Fixed Assets (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Total fixed assets	$ 46,890		$ 46,890		$ 46,471
Less: Accumulated depreciation and amortization	(29,371)		(29,371)		(25,682)
Fixed assets, net	17,519		17,519		20,789
Depreciation expense	2,111	$ 1,912	4,229	$ 3,651
Cost of revenue [Member]
Property, Plant and Equipment [Line Items]
Depreciation expense	1,434	1,146	2,829	2,235
Sales and marketing [Member]
Property, Plant and Equipment [Line Items]
Depreciation expense	331	341	683	614
General and administrative [Member]
Property, Plant and Equipment [Line Items]
Depreciation expense	203	262	418	505
Product development [Member]
Property, Plant and Equipment [Line Items]
Depreciation expense	143	$ 163	299	$ 297
Computer equipment and software [Member]
Property, Plant and Equipment [Line Items]
Total fixed assets	37,445		37,445		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	$ 6,371		$ 6,371		$ 6,213