Income Taxes Components of Net Deferred Income Taxes (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Deferred tax assets [Abstract]
Net operating loss carryforwards	$ 16,008,000	$ 14,577,000
Accruals and reserves not deducted for tax purposes until paid	11,027,000	19,848,000
Stock-based compensation	6,954,000	6,348,000
Deferred revenue	3,652,000us-gaap_DeferredTaxAssetsDeferredIncome	1,216,000us-gaap_DeferredTaxAssetsDeferredIncome
Deferred compensation	2,810,000	2,974,000
Nonshareholder contributions	1,871,000	2,304,000
Interest rate swaps	1,664,000	0
Alternative minimum tax credit	1,592,000	1,592,000
Postretirement benefits	425,000	811,000
Other	457,000us-gaap_DeferredTaxAssetsOther	119,000us-gaap_DeferredTaxAssetsOther
Total deferred tax assets	275,526,000us-gaap_DeferredTaxAssetsGross	273,031,000us-gaap_DeferredTaxAssetsGross
Valuation allowance	(14,793,000)	(12,194,000)
Deferred tax liabilities [Abstract]
Property basis difference	(1,088,572,000)	(1,029,492,000)
Interest rate swaps	0	(13,985,000)
Other	(1,519,000)us-gaap_DeferredTaxLiabilitiesOther	(1,884,000)us-gaap_DeferredTaxLiabilitiesOther
Net deferred tax liabilities	(829,358,000)us-gaap_DeferredTaxLiabilities	(784,524,000)us-gaap_DeferredTaxLiabilities
Track maintenance credit [Member]
Deferred tax assets [Abstract]
Tax credit carryforward	227,102,000	221,278,000
Foreign tax credit [Member]
Deferred tax assets [Abstract]
Tax credit carryforward	$ 1,964,000	$ 1,964,000

Deferred Tax Asset, Nonshareholder Contributions

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