Segment Reporting - Revenues (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
Revenue	$ 46,309	$ 51,381	$ 48,363	$ 54,528	$ 61,030	$ 63,250	$ 56,150	$ 69,470	$ 200,581	$ 249,900	$ 223,146
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									149,031	171,759	132,447
Americas, excluding the United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									9,127	11,538	9,705
EMEA
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									24,303	36,134	43,507
APAC
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									$ 18,120	$ 30,469	$ 37,487