Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Statement of Comprehensive Income [Abstract]
Revenue	$ 391,722	$ 300,730
Operating expenses	290,299	223,971
Gross margin	101,423	76,759
Corporate general and administrative expenses	16,309	14,483
Operating income	85,114	62,276
Other income (expense):
Interest expense	(1,259)	(877)
Other (expense) income, net	(6,403)	4,789
Total other (expense) income, net	(7,662)	3,912
Income from continuing operations before income tax    expense	77,452	66,188
Income tax expense	19,321	15,972
Income from continuing operations	58,131	50,216
Loss from discontinued operations, net of tax	(4)	(7)
Net income	$ 58,127	$ 50,209
Basic:
Continuing operations (in dollars per share)	$ 1.12	$ 0.94
Discontinued operations (in dollars per share)	0	0
Net income (in dollars per share)	1.12	0.94
Diluted:
Continuing operations (in dollars per share)	1.10	0.92
Discontinued operations (in dollars per share)	0	0
Net income (in dollars per share)	$ 1.10	$ 0.92
Basic weighted average shares outstanding (in shares)	52,119	53,366
Diluted weighted average shares outstanding (in shares)	52,955	54,436
Comprehensive income:
Net income	$ 58,127	$ 50,209
Other comprehensive income, net of tax	1,925	854
Comprehensive income	$ 60,052	$ 51,063