v3.20.4
Income Taxes - Expiration of Tax Loss Carryforwards (Detail)
$ in Millions
Dec. 31, 2020
USD ($)
Operating Loss Carryforwards [Line Items]  
Tax loss carryforwards $ 737
Disallowed interest carryforward (276)
2020 Tax Loss Carryforwards  
Operating Loss Carryforwards [Line Items]  
Tax loss carryforwards 737
2021 Tax Loss Carryforwards  
Operating Loss Carryforwards [Line Items]  
Tax loss carryforwards 0
2022 Tax Loss Carryforwards  
Operating Loss Carryforwards [Line Items]  
Tax loss carryforwards 12
2023 Tax Loss Carryforwards  
Operating Loss Carryforwards [Line Items]  
Tax loss carryforwards 2
2024 Tax Loss Carryforwards  
Operating Loss Carryforwards [Line Items]  
Tax loss carryforwards 3
2025 Tax Loss Carryforwards  
Operating Loss Carryforwards [Line Items]  
Tax loss carryforwards 81
2026-2030 Tax Loss Carryforwards  
Operating Loss Carryforwards [Line Items]  
Tax loss carryforwards 160
Later Tax Loss Carryforwards  
Operating Loss Carryforwards [Line Items]  
Tax loss carryforwards 70
Unlimited Tax Loss Carryforwards  
Operating Loss Carryforwards [Line Items]  
Tax loss carryforwards $ 409