Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 168,239	$ 110,598
Adjustments to reconcile net income to net cash provided by operating activities:
Allowance for credit losses	2,065	3,157
Depreciation	11,080	13,962
Amortization of cloud computing implementation costs	7,113	9,957
Amortization of intangible assets	417	576
Realized and unrealized (gains) losses from investments held in employee deferred compensation trusts	30,296	(11,694)
Stock-based compensation	15,184	14,182
Deferred income taxes	5,493	2,584
Changes in operating assets and liabilities:
Accounts receivable	(89,597)	(95,024)
Capitalized cloud computing implementation costs	(9,464)	(8,488)
Accounts payable and accrued expenses	(14,072)	(6,603)
Accrued payroll and benefit cost	(39,435)	13,009
Employee deferred compensation plan obligations	(39,976)	2,586
Income taxes payable	35,310	25,409
Other assets and liabilities, net	(13,491)	(6,155)
Net cash flows provided by operating activities	69,162	68,056
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	(14,987)	(9,739)
Investments in employee deferred compensation trusts	(33,913)	(28,509)
Proceeds from employee deferred compensation trust redemptions	21,782	22,799
Net cash flows used in investing activities	(27,118)	(15,449)
CASH FLOWS FROM FINANCING ACTIVITIES:
Repayment of notes payable	0	(58)
Repurchases of common stock	(62,062)	(79,465)
Dividends paid	(47,498)	(44,277)
Net cash flows used in financing activities	(109,560)	(123,800)
Effect of exchange rate fluctuations	(1,155)	(5,303)
Change in cash and cash equivalents	(68,671)	(76,496)
Cash and cash equivalents at beginning of period	619,001	574,426
Cash and cash equivalents at end of period	550,330	497,930
Non-cash items:
Stock repurchases awaiting settlement	5,872	3,912
Fund exchanges within employee deferred compensation trusts	$ 40,509	$ 37,661