Stock-Based Compensation (Stock-Based Compensation Expense) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Schedule of stock-based compensation expense
Stock-based compensation	$ 1,669	$ 1,389
Stock options [Member]
Schedule of stock-based compensation expense
Stock-based compensation	334	304
RSAs and RSUs [Member]
Schedule of stock-based compensation expense
Stock-based compensation	459	574
Performance stock units [Member]
Schedule of stock-based compensation expense
Stock-based compensation	641	511
Performance Based Options (PBOs) [Member]
Schedule of stock-based compensation expense
Stock-based compensation	235	0
Research and development [Member]
Schedule of stock-based compensation expense
Stock-based compensation	323	220
Selling, General and Administrative Expenses [Member]
Schedule of stock-based compensation expense
Stock-based compensation	$ 1,346	$ 1,169