Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Jun. 18, 2014	Dec. 31, 2014	Dec. 31, 2016	Dec. 31, 2015
Stockholder Equity [Line Items]
Proceeds from initial public offering		$ 74,712
Total number of shares authorized			130,000,000	130,000,000
Common stock, shares authorized			125,000,000	125,000,000
Preferred stock, shares authorized			5,000,000	5,000,000
Convertible Preferred Stock [Member]
Stockholder Equity [Line Items]
Common shares issued upon conversion of securities	115,982
Convertible Debt Securities [Member]
Stockholder Equity [Line Items]
Common shares issued upon conversion of securities	15,319,034
IPO [Member]
Stockholder Equity [Line Items]
Initial public offering, common stock shares	7,500,000
Initial public offering, common stock price per share	$ 11.00
Proceeds from initial public offering	$ 74,700
Underwriting discounts and commissions	4,300
Other offering expenses	$ 3,500