Stock-Based Compensation (Stock-Based Compensation Expense) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Schedule of stock-based compensation expense
Stock-based compensation	$ 1,229	$ 1,472
Research and development [Member]
Schedule of stock-based compensation expense
Stock-based compensation	239	527
Selling, general and administrative [Member]
Schedule of stock-based compensation expense
Stock-based compensation	990	945
Stock options [Member]
Schedule of stock-based compensation expense
Stock-based compensation	276	610
Restricted stock units [Member]
Schedule of stock-based compensation expense
Stock-based compensation	869	734
Performance stock units [Member]
Schedule of stock-based compensation expense
Stock-based compensation	$ 84	$ 128