Segment Reporting and Significant Customer Information - Revenue for Individual Countries that Exceed 10% of Total Revenue (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Revenue, Major Customer [Line Items]
Total revenues	$ 36,492	$ 40,195
United States
Revenue, Major Customer [Line Items]
Total revenues	23,431	24,740
United Kingdom
Revenue, Major Customer [Line Items]
Total revenues	7,871	9,212
Rest of the world
Revenue, Major Customer [Line Items]
Total revenues	$ 5,190	$ 6,243