Restructuring - Additional Information (Detail) $ in Millions	3 Months Ended
Dec. 31, 2018 USD ($)
Restructuring Cost And Reserve [Line Items]
Pre-tax restructuring charge	$ 60
After-tax restructuring charge	47
Employee Severance [Member]
Restructuring Cost And Reserve [Line Items]
Pre-tax restructuring charge	53
Accelerated Amortization of Equity Compensation Awards [Member]
Restructuring Cost And Reserve [Line Items]
Pre-tax restructuring charge	$ 7

Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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Data Type:	xbrli:monetaryItemType
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Period Type:	duration