Unaudited Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended			12 Months Ended
	Mar. 31, 2018		Mar. 31, 2017	Dec. 31, 2017
Operating activities
Net income	$ 174,937	[1],[2]	$ 123,693
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	12,397	[2]	10,667
Stock-based compensation	14,403	[2]	23,093
Provision for losses on accounts receivable	11,997	[2]	12,988
Amortization of deferred financing costs and discounts	1,339	[2]	1,914
Amortization of intangible assets	57,836	[2]	52,654
Amortization of premium on receivables	1,269	[2]	1,544
Deferred income taxes	(4,829)	[2]	(3,453)
Investment loss	0	[1],[2]	2,377
Other	(57)	[2]	0
Changes in operating assets and liabilities (net of acquisitions):
Accounts and other receivables	(288,152)	[2]	(236,564)
Prepaid expenses and other current assets	32,074	[2]	(16,453)
Other assets	(7,101)	[2]	(2,673)
Accounts payable, accrued expenses and customer deposits	194,589	[2]	103,711
Net cash provided by operating activities	200,702	[2]	73,498
Investing activities
Acquisitions, net of cash acquired	(3,875)	[2]	0
Purchases of property and equipment	(15,214)	[2]	(14,796)
Other	(3,642)	[2]	(6,327)	$ (39,000)
Net cash used in investing activities	(22,731)	[2]	(21,123)
Financing activities
Proceeds from issuance of common stock	19,975	[2]	15,230
Repurchase of common stock	(88,292)	[2]	0
Borrowings on securitization facility, net	18,000	[2]	85,000
Principal payments on notes payable	(34,500)	[2]	(33,363)
Borrowings from revolver	420,258	[2]	90,000
Payments on revolver	(439,351)	[2]	(159,949)
Borrowings on swing line of credit, net	5,009	[2]	21,639
Other	(92)	[2]	537
Net cash (used in) provided by financing activities	(98,993)	[2]	19,094
Effect of foreign currency exchange rates on cash	12,653	[2]	19,754
Net increase in cash and cash equivalents and restricted cash	91,631	[2]	91,223
Cash and cash equivalents and restricted cash, beginning of period	1,130,870		643,770	643,770
Cash and cash equivalents and restricted cash, end of period	1,222,501	[2]	734,993	$ 1,130,870
Supplemental cash flow information
Cash paid for interest	35,634	[2]	33,190
Cash paid for income taxes	$ 16,830	[2]	$ 88,503

[1] Reflects the January 1, 2018 adoption of Accounting Standards Update 2014-09, "Revenue from Contracts with Customers (Topic 606)" using the modified retrospective transition method. As a result of the application of the modified retrospective transition method, the Company's prior period results within its annual report on Form 10-K and quarterly reports on Form 10-Q will not be restated to reflect the impact of Topic 606. See footnote 1.

[2] 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 consolidated statement of cash flows.