Employee Benefit Plans - Net Periodic Defined Benefit Pension Costs (Parenthetical) (Detail) - U.S. Defined Benefit Plans [Member] $ in Millions	3 Months Ended
	Dec. 31, 2020 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Settlement charge	$ 6
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Settlement Gain (Loss), Statement of Income or Comprehensive Income [Extensible List]	Other income (expense)