Fair Value of Assets and Liabilities (Detail) (Fair Value, Measurements, Recurring, USD $)	Dec. 31, 2012	Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative liabilities	$ (11,426,000)	$ (42,905,000)
Commodity derivative contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets	3,043,000	197,000
Derivative liabilities	(102,000)	(489,000)
Nonqualified employee savings plans
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative liabilities	(10,293,000)	(8,030,000)
Foreign exchange derivative contract
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative liabilities	(1,031,000)	(8,459,000)
Interest rate derivative contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative liabilities		(25,927,000)
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative liabilities	(10,293,000)	(8,030,000)
Quoted Prices in Active Markets for Identical Assets (Level 1) | Commodity derivative contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Nonqualified employee savings plans
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative liabilities	(10,293,000)	(8,030,000)
Quoted Prices in Active Markets for Identical Assets (Level 1) | Foreign exchange derivative contract
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative liabilities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Interest rate derivative contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative liabilities		0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative liabilities	(1,133,000)	(34,875,000)
Significant Other Observable Inputs (Level 2) | Commodity derivative contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets	3,043,000	197,000
Derivative liabilities	(102,000)	(489,000)
Significant Other Observable Inputs (Level 2) | Nonqualified employee savings plans
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative liabilities	0	0
Significant Other Observable Inputs (Level 2) | Foreign exchange derivative contract
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative liabilities	(1,031,000)	(8,459,000)
Significant Other Observable Inputs (Level 2) | Interest rate derivative contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative liabilities		(25,927,000)
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative liabilities	0	0
Significant Unobservable Inputs (Level 3) | Commodity derivative contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Significant Unobservable Inputs (Level 3) | Nonqualified employee savings plans
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative liabilities	0	0
Significant Unobservable Inputs (Level 3) | Foreign exchange derivative contract
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative liabilities	0	0
Significant Unobservable Inputs (Level 3) | Interest rate derivative contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative liabilities		$ 0