Basis of Presentation and Summary of Significant Accounting Policies (Accounting for Share-Based Compensation) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Basis of Presentation [Line Items]
Share-based compensation expense total	$ 4,624	$ 4,647	$ 10,669	$ 8,766
Research and development expenses
Basis of Presentation [Line Items]
Share-based compensation expense total	1,928	2,089	5,867	3,674
General and administrative expenses
Basis of Presentation [Line Items]
Share-based compensation expense total	$ 2,696	$ 2,558	$ 4,802	$ 5,092