Income Taxes (Components of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax liabilities:
Property, plant and equipment and Rail Group assets leased to others	$ (168,345)	$ (129,876)
Equity method investments	(24,732)	(31,223)
Other	(7,999)	(8,754)
Deferred tax liabilities	(201,076)	(169,853)
Deferred tax assets:
Employee benefits	13,161	15,229
Accounts and notes receivable	2,069	2,317
Inventory	7,595	6,100
Federal income tax credits	13,075	10,225
Net operating loss carryforwards	12,766	5,753
Deferred interest (a)	6,476	0
Lease liability	8,473	0
Other	8,839	9,674
Total deferred tax assets	72,454	49,298
Valuation allowance	(1,185)	(1,024)
Net deferred tax assets	71,269	48,274
Net deferred tax liabilities	$ (129,807)	$ (121,579)