Income Taxes Income Tax (Details) - USD ($) $ in Millions		6 Months Ended	12 Months Ended
	Jan. 01, 2018	Mar. 31, 2018	Sep. 30, 2017
Income Tax [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent			35.00%
Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Amount		$ 350
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount		2,000
Unrecognized Tax Benefits, Period Increase (Decrease)		100
Unrecognized Tax Benefits		900
Unrecognized tax benefits expected reduction due to resolutions of open tax matters		296
Unrecognized Tax Benefits that Would Impact Effective Tax Rate		$ 131
Cash and Cash Equivalents [Member]
Income Tax [Line Items]
Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Percent		15.50%
Residual Earnings [Member]
Income Tax [Line Items]
Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Percent		8.00%
Scenario, Plan [Member]
Income Tax [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		24.50%
Minimum | Scenario, Plan [Member]
Income Tax [Line Items]
Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Percent	13.00%
Maximum | Scenario, Plan [Member]
Income Tax [Line Items]
Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Percent	16.00%