Income Taxes (Schedule Of Deferred Tax Assets And Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Employee benefits	$ 96,420	$ 91,474
Self-insurance accruals	26,296	23,042
Domestic operating-loss carryforwards	6,156	22,461
Foreign operating-loss carryforwards	16,723	16,832
Tax-credit carryforwards	10,785us-gaap_TaxCreditCarryforwardAmount	10,019us-gaap_TaxCreditCarryforwardAmount
Share-based compensation	15,171	16,551
Other	11,204us-gaap_DeferredTaxAssetsOther	11,471us-gaap_DeferredTaxAssetsOther
Valuation allowance	(26,019)	(25,358)
Total deferred income tax assets	156,736us-gaap_DeferredTaxAssetsNet	166,492us-gaap_DeferredTaxAssetsNet
Property, plant and equipment	351,684	348,728
Prepaid expenses	21,789	24,401
Revenue	6,624	9,013
Other	5,471us-gaap_DeferredTaxLiabilitiesOther	6,967us-gaap_DeferredTaxLiabilitiesOther
Total deferred income tax liabilities	385,568us-gaap_DeferredTaxLiabilities	389,109us-gaap_DeferredTaxLiabilities
Net deferred tax liability	$ (228,832)us-gaap_DeferredTaxAssetsLiabilitiesNet	$ (222,617)us-gaap_DeferredTaxAssetsLiabilitiesNet

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.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible domestic operating loss carryforwards. Excludes state and local operating loss carryforwards.

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The tax effect as of the balance sheet date of the amount of the estimated future tax deductions arising from employee benefit costs not otherwise specified in the taxonomy, which can only be deducted for tax purposes when actual costs are incurred, and which can only be realized if sufficient tax-basis income is generated in future periods to enable the deduction to be taken.

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

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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 not separately disclosed.

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Amount of deferred tax consequences attributable to taxable temporary differences derived from prepaid expenses.

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

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The amount of the tax credit carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

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