Reportable Segments - Revenues by Component (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Revenue from External Customer [Line Items]
Total revenues	$ (3,090)	$ (3,073)
Eliminations - Revenue [Member]
Revenue from External Customer [Line Items]
Total revenues	(29)	(31)
Media Networks
Revenue from External Customer [Line Items]
Total revenues	(2,498)	(2,560)
Media Networks | Advertising [Member]
Revenue from External Customer [Line Items]
Total revenues	(1,230)	(1,308)
Media Networks | Affiliate Revenue [Member]
Revenue from External Customer [Line Items]
Total revenues	(1,169)	(1,139)
Media Networks | Consumer products, recreation and live events [Member]
Revenue from External Customer [Line Items]
Total revenues	(99)	(113)
Filmed Entertainment
Revenue from External Customer [Line Items]
Total revenues	(621)	(544)
Filmed Entertainment | Theatrical [Member]
Revenue from External Customer [Line Items]
Total revenues	(149)	(100)
Filmed Entertainment | Home entertainment [Member]
Revenue from External Customer [Line Items]
Total revenues	(178)	(183)
Filmed Entertainment | Licensing [Member]
Revenue from External Customer [Line Items]
Total revenues	(220)	(213)
Filmed Entertainment | Ancillary
Revenue from External Customer [Line Items]
Total revenues	$ (74)	$ (48)