Borrowing Activity (Details) $ in Millions	6 Months Ended
	Mar. 31, 2018 USD ($)
Borrowings [Roll Forward]
Borrowings beginning balance	$ 25,291
Borrowings	5,515
Payments	(6,026)
Other Activity	(96)
Borrowings ending balance	24,684
Commercial paper with original maturities less than three months
Borrowings [Roll Forward]
Borrowings beginning balance	1,151
Borrowings	0	[1]
Payments	(764)	[1]
Other Activity	(2)
Borrowings ending balance	385
Commercial paper with original maturities greater than three months
Borrowings [Roll Forward]
Borrowings beginning balance	1,621
Borrowings	4,467
Payments	(2,331)
Other Activity	9
Borrowings ending balance	3,766
U.S. and European medium-term notes
Borrowings [Roll Forward]
Borrowings beginning balance	19,721
Borrowings	0
Payments	(1,300)
Other Activity	12
Borrowings ending balance	18,433
BAMTech Notes Payable [Member]
Borrowings [Roll Forward]
Borrowings beginning balance	1,581
Borrowings	0
Payments	(1,581)
Other Activity	0
Borrowings ending balance	0
Asia International Theme Parks borrowings
Borrowings [Roll Forward]
Borrowings beginning balance	1,145
Borrowings	0
Payments	0
Other Activity	81	[2]
Borrowings ending balance	1,226
Foreign currency denominated debt and other
Borrowings [Roll Forward]
Borrowings beginning balance	72
Borrowings	1,048
Payments	(50)
Other Activity	(196)	[3]
Borrowings ending balance	$ 874

[1] Borrowings and payments are reported net.

[2] The other activity is primarily the U.S. dollar weakening against the Chinese Renminbi.

[3] The other activity is primarily market value adjustments for debt with qualifying hedges.