Other Assets and Liabilites - Schedule of Right of Use Assets and Future Maturities of Lease Liabilities (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Right of Use Assets
Right-of-Use Asset, Operating Leases	$ 1,773
Right-of-Use Asset, Finance Leases	43
Operating Lease Liabilities, Payments Due
2020	334
2021	382
2022	337
2023	284
2024	237
2025	78
Thereafter	671
Total lease payments, Operating Leases	2,323
Less: imputed interest, Operating Leases	244
Total lease liabilities, Operating Leases	$ 2,079
Weighted Average Remaining Lease Term, Operating Leases	7 years 6 months
Weighted Average Discount Rate, Percent, Operating Leases	2.60%
Finance Lease Liabilities, Payments, Due
2020	$ 10
2021	11
2022	11
2023	7
2024	5
2025	1
Thereafter	12
Total lease payments, Finance Leases	57
Less: imputed interest, Finance Leases	6
Total lease liabilities, Finance Leases	$ 51
Weighted Average Remaining Lease Term, Finance Leases	7 years 4 months 24 days
Weighted Average Discount Rate, Percent, Finance Leases	4.10%
Operating Lease, Cost	$ 96	$ 49