Stock-based Compensation Plans and Awards - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Stock-based Compensation Plans and Awards
Stock-based compensation expense	$ 9,364	$ 9,431
Service costs
Stock-based Compensation Plans and Awards
Stock-based compensation expense	1,139	699
Sales and marketing
Stock-based Compensation Plans and Awards
Stock-based compensation expense	843	937
Product development
Stock-based Compensation Plans and Awards
Stock-based compensation expense	2,536	2,278
General and administrative
Stock-based Compensation Plans and Awards
Stock-based compensation expense	$ 4,846	$ 5,517