Income Taxes Additional Information (Details) $ in Millions	3 Months Ended
	Dec. 31, 2017 USD ($)
Income Tax Disclosure [Abstract]
Other Tax Expense (Benefit)	$ 270
Expected Deferred Tax Asset Liability Reversal Rate	21.00%
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability	$ 290
Other Tax Expense Benefit Transition Tax	561
Transition tax payable	220
Transition Tax Estimated To Be Payable	$ 781