Income Taxes - Additional Information (Detail) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) subsidiary	Sep. 30, 2020 USD ($)	Dec. 31, 2020 subsidiary
Income Tax Disclosure [Abstract]
Pre-tax losses	$ 1,013	$ 16,641	$ 55,059	$ 70,935
Benefit from income taxes	$ 0	$ 132	$ 0	$ 436
Percentage of annual research and development credit for cash		65.00%		65.00%
Number of foreign subsidiaries \| subsidiary			0		0

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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+ Details

- Definition

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

+ References + Details