Financial Instruments - Outstanding Instruments (Detail)
$ in Millions, £ in Billions
12 Months Ended
Dec. 31, 2021
USD ($)
Dec. 31, 2020
USD ($)
Nov. 30, 2021
USD ($)
Nov. 30, 2021
GBP (£)
Disclosure of detailed information about hedges [Line Items]        
Currency received Canadian dollar fixed Canadian dollar fixed    
Currency paid U.S. dollar fixed U.S. dollar fixed    
Hedged Risk Foreign exchange Foreign exchange    
Year of Maturity 2025 2025    
Principal Amount $ 999 $ 999 $ 3,500 £ 2.6