Discontinued Operations Discontinued Operations - Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Cash provided by operating activities and used in investing activities for discontinued operations [Abstract]
Cash provided by operating activities	$ (778)	$ 382	$ 489
Cash used in investing activities	5,047	(77)	(88)
Network Power Systems Business | Discontinued Operations, Disposed of by Sale [Member]
Cash provided by operating activities and used in investing activities for discontinued operations [Abstract]
Cash provided by operating activities	(615)
Cash used in investing activities	3,952
Network Power Systems Business | Discontinued Operations, Held-for-sale [Member]
Cash provided by operating activities and used in investing activities for discontinued operations [Abstract]
Cash provided by operating activities		343	378
Cash used in investing activities		(33)	(48)
Power Generation, Motors and Drives Business | Discontinued Operations, Disposed of by Sale [Member]
Cash provided by operating activities and used in investing activities for discontinued operations [Abstract]
Cash provided by operating activities	(163)
Cash used in investing activities	$ 1,095
Power Generation, Motors and Drives Business | Discontinued Operations, Held-for-sale [Member]
Cash provided by operating activities and used in investing activities for discontinued operations [Abstract]
Cash provided by operating activities		39	111
Cash used in investing activities		$ (44)	$ (40)