Equity - Common Stock - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended			12 Months Ended
	Sep. 30, 2016	Aug. 31, 2016	May 31, 2014	Dec. 31, 2016
Stockholders Equity Note [Line Items]
Convertible senior notes, principal amount				$ 128,115
Net proceeds from public offering				64,613
American Depositary Shares
Stockholders Equity Note [Line Items]
Over allotment option, exercisable period		30 days
Sale of stock price per share		$ 2.679
Net proceeds from public offering		$ 64,600
American Depositary Shares | IPO
Stockholders Equity Note [Line Items]
Issuance of stock (shares)		21,100,000
American Depositary Shares | Over-Allotment Option
Stockholders Equity Note [Line Items]
Issuance of stock (shares)		3,165,000
Convertible Debt
Stockholders Equity Note [Line Items]
Convertible senior notes, principal amount				$ 150,000
Convertible Debt | American Depositary Shares
Stockholders Equity Note [Line Items]
Exchange of exchangeable senior notes, net of transaction costs (shares)				60,311,188
Convertible Debt | 2014 Notes
Stockholders Equity Note [Line Items]
Convertible senior notes, principal amount	$ 118,700		$ 118,700
Convertible Debt | 2014 Notes | American Depositary Shares
Stockholders Equity Note [Line Items]
Exchange of exchangeable senior notes, net of transaction costs (shares)	47,739,925
Convertible Debt | 2015 Notes
Stockholders Equity Note [Line Items]
Convertible senior notes, principal amount	$ 31,300
Convertible Debt | 2015 Notes | American Depositary Shares
Stockholders Equity Note [Line Items]
Exchange of exchangeable senior notes, net of transaction costs (shares)	12,571,263