Employee Benefit Plans - Stock Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stock-based compensation expense	$ 3,952	$ 4,097	$ 5,298
Cost of Sales [Member]
Stock-based compensation expense	294	386	550
Research and Development Expense [Member]
Stock-based compensation expense	867	818	1,170
Selling, General and Administrative Expenses [Member]
Stock-based compensation expense	$ 2,791	$ 2,893	$ 3,578