CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Statement [Abstract]
Revenues	$ 4,690,540	$ 4,824,698	$ 3,758,144
Operating expenses:
Cost of revenues (exclusive of depreciation and amortization)	3,256,514	3,286,683	2,483,697
Selling, general and administrative expenses	815,065	872,777	648,736
Depreciation and amortization expense	91,800	92,272	83,395
Loss on sale of business	25,922	0	0
Income from operations	501,239	572,966	542,316
Interest and other income/(loss), net	51,124	10,025	(1,727)
Foreign exchange loss	(15,778)	(75,733)	(7,197)
Income before provision for income taxes	536,585	507,258	533,392
Provision for income taxes	119,502	87,842	51,740
Net income	$ 417,083	$ 419,416	$ 481,652
Net income per share:
Basic (in dollars per share)	$ 7.21	$ 7.32	$ 8.52
Diluted (in dollars per share)	$ 7.06	$ 7.09	$ 8.15
Shares used in calculation of net income per share:
Basic (in shares)	57,829	57,291	56,511
Diluted (in shares)	59,085	59,169	59,064