Segments - Additional Information (Detail)	3 Months Ended			9 Months Ended
	Sep. 30, 2018 USD ($)	[1]	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) segment		Sep. 30, 2017 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment				2
Intersegment sales	$ 619,586,000		$ 577,877,000	$ 1,790,070,000	[1]	$ 1,639,547,000
Intersegment Eliminations
Segment Reporting Information [Line Items]
Intersegment sales				$ 0

[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.