Income Taxes - Deferred Tax Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Deferred income tax liabilities -
Property and equipment	$ (255,084)	$ (218,739)
Goodwill	(72,030)	(58,643)
Other intangibles	(53,599)	(42,604)
Book/tax accounting method difference	(63,989)us-gaap_DeferredTaxLiabilitiesOther	(50,764)us-gaap_DeferredTaxLiabilitiesOther
Total deferred income tax liabilities	(444,702)us-gaap_DeferredIncomeTaxLiabilities	(370,750)us-gaap_DeferredIncomeTaxLiabilities
Deferred income tax assets -
Accruals and reserves	22,885	22,642
Accrued insurance	64,773	59,640
Deferred revenue	16,575us-gaap_DeferredTaxAssetsDeferredIncome	15,336us-gaap_DeferredTaxAssetsDeferredIncome
Stock and incentive compensation and pension withdrawal liabilities	53,610	57,674
Net operating loss carryforwards	21,511	20,828
Other	10,678us-gaap_DeferredTaxAssetsOther	10,857us-gaap_DeferredTaxAssetsOther
Subtotal	190,032us-gaap_DeferredTaxAssetsGross	186,977us-gaap_DeferredTaxAssetsGross
Valuation allowance	(15,186)	(15,644)	(9,300)
Total deferred income tax assets	174,846us-gaap_DeferredTaxAssetsNet	171,333us-gaap_DeferredTaxAssetsNet
Total net deferred income tax liabilities	$ (269,856)us-gaap_DeferredTaxLiabilities	$ (199,417)us-gaap_DeferredTaxLiabilities

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Amount of deferred tax liability attributable to taxable temporary differences.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from deferred income.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

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Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences not separately disclosed.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from employee compensation.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from reserves and accruals.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from estimated losses under self insurance.

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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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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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Amount of deferred tax liability attributable to taxable temporary differences from goodwill.

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Amount of deferred tax liability attributable to taxable temporary differences from intangible assets other than goodwill.

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Amount of deferred tax liability attributable to taxable temporary differences not separately disclosed.

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Amount of deferred tax liability attributable to taxable temporary differences from property, plant, and equipment.

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