Income Taxes Components of Deferred Income Tax Amounts (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Deferred Income Tax Assets
Provision for bad debts	$ 9,210	$ 8,012
Deferred compensation and other benefit obligations	83,065	72,227
Workers' compensation	9,138	9,538
Stock-based compensation	14,572	12,067
Credits and net operating loss carryforwards	39,309	49,556
Other	25,316us-gaap_DeferredTaxAssetsOther	25,953us-gaap_DeferredTaxAssetsOther
Total deferred income tax assets	180,610us-gaap_DeferredTaxAssetsNet	177,353us-gaap_DeferredTaxAssetsNet
Deferred Income Tax Liabilities
Amortization of intangible assets	(25,060)	(23,305)
Property and equipment basis differences	(12,384)	(8,098)
Other	(7,261)us-gaap_DeferredTaxLiabilitiesOther	(6,626)us-gaap_DeferredTaxLiabilitiesOther
Total deferred income tax liabilities	(44,705)us-gaap_DeferredTaxLiabilities	(38,029)us-gaap_DeferredTaxLiabilities
Valuation allowance	(29,561)	(37,044)
Total deferred income tax assets, net	$ 106,344us-gaap_DeferredTaxAssetsLiabilitiesNet	$ 102,280us-gaap_DeferredTaxAssetsLiabilitiesNet

Deferred tax assets operating loss and tax credit carryforwards

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from the provision for loan losses.

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

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