Other Assets and Liabilites - Schedule of Right of Use Assets and Future Maturities of Lease Liabilities (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Right of Use Assets
Right-of-Use Asset, Operating Leases	$ 1,724		$ 1,724		$ 1,823
Right-of-Use Asset, Finance Leases	41		41		113
Operating Lease Liabilities, Payments Due
Total lease liabilities, Operating Leases	$ 2,061		$ 2,061		$ 2,121
Weighted Average Remaining Lease Term, Operating Leases	7 years 4 months 24 days		7 years 4 months 24 days		7 years 8 months 12 days
Weighted Average Discount Rate, Percent, Operating Leases	2.50%		2.50%		2.60%
Finance Lease Liabilities, Payments, Due
Total lease liabilities, Finance Leases	$ 48		$ 48		$ 123
Weighted Average Remaining Lease Term, Finance Leases	6 years 8 months 12 days		6 years 8 months 12 days		11 years 4 months 24 days
Weighted Average Discount Rate, Percent, Finance Leases	4.80%		4.80%		3.40%
Operating Lease, Cost	$ 97	$ 49	$ 193	$ 98