CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 251,598	$ 411,146	$ 657,919
Adjustments to reconcile net income to net cash provided by operating activities:
Allowance for credit losses	5,286	8,752	8,771
Depreciation	52,053	51,364	47,398
Amortization of cloud computing implementation costs	36,045	44,720	28,925
Amortization of intangible assets	1,217	2,883	1,667
Realized and unrealized (gains) losses from investments held in employee deferred compensation trusts	(71,656)	(72,971)	98,776
Stock-based compensation	63,448	61,139	57,663
Deferred income taxes	(17,936)	(16,568)	10,810
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable	66,954	156,269	(65,626)
Capitalized cloud computing implementation costs	(29,210)	(34,895)	(40,357)
Accounts payable and accrued expenses	16,047	(14,698)	3,735
Accrued payroll and benefit cost	(32,963)	(61,725)	(58,067)
Employee deferred compensation plan obligations	105,490	98,802	(61,165)
Income taxes payable	(20,960)	10,721	2,596
Other assets and liabilities, net	(14,944)	(8,058)	(9,295)
Net cash flows provided by operating activities	410,469	636,881	683,750
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	(56,318)	(45,874)	(61,120)
Investments in employee deferred compensation trusts	(69,237)	(102,969)	(67,388)
Proceeds from employee deferred compensation trust redemptions	38,700	37,628	30,869
Payments for acquisitions, net of cash acquired	(264)	(1,035)	(18,984)
Net cash flows used in investing activities	(87,119)	(112,250)	(116,623)
CASH FLOWS FROM FINANCING ACTIVITIES:
Repurchases of common stock	(276,032)	(254,625)	(319,897)
Dividends paid	(220,409)	(205,910)	(189,286)
Net cash flows used in financing activities	(496,441)	(460,535)	(509,183)
Effect of exchange rate fluctuations	(21,066)	9,018	(18,319)
Change in cash and cash equivalents	(194,157)	73,114	39,625
Cash and cash equivalents at beginning of period	731,740	658,626	619,001
Cash and cash equivalents at end of period	537,583	731,740	658,626
Cash paid during the year for:
Interest	272	315	368
Income taxes, net of refunds	143,615	168,488	217,927
Non-cash items:
Repurchases of common stock awaiting settlement	0	4,394	3,504
Fund exchanges within employee deferred compensation trusts	130,997	114,821	103,003
Contingent consideration related to acquisition	$ 0	$ 350	$ 1,300