Stock-Based Compensation (Stock-Based Compensation Expense) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Schedule of stock-based compensation expense
Stock-based compensation	$ 1,346	$ 1,262	$ 2,575	$ 2,735
Stock options [Member]
Schedule of stock-based compensation expense
Stock-based compensation	320	531	596	1,141
Restricted stock units [Member]
Schedule of stock-based compensation expense
Stock-based compensation	792	604	1,661	1,296
Performance stock units [Member]
Schedule of stock-based compensation expense
Stock-based compensation	234	127	318	298
Research and development [Member]
Schedule of stock-based compensation expense
Stock-based compensation	268	502	507	1,706
Selling, general and administrative [Member]
Schedule of stock-based compensation expense
Stock-based compensation	$ 1,078	$ 760	$ 2,068	$ 1,029