Contingencies - Additional Information (Details) $ in Millions	3 Months Ended
	Dec. 31, 2018 USD ($) site claim	Dec. 31, 2017 USD ($)	Sep. 30, 2018 USD ($) claim	Sep. 30, 2009 USD ($)
Loss Contingencies [Line Items]
Environmental accrual balance	$ 16		$ 17
Discounted amount environmental accrual for on-going operations maintenance and monitoring	13
Undiscounted amount environmental accrual for on-going operations maintenance and monitoring	14
Asbestos related liability remeasurement income	31	$ 0
Maremont Asbestos
Loss Contingencies [Line Items]
Number of pending claims | claim			1,700
Damages sought	51
Asbestos related liability remeasurement income	$ 31
Obligation period for asbestos personal injury claims	41 years
Pending and future claims			$ 107
Estimated insurance recoveries			$ 24
Rockwell Asbestos
Loss Contingencies [Line Items]
Number of pending claims | claim	1,100		1,400
Pending and future claims	$ 101		$ 103
Estimated insurance recoveries			68
Low Range
Loss Contingencies [Line Items]
Site contingency, accrual, discount rate	2.25%
Low Range | Maremont Asbestos
Loss Contingencies [Line Items]
Possible loss			107
Low Range | Rockwell Asbestos
Loss Contingencies [Line Items]
Possible loss			103
High Range
Loss Contingencies [Line Items]
Site contingency, accrual, discount rate	3.00%
High Range | Maremont Asbestos
Loss Contingencies [Line Items]
Possible loss			195
High Range | Rockwell Asbestos
Loss Contingencies [Line Items]
Possible loss			186
Superfund Sites
Loss Contingencies [Line Items]
Number of Superfund environmental sites | site	10
Environmental costs reasonably possible	$ 23
Environmental accrual balance	11		12
Non-Superfund Sites
Loss Contingencies [Line Items]
Environmental costs reasonably possible	11
Environmental accrual balance	5		5
Indemnity Obligations
Loss Contingencies [Line Items]
Guarantee obligations recorded	$ 9		9	$ 28
Value Added Tax | Future tax years
Loss Contingencies [Line Items]
Increased liability			$ 3