(0.02)	(1.22)	(0.01)	[1]	(1.05)	[1]	1.10	[1]
Diluted (loss) earnings per share:
Continuing operations (in dollars per share)	0.01	0.05	0.12	(0.16)	0.10	0.06	0	(1.28)	0.02	[1]	(1.11)	[1]	0.22	[1]
Discontinued operations (in dollars per share)	0	0	(0.01)	(0.02)	0.01	0	(0.02)	0.06	(0.03)	[1]	0.06	[1]	0.87	[1]
Net income (in dollars per share)	$ 0.01	$ 0.05	$ 0.11	$ (0.18)	$ 0.11	$ 0.06	$ (0.02)	$ (1.22)	$ (0.01)	[1]	$ (1.05)	[1]	$ 1.10	[1]

[1] The sum of the earnings per share amounts may not equal the totals due to rounding.