Leases Lessee (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
Lessee, Lease, Description [Line Items]
Lease charges	$ 42	$ 62	$ 98	$ 119
Operating lease right-of-use assets	2,714		2,714		$ 2,596
Operating Lease, Liability, Current	513		513		479
Long-term operating lease liabilities	2,226		2,226		2,140
Operating Leases, Rent Expense, Minimum Rentals	30		30
Property leases [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Cost	128	179	313	356
Variable Lease, Cost	20	74	56	126
Lease, Cost	148	$ 253	369	482
Operating lease right-of-use assets	2,714		2,714		2,596
Long-term operating lease liabilities	2,225		2,225		2,140
Operating Lease, Liability	$ 2,738		$ 2,738		$ 2,619
Operating Lease, Weighted Average Remaining Lease Term	8 years 9 months 18 days		8 years 9 months 18 days		8 years 10 months 24 days
Operating Lease, Weighted Average Discount Rate, Percent	4.12%		4.12%		4.31%
Operating Lease, Payments			$ 327	378
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability			$ (455)	$ (17)