Unaudited Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2018	[1]	Jun. 30, 2017	Jun. 30, 2018	[1]	Jun. 30, 2017
Income Statement [Abstract]
Revenues, net	$ 584,985		$ 541,237	$ 1,170,484		$ 1,061,670
Expenses:
Merchant commissions	0		30,619	0		55,003
Processing	111,201		103,322	227,686		205,146
Selling	44,009		38,957	91,120		77,794
General and administrative	96,382		87,587	186,696		183,041
Depreciation and amortization	68,610		64,709	140,112		129,575
Operating income	264,783		216,043	524,870		411,111
Investment loss	0		2,354	0	[2]	4,731	[2]
Other expense (income), net	458		(551)	161		1,645
Interest expense, net	33,150		23,851	64,215		46,978
Total other expense	33,608		25,654	64,376		53,354
Income before income taxes	231,175		190,389	460,494		357,757
Provision for income taxes	54,323		59,402	108,705		103,077
Net income	$ 176,852		$ 130,987	$ 351,789	[2]	$ 254,680	[2]
Earnings per share:
Basic earnings per share (in dollars per share)	$ 1.98		$ 1.42	$ 3.93		$ 2.77
Diluted earnings per share (in dollars per share)	$ 1.91		$ 1.39	$ 3.78		$ 2.70
Weighted average shares outstanding:
Basic weighted average shares outstanding (in shares)	89,169		92,013	89,466		92,060
Diluted weighted average shares outstanding (in shares)	92,702		94,223	92,970		94,392

[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 effective 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.