Common Stock - Additional Information (Detail) - USD ($)		1 Months Ended	12 Months Ended
	Nov. 04, 2016	Jan. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Mar. 31, 2014
Class Of Stock [Line Items]
Common stock, shares authorized			50,000,000	50,000,000	50,000,000
Voting power per share			One
Common stock, dividends declared			$ 0
Proceeds from issuance of common stock in public offering, net of issuance costs	$ 59,100,000		$ 59,136,000	$ 80,209,000
Secondary Offering [Member]
Class Of Stock [Line Items]
Public offering shares of common stock issued	5,176,545	4,999,999
Proceeds from issuance of common stock in public offering, net of issuance costs	$ 59,100,000	$ 80,209,000