Income Taxes - Narrative (Details) - USD ($)	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating Loss Carryforwards [Line Items]
Valuation allowance	$ 124,828,000	$ 118,169,000
Net operating loss carryovers	87,877,000	82,747,000
Unrecognized tax benefits	16,953,000	17,939,000	$ 16,573,000
Unrecognized tax benefits that would impact effective tax rate	13,700,000
Income tax penalties and interest accrued	0	0
Internal Revenue Service (IRS)
Operating Loss Carryforwards [Line Items]
Net operating loss carryovers		366,800,000
Internal Revenue Service (IRS) | Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Research and development tax credits carryforward		33,000,000
California
Operating Loss Carryforwards [Line Items]
Net operating loss carryovers		276,000,000
California | Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Research and development tax credits carryforward		$ 9,700,000
After 2017, No Expiration | Internal Revenue Service (IRS)
Operating Loss Carryforwards [Line Items]
Net operating loss carryovers	$ 103,400,000