Income Taxes, Reconciliation of Effective Tax Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation Between Effective and Statutory Tax Rate [Abstract]
Pre tax loss	$ (87,906)	$ (54,391)	$ (66,558)
Statutory rate	(30,767)	(19,035)	(23,295)
State income tax net of federal benefit	1	(3,125)	(3,823)
Net change in valuation allowance	69,499	29,547	28,850
Loss on debt extinguishment	0	2,406	0
Tax credits	(41,284)	(23,628)	(15,839)
California franchise tax refund	0	(2,795)	0
Deferred tax true-up	1,496	977	8,023
Other	1,427	246	170
Income tax expense (benefit)	$ 372	$ (15,407)	$ (5,914)
Reconciliation Between Effective and Statutory Tax Rate Percentage [Abstract]
Statutory rate	35.00%	35.00%	35.00%
State income tax net of federal benefit	0.00%	5.70%	5.70%
Net change in valuation allowance	(79.10%)	(54.30%)	(43.30%)
Loss on debt extinguishment	0.00%	(4.40%)	0.00%
Tax credits	47.00%	43.40%	23.80%
California franchise tax refund	0.00%	5.10%	0.00%
Deferred tax true-up	(1.70%)	(1.80%)	(12.10%)
Other	(1.60%)	(0.50%)	(0.20%)
Effective rate	(0.40%)	28.20%	8.90%