Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Income Statement [Abstract]
Revenues	$ 3,788,857	$ 3,698,652	$ 3,489,242
Operating expenses
Direct cost of revenues	2,571,382	2,516,726	2,354,216
Selling, general and administrative expenses	799,624	822,151	751,306
Special charges	25,295	8,230	0
Amortization of intangible assets	3,479	4,183	6,159
Costs and expenses	3,399,780	3,351,290	3,111,681
Operating income	389,077	347,362	377,561
Other income (expense)
Interest income and other	3,330	10,360	(4,867)
Interest expense	(21,396)	(6,951)	(14,331)
Other income (expense)	(18,066)	3,409	(19,198)
Total	371,011	350,771	358,363
Income tax provision	100,140	70,683	83,471
Net income	$ 270,871	$ 280,088	$ 274,892
Earnings per common share — basic (in dollars per share)	$ 8.33	$ 7.96	$ 8.10
Earnings per common share — diluted (in dollars per share)	$ 8.24	$ 7.81	$ 7.71
Other comprehensive income (loss), net of tax
Foreign currency translation adjustments, net of tax expense of $—, $— and $—	$ 46,968	$ (26,112)	$ 26,262
Total other comprehensive income (loss), net of tax	46,968	(26,112)	26,262
Comprehensive income	$ 317,839	$ 253,976	$ 301,154