Schedule of Net Deferred Tax Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Deferred Tax Assets And Liabilities [Line Items]
Current deferred taxes, Assets	$ 105,639	$ 109,297
Current deferred taxes, Liabilities	(1,178)	(973)
Total deferred taxes-current	104,461	108,324
Noncurrent deferred taxes, Assets	142,065	135,189
Noncurrent deferred taxes, Liabilities	(325,812)	(344,781)
Total deferred taxes-noncurrent	(183,747)	(209,592)
Net deferred income tax liabilities	$ (79,286)	$ (101,268)

Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards, net of deferred tax liability attributable to taxable temporary differences expected to be realized or consumed within one year or operating cycle, if longer.

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Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards expected to be realized or consumed within one year or operating cycle, if longer.

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Amount after allocation of valuation allowances of noncurrent deferred tax asset attributable to deductible temporary differences and carryforwards. Noncurrent assets are expected to be realized or consumed after one year (or the normal operating cycle, if longer).

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Amount of deferred tax liability attributable to taxable temporary differences, net of deferred tax asset attributable to deductible temporary differences and carryforwards net of valuation allowances expected to be realized or consumed within one year or operating cycle, if longer.

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