Discontinued Operations - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Discontinued Operations Disclosures
Earnings (Loss), net of tax	$ (125)	$ 45	$ 193
Diluted earnings from discontinued operations per common share	$ (0.19)	$ 0.07	$ 0.28
Discontinued Operations, Disposed of by Sale [Member]
Discontinued Operations Disclosures
Payments for income taxes and repatriation costs, discontinued operations cash flow	$ 700
Discontinued Operations, Held-for-sale [Member]
Discontinued Operations Disclosures
Cash payments for separation costs		$ 179
Combined, Network Power and Power Generation, motors and Drives Business [Member] | Discontinued Operations, Disposed of by Sale [Member]
Discontinued Operations Disclosures
Benefit from ceasing depreciation and amortization on assets for discontinued businesses held-for-sale	32
Income tax expense for repatriation of sales proceeds and cash from discontinued operations	109
Combined, Network Power and Power Generation, motors and Drives Business [Member] | Discontinued Operations, Held-for-sale [Member]
Discontinued Operations Disclosures
Separation Costs, Fees		77	$ 10
Earnings (Loss) from discontinued operations		344	245
Separation Costs, Income Tax Expense		143	42
Benefit from ceasing depreciation and amortization on assets for discontinued businesses held-for-sale		24
After-tax separation costs related to strategic portfolio repositioning actions		299	52
Network Power Systems Business | Discontinued Operations, Disposed of by Sale [Member]
Discontinued Operations Disclosures
Agreed-upon purchase price of business	4,000
Earnings (Loss), net of tax	(6)
After tax gain on completion of sale of business	125
Disposal gain (loss), pretax	519
Network Power Systems Business | Discontinued Operations, Held-for-sale [Member]
Discontinued Operations Disclosures
Earnings (Loss), net of tax		179	117
Power Generation, Motors and Drives Business | Discontinued Operations, Disposed of by Sale [Member]
Discontinued Operations Disclosures
Agreed-upon purchase price of business	1,200
Earnings (Loss), net of tax	(119)
After tax loss on completion of sale of business	173
Disposal gain (loss), pretax	$ 36
Power Generation, Motors and Drives Business | Discontinued Operations, Held-for-sale [Member]
Discontinued Operations Disclosures
Earnings (Loss), net of tax		(134)	$ 76
Loss on write down of assets		$ 103