Unaudited Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	[1]	Jun. 30, 2019		Jun. 30, 2018	[1]
Income Statement [Abstract]
Revenues, net	$ 647,094	$ 584,985		$ 1,268,919		$ 1,170,484
Expenses:
Processing	120,458	111,201		249,572		227,686
Selling	51,856	44,009		101,117		91,120
General and administrative	106,784	96,431		199,568		186,800
Depreciation and amortization	70,908	68,610		138,353		140,112
Other operating, net	(229)	(49)		(1,184)		(104)
Operating income	297,317	264,783		581,493		524,870
Investment loss	0	0		15,660	[2]	0
Other expense, net	528	458		748		161
Interest expense, net	39,529	33,150		78,584		64,215
Total other expense	40,057	33,608		94,992		64,376
Income before income taxes	257,260	231,175		486,501		460,494
(Benefit from) provision for income taxes	(4,391)	54,323		52,743		108,705
Net income	$ 261,651	$ 176,852		$ 433,758	[2]	$ 351,789
Earnings per share:
Basic earnings per share (in dollars per share)	$ 3.03	$ 1.98		$ 5.03		$ 3.93
Diluted earnings per share (in dollars per share)	$ 2.90	$ 1.91		$ 4.84		$ 3.78
Weighted average shares outstanding:
Basic (in shares)	86,360	89,169		86,159		89,466
Diluted (in shares)	90,131	92,702		89,694		92,970

[1] Reflects reclassifications from previously disclosed amounts to conform to current presentation.

[2] Reflects the impact of the Company's adoption of ASU 2016-02 "Leases", on January 1, 2019, using the modified retrospective transition method. Under this method, financial results reported in periods prior to 2019 are unchanged. Refer to footnote 2.