Unaudited Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended			12 Months Ended
	Mar. 31, 2019	[1]	Mar. 31, 2018	Dec. 31, 2018
Operating activities
Net income	$ 172,107		$ 174,937
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	15,132		12,397
Stock-based compensation	12,541		14,403
Provision for losses on accounts receivable	22,164		11,997
Amortization of deferred financing costs and discounts	1,205		1,339
Amortization of intangible assets and premium on receivables	52,313		59,105
Deferred income taxes	(2,696)		(4,829)
Investment loss	15,660		0
Other non-cash operating income	(1,574)		(57)
Changes in operating assets and liabilities (net of acquisitions):
Accounts and other receivables	(302,395)		(288,152)
Prepaid expenses and other current assets	644		32,074
Other assets	(14,517)		(7,101)
Accounts payable, accrued expenses and customer deposits	326,910		194,589
Net cash provided by operating activities	297,494		200,702
Investing activities
Acquisitions, net of cash acquired	0		(3,875)
Purchases of property and equipment	(14,506)		(15,214)
Other	0		(3,642)
Net cash used in investing activities	(14,506)		(22,731)
Financing activities
Proceeds from issuance of common stock	29,795		19,975
Repurchase of common stock	(3,322)		(88,292)
Borrowings on securitization facility, net	56,000		18,000
Deferred financing costs paid and debt discount	(284)		0
Principal payments on notes payable	(32,438)		(34,500)
Borrowings from revolver	0		420,258
Payments on revolver	(353,638)		(439,351)
Borrowings on swing line of credit, net	31,032		5,009
Other	(63)		(92)
Net cash used in financing activities	(272,918)		(98,993)
Effect of foreign currency exchange rates on cash	(2,392)		12,653
Net increase in cash and cash equivalents and restricted cash	7,678		91,631
Cash and cash equivalents and restricted cash, beginning of period	1,364,893		1,130,870	$ 1,130,870
Cash and cash equivalents and restricted cash, end of period	1,372,571		1,222,501	$ 1,364,893	[1]
Supplemental cash flow information
Cash paid for interest	46,904		35,634
Cash paid for income taxes	$ 17,894		$ 16,830

[1] Reflects the impact of the Company's adoption of Accounting Standards Update 2016-18, "Statement of Cash Flows (Topic 230)", which was adopted by the Company on January 1, 2018 and applied retrospectively to results for 2017. The adoption of Topic 230 resulted in the statement of cash flows presenting the changes in the total of cash, cash equivalents and restricted cash. As a result, the Company will no longer present transfers between cash and cash equivalents and restricted cash in the statement of cash flows.