Leases - Schedule of Maturities of Operating and Finance Lease Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating Leases, 2021	$ 366
Operating Leases, 2022	327
Operating Leases, 2023	279
Operating Leases, 2024	245
Operating Leases, 2025	204
Operating Leases, Thereafter	425
Operating Leases, Total minimum lease payments	1,846
Less: Interest	306
Total operating lease liabilities	1,540	$ 1,184
Operating lease liabilities, current portion	286	228
Operating lease liabilities	1,254	956
Finance Leases, 2021	462
Finance Leases, 2022	446
Finance Leases, 2023	412
Finance Leases, 2024	299
Finance Leases, 2025	9
Finance Leases, Thereafter	7
Total minimum lease payments, Finance Leases	1,635
Less: Interest	167
Total finance lease liabilities	1,468	1,618
Net Carrying Value Finance leases, Current	374	386
Net Carrying Value Finance leases, Long-Term	$ 1,094	$ 1,232