Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating activities
Net income	$ 839,497	$ 704,216	$ 895,073
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	75,571	65,181	62,784
Stock based compensation	80,071	43,384	60,953
Provision for losses on accounts and other receivables	37,919	158,549	74,309
Amortization of deferred financing costs and discounts	6,831	6,486	5,106
Amortization of intangible assets and premium on receivables	208,625	189,620	211,426
Deferred income taxes	11,026	15,668	37,883
Loss on extinguishment of debt	16,194	0	0
Investment (gain) loss, net	(9)	(30,008)	3,470
Other non-cash operating income	(784)	(1,985)	522
Changes in operating assets and liabilities (net of acquisitions/disposition):
Accounts receivable and other receivables	(731,137)	264,140	(196,028)
Prepaid expenses and other current assets	186,268	(14,521)	(185,391)
Other assets	36,832	12,656	(6,792)
Accounts payable, accrued expenses and customer deposits	430,159	59,203	198,756
Net cash provided by operating activities	1,197,063	1,472,589	1,162,071
Investing activities
Acquisitions, net of cash acquired	(602,120)	(80,787)	(448,277)
Purchases of property and equipment	(111,530)	(78,425)	(75,170)
Proceeds from disposal of investment	0	52,963	0
Other	(2,281)	0	(255)
Net cash used in investing activities	(715,931)	(106,249)	(523,702)
Financing activities
Proceeds from issuance of common stock	48,781	136,797	168,925
Repurchase of common stock	(1,355,722)	(849,910)	(694,909)
Borrowings (payments) on securitization facility, net	418,000	(270,973)	84,973
Deferred financing costs paid and debt discount	(38,920)	(2,637)	(2,868)
Proceeds from issuance of notes payable	1,900,000	0	700,000
Principal payments on notes payable	(507,500)	(175,285)	(138,500)
Borrowings from revolver	1,910,000	1,243,500	1,811,509
Payments on revolver	(1,978,851)	(1,496,907)	(2,292,349)
(Payments) borrowings on swing line of credit, net	(51,049)	(1,042)	52,996
Other	(811)	(344)	52
Net cash provided by (used in) financing activities	343,928	(1,416,801)	(310,171)
Effect of foreign currency exchange rates on cash	(50,984)	(148,157)	(17,854)
Net increase (decrease) in cash and cash equivalents and restricted cash	774,076	(198,618)	310,344
Cash and cash equivalents and restricted cash, beginning of year	1,476,619	1,675,237	1,364,893
Cash and cash equivalents and restricted cash, end of year	2,250,695	1,476,619	1,675,237
Supplemental cash flow information
Cash paid for interest	132,504	126,460	178,417
Cash paid for income taxes	$ 229,721	$ 165,315	$ 200,525