Income tax disclosure.

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Operating loss carryforward, expiration year.

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- Definition

Tax credit carryforward, expiration year.

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- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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- Definition

Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

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- Definition

The amount of the tax credit carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

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- Definition

Amount of unrecognized tax benefits.

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Amount of expense for penalties related to a tax position claimed or expected to be claimed in the tax return.

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Amount of interest expense for an underpayment of income taxes.

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The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

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Amount of increase (decrease) in the valuation allowance for a specified deferred tax asset.

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Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Line Items]
Income tax expense	$ 0	$ 0	$ 0
Increase (decrease) in valuation allowance	22,300,000	40,400,000
Unrecognized tax benefits	10,322,000	$ 1,229,000
Unrecognized tax benefits would affect the effective tax rate	0
Interest related to unrecognized tax benefits	0
Penalties related to unrecognized tax benefits	0
Federal
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 887,300,000
Federal \| Minimum
Income Tax Disclosure [Line Items]
Net operating loss carryforwards, expiration year	2020
Federal \| Research And Development Tax Credits
Income Tax Disclosure [Line Items]
Tax credit carryforward amount	$ 21,700,000
Federal \| Research And Development Tax Credits \| Minimum
Income Tax Disclosure [Line Items]
Tax credit carryforward amount, expiration year	2020
Federal \| Research And Development Tax Credits \| Maximum
Income Tax Disclosure [Line Items]
Tax credit carryforward amount, expiration year	2039
California and Other States
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 318,300,000
California and Other States \| Minimum
Income Tax Disclosure [Line Items]
Net operating loss carryforwards, expiration year	2020
California and Other States \| Maximum
Income Tax Disclosure [Line Items]
Net operating loss carryforwards, expiration year	2039
California State \| Research And Development Tax Credits
Income Tax Disclosure [Line Items]
Tax credit carryforward amount	$ 19,600,000
Foreign
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 9,000,000.0