Stock-Based Compensation (Stock-Based Compensation Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Schedule of stock-based compensation expense
Stock-based compensation	$ 1,251	$ 1,346	$ 2,536	$ 2,575
Stock options [Member]
Schedule of stock-based compensation expense
Stock-based compensation	269	320	517	596
Restricted stock units [Member]
Schedule of stock-based compensation expense
Stock-based compensation	662	792	1,454	1,661
Performance stock units [Member]
Schedule of stock-based compensation expense
Stock-based compensation	320	234	565	318
Research and development [Member]
Schedule of stock-based compensation expense
Stock-based compensation	238	268	529	507
Selling, general and administrative [Member]
Schedule of stock-based compensation expense
Stock-based compensation	$ 1,013	$ 1,078	$ 2,007	$ 2,068