Supplementary Balance Sheet Information - Contract Acquisition Costs, Net (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Contract Acquisition Costs, Net
Finite-Lived Intangible Assets, Net	$ 223,647		$ 223,647		$ 235,700
Conversion costs
Contract Acquisition Costs, Net
Finite-Lived Intangible Assets, Net	140,614		140,614		144,173
Accumulated amortization	173,700		173,700		164,400
Amortization expense	7,266	$ 6,872	22,596	$ 21,311
Payments for processing rights
Contract Acquisition Costs, Net
Finite-Lived Intangible Assets, Net	83,033		83,033		91,527
Accumulated amortization	164,200		164,200		$ 145,300
Amortization expense	$ 5,076	$ 4,927	$ 15,405	$ 14,871