Intangible Assets - Schedule of Amortization Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Total amortization	$ 4,041	$ 4,134	$ 4,251
Acquired technology and domain name
Finite-Lived Intangible Assets [Line Items]
Total amortization	3,041	3,047	3,164
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Total amortization	673	760	760
Trade names
Finite-Lived Intangible Assets [Line Items]
Total amortization	$ 327	$ 327	$ 327