Unaudited Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2018		Sep. 30, 2017	Sep. 30, 2018		Sep. 30, 2017
Income Statement [Abstract]
Revenues, net	$ 619,586	[1]	$ 577,877	$ 1,790,070	[1]	$ 1,639,547
Expenses:
Merchant commissions	0	[1]	27,687	0	[1]	82,690
Processing	128,400	[1]	111,283	356,086	[1]	316,429
Selling	44,806	[1]	45,060	135,926	[1]	122,854
General and administrative	98,023	[1]	92,054	284,718	[1]	275,095
Depreciation and amortization	67,267	[1]	69,156	207,379	[1]	198,731
Operating income	281,090	[1]	232,637	805,961	[1]	643,748
Investment loss	7,147	[1]	47,766	7,147	[1],[2]	52,497	[2]
Other expense (income), net	303	[1]	(175,271)	465	[1]	(173,626)
Interest expense, net	36,072	[1]	29,344	100,287	[1]	76,322
Loss on extinguishment of debt	0		(3,296)	0		(3,296)
Total other expense (income)	43,522	[1]	(94,865)	107,899	[1]	(41,511)
Income before income taxes	237,568	[1]	327,502	698,062	[1]	685,259
Provision for income taxes	79,874	[1]	124,679	188,579	[1]	227,756
Net income	$ 157,694	[1]	$ 202,823	$ 509,483	[1],[2]	$ 457,503	[2]
Earnings per share:
Basic earnings per share (in dollars per share)	$ 1.78	[1]	$ 2.23	$ 5.72	[1]	$ 4.99
Diluted earnings per share (in dollars per share)	$ 1.71	[1]	$ 2.18	$ 5.50	[1]	$ 4.87
Weighted average shares outstanding:
Basic weighted average shares outstanding (in shares)	88,456	[1]	90,751	89,126	[1]	91,619
Diluted weighted average shares outstanding (in shares)	92,081	[1]	93,001	92,671	[1]	93,923

[1] Reflects the impact of the Company's adoption of 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 annual report on Form 10-K and quarterly reports on Form 10-Q will not be restated to reflect the impact of ASC 606. See footnote 1, "Summary of Significant Accounting Policies", in the accompanying notes to the unaudited consolidated financial statements.

[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.