Property, Plant and Equipment Schedule of Property, Plant and Equipment (Details) - USD ($) $ in Millions	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Property, Plant and Equipment [Abstract]
Buildings and improvements	$ 2,537	$ 2,445
Subscriber systems	573	571
Machinery and equipment	6,049	5,572
Construction in progress	1,324	1,252
Land	363	373
Total property, plant and equipment	10,846	10,213
Less accumulated depreciation	(4,675)	(4,092)
Property, plant and equipment - net	$ 6,171	$ 6,121	$ 5,632