Description of Business - Additional Information (Detail) $ / shares in Units, $ in Thousands		12 Months Ended
	Jun. 18, 2014 USD ($) $ / shares shares	Dec. 31, 2016 Subsidiary	Dec. 31, 2014 USD ($)
Basis Of Presentation [Line Items]
Number of Subsidiaries | Subsidiary		3
Proceeds from initial public offering			$ 74,712
Convertible Preferred Stock [Member]
Basis Of Presentation [Line Items]
Common shares issued upon conversion of securities | shares	115,982
Convertible Debt Securities [Member]
Basis Of Presentation [Line Items]
Common shares issued upon conversion of securities | shares	15,319,034
IPO [Member]
Basis Of Presentation [Line Items]
Initial public offering, common stock shares | shares	7,500,000
Initial public offering, common stock price per share | $ / shares	$ 11.00
Proceeds from initial public offering	$ 74,700
Underwriting discounts and commissions	4,300
Other offering expenses	$ 3,500