Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Operating Lease, Expense	$ 497	$ 323
Operating cash flows used in the measurement of operating lease liabilities	420	411
Operating lease right-of-use assets obtained in exchange for operating lease obligations	299	123
2021	632
2022	468
2023	335
2024	231
2025	158
Thereafter	646
Total undiscounted lease payments (1)	2,470
Less imputed interest	(472)
Operating Lease, Liability	1,998	1,338
Lessee, Operating Lease, Lease Not Yet Commenced, Amount	58
Operating lease liabilities, non-current	$ 1,516	$ 1,093
Operating Lease, Weighted Average Remaining Lease Term	8 years	8 years 7 months 6 days
Operating Lease, Weighted Average Discount Rate, Percent	3.10%	3.50%
Accrued Liabilities [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Liability, Current	$ 482	$ 245