Income Taxes, Reconciliation of Effective Tax Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation Between Effective and Statutory Tax Rate [Abstract]
Pre-tax loss	$ (83,622)	$ (87,906)	$ (54,391)
Statutory rate	(29,268)	(30,767)	(19,035)
State income tax net of federal benefit	(276)	1	(3,125)
Net change in valuation allowance	55,927	69,499	29,547
Loss on debt extinguishment	0	0	2,406
Tax credits	(26,954)	(41,284)	(23,628)
California franchise tax refund	0	0	(2,795)
Deferred tax true-up	2,591	1,496	977
Other	914	1,427	246
Income tax expense (benefit)	$ 2,934	$ 372	$ (15,407)
Reconciliation Between Effective and Statutory Tax Rate Percentage [Abstract]
Statutory rate	35.00%	35.00%	35.00%
State income tax net of federal benefit	0.30%	0.00%	5.70%
Net change in valuation allowance	(66.90%)	(79.10%)	(54.30%)
Loss on debt extinguishment	0.00%	0.00%	(4.40%)
Tax credits	32.20%	47.00%	43.40%
California franchise tax refund	0.00%	0.00%	5.10%
Deferred tax true-up	(3.10%)	(1.70%)	(1.80%)
Other	(1.10%)	(1.60%)	(0.50%)
Effective rate	(3.50%)	(0.40%)	28.20%