Income Taxes - Net Deferred Income Tax Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Current deferred income taxes:
Assets	$ 58,272us-gaap_DeferredTaxAssetsNetCurrent	$ 61,263us-gaap_DeferredTaxAssetsNetCurrent
Liabilities	(31,014)us-gaap_DeferredTaxLiabilitiesCurrent	(16,424)us-gaap_DeferredTaxLiabilitiesCurrent
Net current deferred income taxes	27,258	44,839
Non-current deferred income taxes:
Assets	3,402us-gaap_DeferredTaxAssetsNetNoncurrent
Liabilities	(300,516)	(244,256)
Net non-current deferred income taxes	(297,114)	(244,256)
Total net deferred income tax liabilities	$ (269,856)us-gaap_DeferredTaxLiabilities	$ (199,417)us-gaap_DeferredTaxLiabilities

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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 after valuation allowances.

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Gross amount of noncurrent deferred tax liabilities, which result from applying the applicable tax rate to taxable temporary differences pertaining to each jurisdiction to which the entity is obligated to pay income tax.

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