Summary of Significant Accounting Policies - Goodwill, Deferred Rent Liability, Advertising Costs, Foreign Currency Translation (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) segment item	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Goodwill and Intangible Assets, Net
Number of operating segments | segment	1
Number of reportable segments | segment	1
Number of reporting units | item	1
Impairment of goodwill	$ 0	$ 20,890	$ 0
Revenue Recognition and Deferred Revenue
Term of license	1 year
Deferred revenue	$ 5	108
Sales and Marketing Expenses
Advertising costs	18	26	688
Foreign Currency Translation Adjustments
Foreign currency translation adjustments	276	153	97
Net (losses) gains resulting from transactions denominated in foreign currencies	$ (21)	$ (4)	$ (14)
Technology | Minimum
Goodwill and Intangible Assets, Net
Finite-Lived Intangible Asset, Useful Life	5 years
Technology | Maximum
Goodwill and Intangible Assets, Net
Finite-Lived Intangible Asset, Useful Life	7 years
Customer relationships | Minimum
Goodwill and Intangible Assets, Net
Finite-Lived Intangible Asset, Useful Life	5 years
Customer relationships | Maximum
Goodwill and Intangible Assets, Net
Finite-Lived Intangible Asset, Useful Life	10 years
Trademarks and trade name | Minimum
Goodwill and Intangible Assets, Net
Finite-Lived Intangible Asset, Useful Life	5 years
Trademarks and trade name | Maximum
Goodwill and Intangible Assets, Net
Finite-Lived Intangible Asset, Useful Life	7 years