Income Taxes - Narrative (Details)	12 Months Ended
	Dec. 31, 2019 USD ($) ownership_change	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2011 USD ($)	Aug. 31, 2006 USD ($)
Operating Loss Carryforwards [Line Items]
Number of changes in ownership | ownership_change	3
Increase (decrease) in deferred tax asset valuation allowance	$ 33,500,000	$ (36,100,000)
Income tax expense (benefits)	0	0	$ 0
Net deferred tax liability	17,425,000	17,425,000
Less valuation allowance	151,544,000	118,064,000
Unrecognized tax benefits that, if recognized, would affect effective tax rate	0	0
Interest or penalties recorded	0	0	$ 0
Interest or penalties accrued	0	$ 0
Internal Revenue Service (IRS)
Operating Loss Carryforwards [Line Items]
Net operating losses	389,500,000
Tax credit carryforward, amount	6,000,000.0
Operating loss carryforwards decrease				$ 121,100,000	$ 1,900,000
Tax credit carryforwards, decrease				3,000,000.0
Internal Revenue Service (IRS) | Drug Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Tax credit carryforward, amount	2,000,000.0
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Tax credit carryforward, amount	4,000,000.0
Operating loss carryforwards decrease				$ 53,300,000
State and Local Jurisdiction | California
Operating Loss Carryforwards [Line Items]
Net operating losses	234,600,000
Foreign Tax Authority
Operating Loss Carryforwards [Line Items]
Net operating losses	$ 227,700,000