Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Income Statement [Abstract]
Revenues	$ 6,493,167	$ 5,620,822	$ 17,119,373	$ 15,098,258
Cost of services	5,480,597	4,773,498	14,671,978	12,953,640
Gross profit	1,012,570	847,324	2,447,395	2,144,618
Equity in earnings of integral unconsolidated affiliates	14,015	11,707	34,935	30,697
Selling, general and administrative expenses	(483,878)	(386,538)	(1,318,574)	(1,155,261)
Amortization of intangible assets	(110,422)	(71,361)	(267,147)	(213,789)
Change in fair value of contingent consideration liabilities	(1,124)	(803)	(2,864)	(803)
Operating income	431,161	400,329	893,745	805,462
Interest and other financing expenses	(59,950)	(47,531)	(146,343)	(137,413)
Interest income	7,237	1,993	18,817	4,957
Other income (expense), net	2,994	(3,744)	29,493	7,541
Income before income taxes	381,442	351,047	795,712	680,547
Provision for income taxes	82,421	77,522	178,716	143,468
Net income	299,021	273,525	616,996	537,079
Less: Net income attributable to non-controlling interests	5,836	689	17,292	3,298
Net income attributable to common stock	$ 293,185	$ 272,836	$ 599,704	$ 533,781
Earnings per share attributable to common stock:
Basic (in dollars per share)	$ 1.99	$ 1.88	$ 4.09	$ 3.68
Diluted (in dollars per share)	$ 1.95	$ 1.83	$ 4.00	$ 3.59
Shares used in computing earnings per share:
Weighted average basic shares outstanding (in shares)	147,394	145,455	146,639	145,118
Weighted average diluted shares outstanding (in shares)	150,556	148,792	149,911	148,749