Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Deferred income tax assets:
Lease and rents	$ 5,563	$ 5,742
Inventory	99	80
Employee benefits	193	238
Bad debts and other allowances	489	395
Net operating loss and capital loss carryforwards	416	568
Deferred income	78	43
Insurance reserves	501	489
Payroll tax deferral	87	173
Other	396	500
Valuation allowance	(325)	(454)
Total deferred income tax assets	7,497	7,774
Deferred income tax liabilities:
Retirement benefits	(105)	(29)
Investments	(334)	(421)
Lease and rents	(4,947)	(5,368)
Depreciation and amortization	(8,381)	(8,750)
Total deferred income tax liabilities	(13,767)	(14,568)
Net deferred income tax liabilities	$ (6,270)	$ (6,794)