Income Taxes - Expiration of Tax Credit Carryforwards (Detail) $ in Millions	Dec. 31, 2021 USD ($)
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	$ 363
2020 Tax Loss Carryforwards
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	363
2021 Tax Loss Carryforwards
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	10
2022 Tax Loss Carryforwards
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	11
2023 Tax Loss Carryforwards
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	11
2024 Tax Loss Carryforwards
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	19
2025 Tax Loss Carryforwards
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	22
2026-2030 Tax Loss Carryforwards
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	49
Later Tax Loss Carryforwards
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	188
Unlimited Tax Loss Carryforwards
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	$ 53