Basis of Presentation (Accounting for Share-Based Compensation) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Basis of Presentation [Line Items]
Share-based compensation expense total	$ 3,760	$ 3,027	$ 6,675	$ 5,093
Research and development expenses
Basis of Presentation [Line Items]
Share-based compensation expense total	1,253	956	2,174	1,645
General and administrative expenses
Basis of Presentation [Line Items]
Share-based compensation expense total	$ 2,507	$ 2,071	$ 4,501	$ 3,448