Income Taxes - Components of Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Current:
State	$ 4	$ 2	$ 2
Foreign	0	0	301
Total current	4	2	303
Deferred:
Federal	0	0	0
Total deferred	0	0	0
Provision for income taxes	$ 4	$ 2	$ 303

Amount of current foreign income tax expense (benefit) pertaining to income (loss) from continuing operations.

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Amount of current income tax expense (benefit) pertaining to taxable income (loss) from continuing operations.

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Amount of current state and local tax expense (benefit) pertaining to income (loss) from continuing operations.

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Amount of deferred federal income tax expense (benefit) pertaining to income (loss) from continuing operations.

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