Geographic Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 56,656	$ 53,889	$ 157,174	$ 167,775
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	50,641	48,125	139,326	149,436
Americas, excluding U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	773	688	2,258	1,991
Europe, Middle East, India, Africa
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	3,444	3,223	10,280	11,122
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 1,798	$ 1,853	$ 5,310	$ 5,226