Derivatives, Hedges, Financial Instruments and Carbon Credits - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Liabilities - Current and noncurrent accrued and other liabilities:
Embedded derivative	$ (5,817)	$ (3,308)
Foreign Exchange Contracts [Member]
Assets - Supplies, prepaid items and other:
Foreign exchange contracts	7
Foreign Exchange Contracts [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets - Supplies, prepaid items and other:
Foreign exchange contracts	7
Recurring [Member]
Assets - Supplies, prepaid items and other:
Total	1,541	1,349
Liabilities - Current and noncurrent accrued and other liabilities:
Embedded derivative	(5,817)	(3,308)
Total	(7,351)	(4,796)
Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets - Supplies, prepaid items and other:
Total	327
Liabilities - Current and noncurrent accrued and other liabilities:
Embedded derivative	(5,817)
Total	(6,137)
Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets - Supplies, prepaid items and other:
Total	1,214
Liabilities - Current and noncurrent accrued and other liabilities:
Total	(1,214)
Recurring [Member] | Commodities Contracts [Member]
Assets - Supplies, prepaid items and other:
Commodities contracts	320	195
Liabilities - Current and noncurrent accrued and other liabilities:
Derivative Financial Instruments, Liabilities	(320)	(202)
Recurring [Member] | Commodities Contracts [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets - Supplies, prepaid items and other:
Commodities contracts	320
Liabilities - Current and noncurrent accrued and other liabilities:
Derivative Financial Instruments, Liabilities	(320)
Recurring [Member] | Carbon Credits [Member]
Assets - Supplies, prepaid items and other:
Carbon credits	1,214	1,154
Liabilities - Current and noncurrent accrued and other liabilities:
Contractual obligations - carbon credits	(1,214)	(1,154)
Recurring [Member] | Carbon Credits [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets - Supplies, prepaid items and other:
Carbon credits	1,214
Liabilities - Current and noncurrent accrued and other liabilities:
Contractual obligations - carbon credits	$ (1,214)
Recurring [Member] | Foreign Exchange Contracts [Member]
Liabilities - Current and noncurrent accrued and other liabilities:
Derivative Financial Instruments, Liabilities		(6)
Recurring [Member] | Interest Rate Contracts [Member]
Liabilities - Current and noncurrent accrued and other liabilities:
Derivative Financial Instruments, Liabilities		$ (126)