Stock-Based Compensation and Employee Benefit Plans (Stock-based Compensation Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 12,515	$ 15,915	$ 11,582
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	2,429	4,002	3,081
Technology and analytics
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	2,300	3,422	2,582
Processing and servicing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	483	869	544
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 7,303	$ 7,622	$ 5,375