Consolidated Statements of Cash Flows - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018		Dec. 31, 2017	Dec. 31, 2016
Operating activities
Net income	[2]	$ 811,483	[1]	$ 740,200	$ 452,385
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	[2]	52,936		46,599	36,456
Stock-based compensation	[2]	69,939		93,297	63,946
Provision for losses on accounts receivable	[2]	64,377		44,857	35,885
Amortization of deferred financing costs and discounts	[2]	5,342		6,952	7,582
Amortization of intangible assets	[2]	216,330		211,849	161,635
Amortization of premium on receivables	[2]	5,343		6,112	5,165
Loss on extinguishment of debt	[2]	2,098	[1]	3,296	0
Write-off of fixed assets	[2]	8,793		0	0
Deferred income taxes	[2]	(2,750)		(247,712)	(28,681)
Investment loss	[2]	7,147	[1]	53,164	36,356
Gain on sale of assets/business	[2]	(152,750)		(174,983)	0
Other non-cash operating income	[2]	(186)		(61)	(690)
Changes in operating assets and liabilities (net of acquisitions/disposition):
Accounts receivable and other receivables	[2]	(159,024)		(431,003)	(338,796)
Prepaid expenses and other current assets	[2]	(27,650)		26,102	5,301
Other assets	[2]	(25,432)		(20,957)	(20,345)
Accounts payable, accrued expenses and customer deposits	[2]	27,386		322,346	292,019
Net cash provided by operating activities	[2]	903,382		680,058	708,218
Investing activities
Acquisitions, net of cash acquired	[2]	(20,843)		(705,257)	(1,331,985)
Purchases of property and equipment	[2]	(81,387)		(70,093)	(59,011)
Proceeds from disposal of an asset/business	[2]	98,735		316,501	0
Other	[2]	(22,775)		(38,953)	1,411
Net cash used in investing activities	[2]	(26,270)		(497,802)	(1,389,585)
Financing activities
Proceeds from issuance of common stock	[2]	55,680		44,690	21,231
Repurchase of common stock	[2]	(958,696)		(402,393)	(187,678)
Borrowings (payments) on securitization facility, net	[2]	75,000		220,000
Borrowings (payments) on securitization facility, net	[2]				(23,000)
Deferred financing costs paid and debt discount	[2]	(4,927)		(12,908)	(2,272)
Proceeds from issuance of notes payable	[2]	363,430		780,656	600,000
Principal payments on notes payable	[2]	(498,305)		(423,156)	(118,500)
Borrowings from revolver	[2]	1,493,091		1,100,000	1,225,107
Payments on revolver	[2]	(1,099,040)		(1,031,722)	(786,849)
(Payments) borrowings on swing line of credit, net	[2]	(4,935)		(23,686)
(Payments) borrowings on swing line of credit, net	[2]				26,606
Other	[2]	887		457	(676)
Net cash (used in) provided by financing activities	[2]	(577,815)		251,938	753,969
Effect of foreign currency exchange rates on cash	[2]	(65,274)		52,906	(43,476)
Net increase in cash and cash equivalents and restricted cash	[2]	234,023		487,100	29,126
Cash and cash equivalents and restricted cash, beginning of year	[2]	1,130,870		643,770	614,644
Cash and cash equivalents and restricted cash, end of year	[2]	1,364,893		1,130,870	643,770
Supplemental cash flow information
Cash paid for interest	[2]	156,749		113,416	70,339
Cash paid for income taxes	[2]	207,504		392,192	101,951
Non cash investing activity, notes assumed in acquisitions	[2]	$ 0		$ 29,341	$ 0

[1] Reflects the impact of the Company's adoption of Accounting Standards Update 2014-09, Revenue from Contracts with Customers (Topic 606) ("ASC 606") and related cost capitalization guidance, which was adopted by the Company on January 1, 2018 using the modified retrospective transition method. The adoption of ASC 606 resulted in an adjustment to retained earnings in our consolidated balance sheet for the cumulative effect of applying the standard, which included costs incurred to obtain a contract, as well as presentation changes in our statements of income, including the classification of certain amounts previously classified as merchant commissions and processing expense net with revenues. As a result of the application of the modified retrospective transition method, the Company's prior period results within its Form 10-K and quarterly reports on Form 10-Q will not be restated to reflect ASC 606.

[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 statement of cash flows.