Segment Information - Property and Equipment by Geographic Region (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, Plant and Equipment, Net	$ 20,144	$ 17,473	$ 21,083
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, Plant and Equipment, Net	17,852	14,969	18,390
China
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, Plant and Equipment, Net	$ 2,292	$ 2,504	$ 2,693