Income Taxes Tax Reconciliation (Details) (USD $) In Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Income Tax Disclosure [Abstract]
Income Before Income Taxes	$ 15,530	$ 19,108	$ 67,737	$ 72,818
Income tax calculated at 35% Federal statutory rate	(5,435)	(6,687)	(23,707)	(25,485)
Permanents or flow through adjustments:
Flow through repair deduction	3,243	2,341	8,745	6,902
Flow through of state bonus depreciation deduction	1,170	0	4,452	0
Recognition of state NOL benefit/Valuation allowance release	0	0	2,402	2,178
State income tax & other, net	387	(383)	(1,189)	(1,625)
Total adjustments	4,800	1,958	14,410	7,455
Income tax expense	$ (635)	$ (4,729)	$ (9,297)	$ (18,030)

Effective Income Tax Rate Reconciliation Permanent Or Flow Through Adjutsments [Abstract]

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Income Tax Reconciliation, Accelerated Tax Depreciation, Flow Through Adjustment

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Income Tax Reconciliation, Deductions, Repair Costs, Flow Through Adjustment

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Sum of operating profit and nonoperating income or expense before Income or Loss from equity method investments, income taxes, extraordinary items, and noncontrolling interest.

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The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to continuing operations.

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The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

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The portion of the difference, between total income tax expense or benefit as reported in the Income Statement for the period and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations, that is attributable to state and local income tax expense or benefit.

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