Cash, Cash Equivalents and Investments - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents maturities			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%		100.00%
Cash	$ 4,526,000		$ 4,526,000		$ 6,077,000
Cash equivalents	2,779,000		2,779,000		978,000
Cash and cash equivalents in foreign bank	2,000,000		2,000,000		1,300,000
Income tax expense (benefit)	5,751,000	$ 193,000	4,460,000	$ 174,000
Short-term investments	$ 21,973,000		$ 21,973,000		24,728,000
Short-term investments, maturities			90 days
Net unrealized gains (losses)			$ 2,000		$ 1,000
Percentage of investment in bond protected by bond default insurance	9.00%		9.00%		11.00%
Corporate Bonds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments	$ 6,700,000		$ 6,700,000		$ 7,600,000
U.S. Government Agency Bonds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments	5,000,000		5,000,000		7,000,000
Pre-refunded Municipal Bonds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments	7,300,000		7,300,000		7,500,000
Certificates of Deposit [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments	2,900,000		2,900,000		2,700,000
China [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash in foreign bank	1,600,000		1,600,000		$ 800,000
Israel [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Income tax expense (benefit)			100,000
Maximum [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Federal Deposit Insurance Corporation insured limit	$ 250,000		$ 250,000