Segment Reporting and Significant Customer Information - Revenue for Individual Countries that Exceed 10% of Total Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Revenue, Major Customer [Line Items]
Total revenues	$ 34,046	$ 36,792	$ 68,850	$ 75,937
United States
Revenue, Major Customer [Line Items]
Total revenues	20,887	22,496	41,189	45,927
United Kingdom
Revenue, Major Customer [Line Items]
Total revenues	6,547	6,856	13,668	14,727
Rest of the world
Revenue, Major Customer [Line Items]
Total revenues	$ 6,612	$ 7,440	$ 13,993	$ 15,283