Equity Investment - Additional Information (Detail) - USD ($) shares in Millions	1 Months Ended		3 Months Ended		6 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Loss from equity method investments					$ 377,000	$ 141,000
PACT Pharma
Schedule of Equity Method Investments [Line Items]
Loss from equity method investments			$ 200,000	$ 70,000	$ 400,000	100,000
Equity method investment agreement termination date					May 31, 2018
Gain in interest and other income			1,200,000
Equity method investments impairment					$ 0	$ 0
PACT Pharma | Variable interest entity
Schedule of Equity Method Investments [Line Items]
Receivable from PACT Pharma			$ 200,000		$ 200,000		$ 25,000
PACT Pharma | Series A Preferred Stock
Schedule of Equity Method Investments [Line Items]
Purchase of common stock, shares	1.0
Purchase of common stock, value	$ 1,000,000
PACT Pharma | Common Stock
Schedule of Equity Method Investments [Line Items]
Purchase of common stock, shares		3.6