Cash, Cash Equivalents and Investments - Additional Information (Detail) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents maturities	90 days	90 days
Investment of cash equivalents are redeemable upon demand using amortized cost method	$ 1.00
Investment in money market funds restricted by investment in short term securities, percentage	100.00%
Cash and cash equivalents in foreign bank	$ 3,200,000	$ 2,900,000
Short-term investments, maturities, minimum	90 days
Short-term investments, maturities, maximum	1 year
Long-term investments, maturities, minimum	1 year
Long-term investments, maturities, maximum	2 years
Unrealized losses	$ (2,000)	(8,000)
Realized gains (losses)	(2,000)
CHINA
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents in foreign bank	2,300,000	$ 2,900,000
CHINA | Cash Equivalents [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents in foreign bank	$ 1,100,000
Maturity period of cash deposit	90 days
CHINA | Cash [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents in foreign bank	$ 1,200,000
Sweden
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents in foreign bank	900,000
France
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents in foreign bank	900,000
Maximum [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Federal Deposit Insurance Corporation insured limit	$ 250,000