Financial Instruments - Additional Information (Detail) (USD $)	3 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2013
Derivative [Line Items]
Amount of losses, net of income taxes, reclassified to earnings from change in fair value of derivatives component of accumulated other comprehensive loss	$ 1,100,000	$ 2,800,000
Estimated reclassification of losses, net of income taxes, from the change in fair value of derivatives component of accumulated other comprehensive loss to earnings during the next twelve months		3,800,000
Interest Rate Swap and Natural Gas Swap Agreements
Derivative [Line Items]
Derivative liabilities	8,500,000	8,500,000
Interest rate swap agreements
Derivative [Line Items]
Aggregate notional principal amount of outstanding interest rate swap agreements	291,600,000	291,600,000
Net payments under derivative swap agreements	1,600,000	4,400,000
Foreign Currency Exchange Rate Risk
Derivative [Line Items]
Foreign currency (losses) gains of net investment hedges included in accumulated other comprehensive (loss) income	(10,000,000)	(5,300,000)
Accrued liabilities | Interest Rate Swap and Natural Gas Swap Agreements
Derivative [Line Items]
Derivative liabilities	6,600,000	6,600,000
Other liabilities | Interest Rate Swap and Natural Gas Swap Agreements
Derivative [Line Items]
Derivative liabilities	1,900,000	1,900,000
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Derivative [Line Items]
Cash and cash equivalents	134,473,000	134,473,000
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Interest rate swap agreements
Derivative [Line Items]
Derivative liabilities	8,187,000	8,187,000
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Natural gas swap agreements
Derivative [Line Items]
Derivative liabilities	272,000	272,000
Estimate of Fair Value, Fair Value Disclosure [Member]
Derivative [Line Items]
Cash and cash equivalents	134,473,000	134,473,000
Estimate of Fair Value, Fair Value Disclosure [Member] | Interest rate swap agreements
Derivative [Line Items]
Derivative liabilities	8,187,000	8,187,000
Estimate of Fair Value, Fair Value Disclosure [Member] | Natural gas swap agreements
Derivative [Line Items]
Derivative liabilities	272,000	272,000
Bank Debt | Carrying (Reported) Amount, Fair Value Disclosure [Member]
Derivative [Line Items]
Long-Term Debt	999,928,000	999,928,000
Bank Debt | Estimate of Fair Value, Fair Value Disclosure [Member]
Derivative [Line Items]
Long-Term Debt	999,928,000	999,928,000
5% Senior Notes
Derivative [Line Items]
Senior note interest rate	5.00%	5.00%
5% Senior Notes | Carrying (Reported) Amount, Fair Value Disclosure [Member]
Derivative [Line Items]
Long-Term Debt	500,000,000	500,000,000
5% Senior Notes | Estimate of Fair Value, Fair Value Disclosure [Member]
Derivative [Line Items]
Long-Term Debt	498,700,000	498,700,000
Senior Notes Five and One Half Percent [Member] [Member]
Derivative [Line Items]
Senior note interest rate	5.50%	5.50%
Senior Notes Five and One Half Percent [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member]
Derivative [Line Items]
Long-Term Debt	300,000,000	300,000,000
Senior Notes Five and One Half Percent [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Derivative [Line Items]
Long-Term Debt	$ 292,314,000	$ 292,314,000
Natural Gas Commodity [Member] | Natural gas swap agreements
Derivative [Line Items]
Aggregate notional principal amount of natural gas swap agreements in MMBtu	457,000	457,000
Percentage of hedged estimated twelve month exposure to fluctuations in natural gas prices	9.00%	9.00%
Natural Gas Commodity [Member] | Natural gas swap agreements | Minimum
Derivative [Line Items]
Underlying, Derivative, price per MMBtu	3.695
Natural Gas Commodity [Member] | Natural gas swap agreements | Maximum
Derivative [Line Items]
Underlying, Derivative, price per MMBtu	4.548