v3.20.4
Leases - Schedule of Components of Lease Expense (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Operating leases:    
Operating lease expense $ 451 $ 426
Finance leases:    
Amortization of leased assets 348 299
Interest on lease liabilities 100 104
Total finance lease expense 448 403
Total lease expense $ 899 $ 829