Discontinued Operations - Summary of Pretax Profit (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale of discontinued operations			$ 80,004	$ 0
Income from discontinued operations, net of tax	$ 58,783	$ 1,099	77,664	2,317
Discontinued Operations, Disposed of by Sale | GS segment
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenue	1,311	29,089	27,737	57,941
Direct costs	479	21,826	19,494	42,999
Gross profit	832	7,263	8,243	14,942
Selling, general and administrative expenses	1,424	5,534	6,842	11,329
Depreciation and amortization	58	245	307	501
(Loss) income from discontinued operations	(650)	1,484	1,094	3,112
Gain on sale of discontinued operations	80,004	0	80,004	0
Other income (expense), net	428	(11)	(436)	(8)
Income from discontinued operations, before income taxes	79,782	1,473	80,662	3,104
Tax expense (benefit)	20,999	374	2,998	787
Income from discontinued operations, net of tax	$ 58,783	$ 1,099	$ 77,664	$ 2,317