CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities:
Net income	$ 419,416	$ 481,652	$ 327,160
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	92,272	83,401	62,874
Operating lease right-of-use assets amortization expense	47,777	61,750	66,369
Bad debt expense	12,394	2,488	2,253
Deferred taxes	(42,164)	(46,900)	(19,994)
Stock-based compensation expense	99,909	111,655	75,238
Unrealized loss on Derivative	7,904	0	0
Impairment charges	23,619	144	0
Other	32,806	12,993	6,796
Changes in assets and liabilities:
Trade receivables and contract assets	(192,712)	(211,684)	4,235
Prepaid and other assets	(12,140)	(16,182)	6,983
Accounts payable	(2,934)	(2,403)	2,428
Accrued expenses and other liabilities	26,025	155,657	60,133
Operating lease liabilities	(51,668)	(63,812)	(64,453)
Income taxes payable	3,600	3,568	14,385
Net cash provided by operating activities	464,104	572,327	544,407
Cash flows from investing activities:
Purchases of property and equipment	(81,629)	(111,501)	(68,793)
Purchases of short-term investments	(60,000)	0	(120,000)
Proceeds from short-term investments	0	60,000	60,009
Acquisition of businesses, net of cash acquired (Note 3)	(10,644)	(314,958)	(18,888)
Purchases of non-marketable securities	(1,625)	(2,544)	(20,500)
Other investing activities, net	(29,029)	79	1,018
Net cash used in investing activities	(182,927)	(368,924)	(167,154)
Cash flows from financing activities:
Proceeds from issuance of stock under the employee incentive programs	50,660	26,286	26,410
Payments of withholding taxes related to net share settlements of restricted stock units	(26,556)	(41,598)	(20,132)
Proceeds from debt	1,763	31,109	0
Repayment of debt	(15,542)	(31,054)	(18)
Payment of contingent consideration for previously acquired businesses	(6,626)	(40,227)	(7,004)
Purchase of noncontrolling interest	(2,254)	(1,749)	0
Other financing activities, net	(3,466)	(2,324)	(21)
Net cash used in financing activities	(2,021)	(59,557)	(765)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(44,867)	(18,032)	9,357
Net increase in cash, cash equivalents and restricted cash	234,289	125,814	385,845
Cash, cash equivalents and restricted cash, beginning of period	1,449,347	1,323,533	937,688
Cash, cash equivalents and restricted cash, end of period	1,683,636	1,449,347	1,323,533
Cash paid during the year for:
Income taxes, net of refunds	113,188	87,317	54,520
Interest	1,659	413	425
Supplemental disclosure of non-cash investing and financing activities
Acquisition-date fair value of contingent consideration issued for acquisition of businesses	2,645	57,249	7,119
Capital expenditures incurred but not yet paid	$ 57,114	$ 7,738	$ 1,582