Goodwill and Intangible Assets - Intangible assets, net (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Intangible assets with finite lives:
Net	$ 266,302		$ 266,302		$ 286,267
Accumulated impairment losses			(6,632)
Total intangible assets, net	270,174		270,174		290,139
Amortization expense related to intangible assets	11,600	$ 11,500	24,100	$ 22,200
Trademarks
Intangible assets with finite lives:
Gross carrying value	18,499		18,499		18,499
Accumulated impairment losses			(14,627)		(14,627)
Net	3,872		3,872		3,872
Merchant contract portfolios
Intangible assets with finite lives:
Gross carrying value	293,069		293,069		293,069
Accumulated amortization	(151,399)		(151,399)		(139,159)
Accumulated impairment losses	(7,089)		(7,089)		(5,658)
Foreign currency translation adjustment	(26,464)		(26,464)		(27,975)
Net	108,117		108,117		120,277
Marketing alliance agreements
Intangible assets with finite lives:
Gross carrying value	191,879		191,879		191,879
Accumulated amortization	(53,742)		(53,742)		(47,777)
Accumulated impairment losses	(11,920)		(11,920)		(7,585)
Foreign currency translation adjustment	(17,645)		(17,645)		(18,634)
Net	108,572		108,572		117,883
Trademarks
Intangible assets with finite lives:
Gross carrying value	28,657		28,657		28,657
Accumulated amortization	(11,940)		(11,940)		(10,748)
Foreign currency translation adjustment	(4,366)		(4,366)		(4,446)
Net	12,351		12,351		13,463
Internally developed software
Intangible assets with finite lives:
Gross carrying value	69,213		69,213		60,876
Accumulated amortization	(20,224)		(20,224)		(15,794)
Accumulated impairment losses	(10,190)		(10,190)		(9,324)
Foreign currency translation adjustment	(2,372)		(2,372)		(2,260)
Net	36,427		36,427		33,498
Non-competition agreements
Intangible assets with finite lives:
Gross carrying value	6,462		6,462		6,462
Accumulated amortization	(5,627)		(5,627)		(5,316)
Net	$ 835		$ 835		$ 1,146