Shareholders’ Equity (Share-based Compensation Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 3,061	$ 1,743	$ 10,343	$ 6,595
Research and development [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	891	245	3,101	794
General and administrative [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	2,170	1,498	7,242	5,801
Stock Option [Member] | Research and development [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	636	98	1,609	142
Stock Option [Member] | General and administrative [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	1,443	286	2,950	575
Restricted Stock [Member] | Research and development [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	240	147	1,452	652
Restricted Stock [Member] | General and administrative [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	545	1,212	3,719	5,226
Warrant [Member] | Research and development [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	15	0	40	0
Warrant [Member] | General and administrative [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 182	$ 0	$ 573	$ 0