CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 122,005	$ 168,239
Adjustments to reconcile net income to net cash provided by operating activities:
Allowance for credit losses	2,934	2,065
Depreciation	12,738	11,080
Amortization of cloud computing implementation costs	8,188	7,113
Amortization of intangible assets	721	417
Realized and unrealized (gains) losses from investments held in employee deferred compensation trusts	(25,728)	30,296
Stock-based compensation	15,434	15,184
Deferred income taxes	3,102	5,493
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable	9,772	(89,597)
Capitalized cloud computing implementation costs	(10,457)	(9,464)
Accounts payable and accrued expenses	(10,216)	(14,072)
Accrued payroll and benefit costs	(91,740)	(39,435)
Employee deferred compensation plan obligations	21,970	(39,976)
Income taxes payable	29,909	35,310
Other assets and liabilities, net	(23,109)	(13,491)
Net cash flows provided by operating activities	65,523	69,162
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	(9,369)	(14,987)
Investments in employee deferred compensation trusts	(71,302)	(33,913)
Proceeds from employee deferred compensation trust redemptions	18,600	21,782
Payments for acquisition	(700)	0
Net cash flows used in investing activities	(62,771)	(27,118)
CASH FLOWS FROM FINANCING ACTIVITIES:
Repurchases of common stock	(63,244)	(62,062)
Dividends paid	(53,717)	(47,498)
Net cash flows used in financing activities	(116,961)	(109,560)
Effect of exchange rate fluctuations	3,312	(1,155)
Change in cash and cash equivalents	(110,897)	(68,671)
Cash and cash equivalents at beginning of period	658,626	619,001
Cash and cash equivalents at end of period	547,729	550,330
Non-cash items:
Repurchases of common stock awaiting settlement	0	5,872
Fund exchanges within employee deferred compensation trusts	50,213	40,509
Contingent consideration related to acquisition	$ 600	$ 0