Segments and Geographic Information (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) segment	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of operating segments | segment									1
Number of reportable segments | segment									1
Revenues	$ 44,184	$ 45,355	$ 44,635	$ 45,388	$ 47,339	$ 46,181	$ 47,969	$ 48,138	$ 179,561	$ 189,628	$ 200,273
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									173,852	185,741	194,886
International
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									$ 5,709	$ 3,887	$ 5,387