Derivative Financial Instruments - Fair Values of Outstanding Zero Cost Collar Recorded as Liabilities (Detail) - Zero Cost Collars [Member] - USD ($)
$ in Thousands
Sep. 30, 2016
Dec. 31, 2015
Liability Derivatives:    
Derivatives designated as hedging instruments, Liability $ 123 $ 40
Other Current Liabilities [Member]    
Liability Derivatives:    
Derivatives designated as hedging instruments, Liability $ 123 $ 40