Income Taxes - Expiration Dates of NOLs, Capital Loss and Other Tax Credit Carryforwards Before Valuation Allowances (Detail) $ in Millions	Sep. 30, 2023 USD ($)
Significant Tax Attributes And Dates Of Expiration [Line Items]
NOLs/Capital Losses	$ 2,112
Credits	136
2024 - 2030 [Member]
Significant Tax Attributes And Dates Of Expiration [Line Items]
NOLs/Capital Losses	1,051
Credits	31
2031 and Thereafter [Member]
Significant Tax Attributes And Dates Of Expiration [Line Items]
NOLs/Capital Losses	268
Credits	103
Indefinite Carryforwards [Member]
Significant Tax Attributes And Dates Of Expiration [Line Items]
NOLs/Capital Losses	793
Credits	$ 2