CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Income Statement [Abstract]
Service revenues	$ 1,716,335	$ 1,814,834
Costs of services	1,026,603	1,042,988
Gross margin	689,732	771,846
Selling, general and administrative expenses	552,229	514,194
(Income) loss from investments held in employee deferred compensation trusts	(27,291)	30,001
Amortization of intangible assets	721	417
Interest income, net	(4,825)	(166)
Income before income taxes	168,898	227,400
Provision for income taxes	46,893	59,161
Net income	$ 122,005	$ 168,239
Net income per share:
Basic (in usd per share)	$ 1.15	$ 1.54
Diluted (in usd per share)	$ 1.14	$ 1.52
Shares:
Basic (in shares)	106,420	109,218
Diluted (in shares)	107,130	110,591
Dividends declared per share (in usd per share)	$ 0.48	$ 0.43