Discontinued Operations Discontinued Operations - Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Cash provided by operating activities and used in investing activities for discontinued operations [Abstract]
Cash from operating activities	$ 0	$ (778)	$ 382
Cash from investing activities	$ 0	5,047	(77)
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 from operating activities		(615)
Cash from 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 from operating activities			343
Cash from investing activities			(33)
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 from operating activities		(163)
Cash from 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 from operating activities			39
Cash from investing activities			$ (44)