Fair Value of Financial Instruments - Schedule of Estimated Fair Values of Financial Instruments Outstanding (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Cost		$ 6,353
Unrealized Gains		0
Unrealized Losses		0
Fair Value		6,353
Cash and Cash Equivalents
Debt Securities, Available-for-sale [Line Items]
Cost	$ 5,889	6,053
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	$ 5,889	6,053
Short-term investments
Debt Securities, Available-for-sale [Line Items]
Cost		300
Unrealized Gains		0
Unrealized Losses		0
Fair Value		$ 300

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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