Property and Equipment - Schedule of Depreciation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property and Equipment
Depreciation	$ 6,075	$ 7,190	$ 11,178
Accelerated depreciation	400	1,200	2,100
Product costs
Property and Equipment
Depreciation	252
Service costs
Property and Equipment
Depreciation	3,092	3,563	5,965
Sales and marketing
Property and Equipment
Depreciation	36	49	67
Product development
Property and Equipment
Depreciation	91	138	200
General and administrative
Property and Equipment
Depreciation	$ 2,604	$ 3,440	$ 4,946