Income Taxes Temporary Differences And Carryforwards in Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2021	Sep. 30, 2020
Deferred tax assets
Accrued expenses and reserves	$ 407	$ 474
Employee and retiree benefits	148	286
Property, plant and equipment	369	182
Net operating loss and other credit carryforwards	6,293	6,306
Research and development	42	112
Operating lease liabilities	334	304
Other, net	28	99
Gross deferred tax assets	7,621	7,763
Valuation allowances	(5,853)	(5,518)
Net deferred tax assets	1,768	2,245
Deferred tax liabilities
Joint ventures and partnerships	346	730
Intangible assets	776	734
Operating lease right-of-use asset	334	304
Deferred Tax Liabilities, Gross	1,456	1,768
Deferred Tax Assets (Liabilities), Net	312	$ 477
Operating Loss Carryforwards	23,700
Net Operating Loss Carry Forwards That Will Expire	13,200
Tax Credit Carryforward, Amount	$ 35