Revenue (Disaggregation of Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Total	$ 113,971	$ 114,846	$ 357,120	$ 358,015
Benefit Administration Service and COBRA
Disaggregation of Revenue [Line Items]
Total	95,212	99,482	295,911	305,405
Interchange
Disaggregation of Revenue [Line Items]
Total	11,161	10,972	40,461	39,924
Other revenue
Disaggregation of Revenue [Line Items]
Total	$ 7,598	$ 4,392	$ 20,748	$ 12,686