Income Taxes (Deferred Tax Assets (Liabilities)) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Net operating losses U.S.	$ 286,619	$ 203,284
Net operating losses foreign	9,011	8,360
Research tax credits	23,260	16,491
Deferred revenue	10,121	922
Original discount interest	12,445	0
Other	17,981	11,981
Total deferred tax assets	359,437	241,038
Intangibles	(2,090)	(2,415)
Other	(2,817)	(1,767)
Total deferred tax liabilities	(4,907)	(4,182)
Net deferred tax assets	354,530	236,856
Less valuation allowance	(354,530)	(236,856)
Deferred tax assets, net	$ 0	$ 0