Marketable Equity Investments - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended
	Apr. 30, 2015	Mar. 31, 2017
Investment [Line Items]
Carrying value of investment		$ 0
Gain on sale of investment in marketable equity securities		$ 18,000
Aduro
Investment [Line Items]
Preferred shares converted to common stock	396,700
Sale of common stock in marketable equity investment		1,600
Gain on sale of investment in marketable equity securities		$ 20,000
Common stock, shares outstanding		345,100