Discontinued Operations - Summary of Pretax Profit (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale of discontinued operations									$ 0	$ 79,318
Income from discontinued operations, net of tax	$ 0	$ 0	$ 0	$ 0	$ (401)	$ (967)	$ 58,783	$ 18,881	0	76,296	$ 7,104
Discontinued Operations, Disposed of by Sale | GS segment
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenue									0	27,737
Direct costs									0	19,494
Gross profit									0	8,243
Selling, general and administrative expenses									0	6,988
Depreciation and amortization									0	307
Income from discontinued operations									0	948
Gain on sale of discontinued operations	$ (300)	$ (400)	$ 80,000						0	79,318
Other (expense) income, net									0	(436)
Income from discontinued operations, before income taxes									0	79,830
Income tax expense									0	3,534
Income from discontinued operations, net of tax									$ 0	$ 76,296
Discontinued Operations, Held-for-sale | GS segment
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenue											114,416
Direct costs											82,295
Gross profit											32,121
Selling, general and administrative expenses											21,862
Depreciation and amortization											995
Income from discontinued operations											9,264
Gain on sale of discontinued operations											0
Other (expense) income, net											9
Income from discontinued operations, before income taxes											9,273
Income tax expense											2,169
Income from discontinued operations, net of tax											$ 7,104