Leases - Summary of Maturities of Lease Liabilities (Details) $ in Millions	Mar. 31, 2021 USD ($)
Amount of Operating Leases
Remainder of 2021	$ 434
2022	484
2023	420
2024	354
2025	293
Thereafter	854
Total undiscounted lease payment	2,839
Less: imputed interest	517	[1]
Present value of lease liabilities	2,322
Amount of Finance Leases
Remainder of 2021	3
2022	4
2023	4
2024	4
2025	4
Thereafter	22
Total undiscounted lease payment	41
Less: imputed interest	11	[1]
Present value of lease liabilities	30
Amount of Operating And Finance Leases, Total
Remainder of 2021	437
2022	488
2023	424
2024	358
2025	297
Thereafter	876
Total undiscounted lease payment	2,880
Less: imputed interest	528	[1]
Present value of lease liabilities	$ 2,352

[1] As the rate implicit in the lease cannot be readily determined, we use our incremental borrowing rate based on the information available at the lease commencement date in determining the imputed interest and present value of lease payments. We used the incremental borrowing rate on January 1, 2019 for operating leases that commenced prior to that date.