Income Taxes - Reconciliation Between Effective and Income Tax Rate (Detail)	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Federal income tax rate	21.00%	21.00%
Research and development tax credits	14.00%	6.00%
Non-deductible executive compensation	(2.00%)	(1.00%)
Valuation allowance	(31.00%)	(12.00%)
Expired tax attribute carryforwards	0.00%	(17.00%)
Gain on foreign entity liquidation	1.00%	3.00%
Foreign currency gains and losses	1.00%	2.00%
Unrecognized tax benefits	(3.00%)	0.00%
Other	(1.00%)	(2.00%)
Net effective tax rate	0.00%	0.00%

Effective Income Tax Rate Reconciliation, Expired Tax Attribute Carryforwards, Percent

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Effective Income Tax Rate Reconciliation, Gains (Losses) On Foreign Exchange

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Effective income tax rate reconciliation nondeductible expense executive compensation.

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

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to changes in the valuation allowance for deferred tax assets.

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to disposition of a business not qualifying as a discontinued operation.

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to income tax contingencies. Includes, but not limited to, domestic tax contingency, foreign tax contingency, state and local tax contingency, and other contingencies.

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