Goodwill and Intangible Assets - Summary of Identifiable Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross	$ 305,715	$ 283,108
Accumulated Amortization	(130,115)	(100,557)
Net	175,600	182,551
Acquired Internal Use Software
Finite-Lived Intangible Assets [Line Items]
Gross	14,000	14,000
Accumulated Amortization	(14,000)	(14,000)
Net	0	0
Technology
Finite-Lived Intangible Assets [Line Items]
Gross	68,550	68,550
Accumulated Amortization	(32,749)	(25,639)
Net	35,801	42,911
Merchant Relationships
Finite-Lived Intangible Assets [Line Items]
Gross	181,000	181,000
Accumulated Amortization	(71,101)	(56,018)
Net	109,899	124,982
Other Intangibles
Finite-Lived Intangible Assets [Line Items]
Gross	42,165	19,558
Accumulated Amortization	(12,265)	(4,900)
Net	$ 29,900	$ 14,658