Derivative Financial Instruments - Fair Values of Outstanding Zero Cost Collar Recorded as Liabilities (Detail) - Zero cost collars [Member] $ in Thousands	Jun. 30, 2015 USD ($)
Liability Derivatives:
Derivatives designated as hedging instruments, Liability	$ 1,702
Other current liabilities [Member]
Liability Derivatives:
Derivatives designated as hedging instruments, Liability	$ 1,702