Equity - Controlled Equity Offering Sales Agreement - Additional Information (Detail) - Cantor Fitzgerald & Co. [Member] - Controlled Equity Offering Sales Agreement [Member] - USD ($)		1 Months Ended	3 Months Ended
	May 01, 2017	Apr. 30, 2017	Mar. 31, 2017	Nov. 07, 2016	Dec. 07, 2015
Common Stock [Member]
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award Options [Line Items]
Issuance of common stock, net of issuance costs			0
Subsequent Event [Member] | Common Stock [Member]
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award Options [Line Items]
Issuance of common stock, net of issuance costs	7,042,413	1,276,017
Net proceeds from sale of common stock	$ 66,500,000	$ 14,500,000
Maximum [Member]
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award Options [Line Items]
Aggregate offering price				$ 50,000,000	$ 50,000,000
Percentage of commission of gross proceeds from the sale of Shares			3.00%