Derivatives, Hedges, Financial Instruments and Carbon Credits - Net Gains (Losses) Included in Continuing Operating Results and Statement of Operations Classifications (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Total net gain (losses) included in operating results	$ (291)	$ (2,513)
Cost of Sales [Member] | Commodities Contracts [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total net gain (losses) included in operating results		(17)
Cost of Sales [Member] | Foreign Exchange Contracts [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total net gain (losses) included in operating results		13
Other Income [Member] | Carbon Credits [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total net gain (losses) included in operating results	867	60
Other Expense [Member] | Contractual Obligations Relating to Carbon Credits [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total net gain (losses) included in operating results	(867)	(60)
Non-operating Other Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Non-operating other expense - embedded derivative	$ (291)	$ (2,509)