Acquisitions Changes in Carry Amount of Goodwill (Details) $ in Millions	6 Months Ended
	Mar. 31, 2018 USD ($)
Goodwill [Line Items]
Beginning balance	$ 31,426
Acquisitions	0
Dispositions	0
Other, net	(76)
Ending balance	31,350
Media Networks [Member]
Goodwill [Line Items]
Beginning balance	16,325
Acquisitions	0
Dispositions	0
Other, net	3
Ending balance	16,328
Parks And Resorts [Member]
Goodwill [Line Items]
Beginning balance	291
Acquisitions	0
Dispositions	0
Other, net	0
Ending balance	291
Studio Entertainment [Member]
Goodwill [Line Items]
Beginning balance	6,817
Acquisitions	0
Dispositions	0
Other, net	2
Ending balance	6,819
Consumer Products and Interactive [Member]
Goodwill [Line Items]
Beginning balance	4,393
Acquisitions	0
Dispositions	0
Other, net	1
Ending balance	4,394
Unallocated [Member]
Goodwill [Line Items]
Beginning balance	3,600	[1]
Acquisitions	0	[1]
Dispositions	0	[1]
Other, net	(82)	[1]
Ending balance	$ 3,518	[1]

[1] Unallocated amount will be allocated to the segments once the BAMTech purchase price allocation is finalized. Other, net represents the impact on goodwill of updates to our initial estimated fair value of intangible assets related to BAMTech.