Income Taxes, Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred Tax Assets [Abstract]
Net operating loss carryovers	$ 89,717	$ 20,191	$ 89,717
R&D credits	313,652	210,455	313,652
Deferred revenue	27,381	127,763	27,381
Stock-based compensation	61,027	65,703	61,027
Intangible and capital assets	49,007	77,861	49,007
Other	8,275	12,510	8,275
Total deferred tax assets	549,059	514,483	549,059
Deferred Tax Liabilities [Abstract]
Convertible debt	(24,018)	(6,110)	(24,018)
Fixed assets	0	(1,958)	0
Other	0	(3,884)	0
Net deferred tax asset	525,041	502,531	525,041
Valuation allowance	(234,245)	(196,974)	(234,245)
Total net deferred tax assets and liabilities	290,796	305,557	290,796
One-time non-cash tax benefit related to reversal of valuation allowance	$ 332,100	(37,765)	$ (277,924)	$ (86,296)
Decrease in valuation allowance		(37,300)
Decrease in combined state tax liability		$ (59,100)