Income Taxes (Deferred Tax Liabilities and Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax liabilities:
Depreciation	$ (16,585)	$ (51,717)
Deferred profit (for tax purposes) on sale to finance subsidiary	(43,057)	(26,765)
Lease revenue and related depreciation	(205,773)	(216,282)
Intangible assets	(60,420)	(65,916)
Operating lease liability	(76,910)	(73,403)
Basis adjustment in subsidiary	(51,548)	0
Other	(19,690)	(27,366)
Gross deferred tax liabilities	(473,983)	(461,449)
Deferred tax assets:
Postretirement medical benefits	23,472	24,892
Pension	15,042	9,640
Operating lease asset	83,696	78,765
Long-term incentives	11,814	12,946
Net operating and capital losses	182,482	130,640
Tax credit carry forwards	65,095	66,256
Section 163j carryforward	47,802	23,917
Tax uncertainties gross-up	4,904	4,982
Other	48,537	50,345
Gross deferred tax assets	482,844	402,383
Less: Valuation allowance	(159,342)	(157,450)
Net deferred tax assets	323,502	244,933
Total deferred taxes, net	$ (150,481)	$ (216,516)