Fixed Assets (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Total fixed assets	$ 46,928		$ 46,928		$ 46,471
Less: Accumulated depreciation and amortization	(31,228)		(31,228)		(25,682)
Fixed assets, net	15,700		15,700		20,789
Depreciation expense	2,045	$ 1,863	6,274	$ 5,514
Cost of revenue [Member]
Property, Plant and Equipment [Line Items]
Depreciation expense	1,419	1,181	4,248	3,416
Sales and marketing [Member]
Property, Plant and Equipment [Line Items]
Depreciation expense	302	304	985	918
General and administrative [Member]
Property, Plant and Equipment [Line Items]
Depreciation expense	190	245	608	750
Product development [Member]
Property, Plant and Equipment [Line Items]
Depreciation expense	134	$ 133	433	$ 430
Computer equipment and software [Member]
Property, Plant and Equipment [Line Items]
Total fixed assets	37,499		37,499		37,200
Furniture, fixtures and office equipment [Member]
Property, Plant and Equipment [Line Items]
Total fixed assets	3,074		3,074		3,058
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Total fixed assets	$ 6,355		$ 6,355		$ 6,213