Income Taxes (Details 1) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred Tax Assets and Liabilities
Deferred Tax Assets, Operating Loss Carryforwards	$ 186,967	$ 258,405
Deferred Tax Assets, Tax Credit Carryforwards, Research	46,682	44,111
Deferred Tax Assets, Tax Credit Carryforwards, Orphan Drug	26,524	24,233
Deferred Tax Assets, In Process Research and Development	69,561	86,845
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-based Compensation Cost	3,923	7,060
Deferred Tax Assets, Deferred Income	12,950	39,307
Deferred Tax Assets, Other	5,579	8,432
Deferred Tax Assets, Gross	352,186	468,393
Deferred Tax Liability Related to Acquisition of Symphony Icon	(10,896)	(18,675)
Deferred Tax Liabilities, Other	(1)	0
Deferred Tax Liabilities, Gross	(10,897)	(18,675)
Deferred Tax Assets, Valuation Allowance	(347,303)	(468,393)
Deferred Tax Liabilities, Net	$ (6,014)	$ (18,675)