Income Taxes (Details 4) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Deferred Tax Liability Not Recognized [Line Items]
Accruals and reserves not deducted for tax purposes until paid	$ 4,290	$ 6,845
Net operating loss carryforwards	1,306	1,262
Capital loss carryforward	5,251	6,367
Interest rate swaps	2,547	3,306
Nonshareholder contributions	1,622	1,998
Deferred compensation	2,473	1,963
Postretirement benefits	801	745
Share-based compensation	4,358	4,421
Foreign tax credit	1,964	1,964
Track maintenance credit	38,238	37,639
Other	87	494
Total deferred tax assets	62,937	67,004
Valuation allowance	(5,251)	(6,367)
Property basis difference	(321,365)	(297,476)
Other	(1,299)	(2,125)
Net deferred tax liabilities	$ (264,978)	$ (238,964)