Income Taxes Income Tax (Details) - USD ($) $ in Millions		9 Months Ended	12 Months Ended
	Jan. 01, 2018	Jun. 30, 2018	Sep. 30, 2017
Income Tax [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		21.00%	35.00%
Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Amount		$ 300
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount		2,100
Unrecognized Tax Benefits, Period Increase (Decrease)		100
Unrecognized Tax Benefits		800	$ 900
Unrecognized tax benefits expected reduction due to resolutions of open tax matters		200
Unrecognized Tax Benefits that Would Impact Effective Tax Rate		$ 100
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
Income Tax [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		24.50%
Minimum | Scenario, Plan
Income Tax [Line Items]
Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Percent	13.00%
Maximum | Scenario, Plan
Income Tax [Line Items]
Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Percent	16.00%