Income Taxes Income Taxes, Continuing Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Income Tax, Continuing Operations [Line Items]
Operating Loss Carryforwards	$ 16,600
Income from Continuing Operations before Income Taxes, Domestic	868	$ 943	$ 418
Net Operating Loss Carry Forwards That Will Expire	6,500
Tax Credit Carryforward, Amount	$ 468
Earliest Tax Year [Member]
Income Tax, Continuing Operations [Line Items]
Expiration period of net operating loss carryforwards	Dec. 31, 2018
Tax Credit Carryforward, Expiration Date	Dec. 31, 2020
Latest Tax Year [Member]
Income Tax, Continuing Operations [Line Items]
Expiration period of net operating loss carryforwards	Dec. 31, 2037
Tax Credit Carryforward, Expiration Date	Dec. 31, 2024