Note 16. Income Taxes Irish Rate Rec (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Operating Loss Carryforwards [Line Items]
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount		$ 136	$ 336
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount		0	15
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount	$ (67)	(92)	(13)
Effective Income Tax Rate Reconciliation, Deduction, Amount	21
Effective Income Tax Rate Reconciliation, Tax Credit, Amount		7	6
Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Amount			75
Unrecognized Tax Benefits, Period Increase (Decrease)		471
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount		14	(13)
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount		7	(5)
Income Tax Expense (Benefit)	99	$ 1,839	$ 418
IRELAND
Operating Loss Carryforwards [Line Items]
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount	133
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount	(10)
Effective Income Tax Rate Reconciliation, Deduction, Amount	28
Effective Income Tax Rate Reconciliation, Tax Credit, Amount	13
Effective Income Tax Rate Reconciliation, Equity in Earnings (Losses) of Unconsolidated Subsidiary, Amount	(19)
Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Amount	30
Effective Income Tax Rate Reconciliation, Tax Credit, Foreign, Amount	11
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	10
Unrecognized Tax Benefits, Period Increase (Decrease)	50
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount	21
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount	3
Income Tax Expense (Benefit)	$ 99