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	$ 70,988	$ 72,398
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and intangible assets amortization	29,080	27,082
Operating lease right-of-use assets expense	5,553	5,699
Deferred income tax benefit	(861)	(3,564)
Provision for bad debts	2,326	18
Stock-based compensation expense	35,651	35,119
Other	919	975
Changes in operating assets and liabilities:
Accounts receivable	180,259	159,038
Other receivables and current assets	43,479	(12,071)
Other long-term assets	(5,983)	(1,909)
Accounts payable, accrued expenses and current liabilities	(143,883)	(80,050)
Accrued income taxes	(1,119)	(20,954)
Deferred revenue	455	1,204
Other long-term liabilities	(5,928)	(11,878)
Net cash provided by operating activities	210,936	171,107
Cash flows from investing activities:
Acquisitions, net of cash acquired	(4,915)	(10,783)
Capital expenditures	(5,062)	(5,045)
Other investing activities	13	(35)
Net cash used in investing activities	(9,964)	(15,863)
Cash flows from financing activities:
Purchase of treasury stock	(155,571)	0
Restricted stock withholding taxes paid in lieu of issued shares	(59,196)	(86,049)
Proceeds from shares issued for stock-based compensation	10,122	11,892
Other financing activities	0	(51)
Net cash used in financing activities	(204,645)	(74,208)
Effect of exchange rate fluctuations on cash and cash equivalents	(6,573)	(6,281)
Net (decrease) increase in cash and cash equivalents	(10,246)	74,755
Cash and cash equivalents, beginning of period	667,667	912,672
Cash and cash equivalents, end of period	657,421	987,427
Supplemental disclosure of cash flow information:
Income taxes paid	3,566	20,641
Interest paid	$ 2,626	$ 2,956