Goodwill and Intangible Assets - Summary of Identifiable Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross	$ 283,108	$ 270,131
Accumulated Amortization	(100,557)	(75,459)
Net	182,551	194,672
Acquired Internal Use Software
Finite-Lived Intangible Assets [Line Items]
Gross	14,000	14,000
Accumulated Amortization	(14,000)	(12,665)
Net	0	1,335
Technology
Finite-Lived Intangible Assets [Line Items]
Gross	68,550	68,550
Accumulated Amortization	(25,639)	(18,529)
Net	42,911	50,021
Merchant Relationships
Finite-Lived Intangible Assets [Line Items]
Gross	181,000	181,000
Accumulated Amortization	(56,018)	(40,934)
Net	124,982	140,066
Other Intangibles
Finite-Lived Intangible Assets [Line Items]
Gross	19,558	6,581
Accumulated Amortization	(4,900)	(3,331)
Net	$ 14,658	$ 3,250