Cash, Cash Equivalents and Investments - Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
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	$ 1,100,000		$ 800,000
Short-term investments, maturities, minimum	90 days
Short-term investments, maturities, maximum	1 year
Net unrealized losses	$ 49,000		21,000
China [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash in foreign bank	900,000		$ 600,000
Scenario, Forecast [Member] | Israel [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Foreign earnings repatriated		$ 200,000
Maximum [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Federal Deposit Insurance Corporation insured limit	$ 250,000