Supplementary Balance Sheet Information - Contract Acquisition Costs, Net (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Contract Acquisition Costs, Net
Finite-Lived Intangible Assets, Net	$ 227,659		$ 227,659		$ 235,700
Conversion costs
Contract Acquisition Costs, Net
Finite-Lived Intangible Assets, Net	140,478		140,478		144,173
Accumulated amortization	168,500		168,500		164,400
Amortization expense	7,157	$ 7,282	15,330	$ 14,440
Payments for processing rights
Contract Acquisition Costs, Net
Finite-Lived Intangible Assets, Net	87,181		87,181		91,527
Accumulated amortization	156,700		156,700		$ 145,300
Amortization expense	$ 5,110	$ 5,014	$ 10,329	$ 9,943