v3.10.0.1
Income Taxes - Expiration of Tax Loss Carryforwards (Detail)
$ in Millions
Dec. 31, 2018
USD ($)
Operating Loss Carryforwards [Line Items]  
Tax loss carryforwards $ 795
2019 Tax Loss Carryforwards [Member]  
Operating Loss Carryforwards [Line Items]  
Tax loss carryforwards 22
2020 Tax Loss Carryforwards [Member]  
Operating Loss Carryforwards [Line Items]  
Tax loss carryforwards 6
2021 Tax Loss Carryforwards [Member]  
Operating Loss Carryforwards [Line Items]  
Tax loss carryforwards 1
2022 Tax Loss Carryforwards [Member]  
Operating Loss Carryforwards [Line Items]  
Tax loss carryforwards 16
2023 Tax Loss Carryforwards [Member]  
Operating Loss Carryforwards [Line Items]  
Tax loss carryforwards 3
2024-2028 Tax Loss Credit Carryforwards [Member]  
Operating Loss Carryforwards [Line Items]  
Tax loss carryforwards 129
Later Tax Loss Carryforwards [Member]  
Operating Loss Carryforwards [Line Items]  
Tax loss carryforwards 181
Unlimited Tax Credit Loss Carryforwards [Member]  
Operating Loss Carryforwards [Line Items]  
Tax loss carryforwards $ 437