Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Leased Assets [Line Items]
Operating Lease, Right-of-Use Asset	$ 458	$ 336	$ 0
Operating Lease, Weighted Average Remaining Lease Term	10 years 6 months	5 years 9 months 18 days
Operating Lease, Weighted Average Discount Rate, Percent	2.40%	3.70%
Operating Lease, Cost	$ 92	$ 80
Rent Expense, Net			$ 92
Operating Lease, Payments	91	77
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	202	137
Lessee, Operating Lease, Liability, Payments, Due Next Rolling Twelve Months	86
Lessee, Operating Lease, Liability, Payments, Due in Rolling Year Two	75
Lessee, Operating Lease, Liability, Payments, Due in Rolling Year Three	60
Lessee, Operating Lease, Liability, Payments, Due in Rolling Year Four	49
Lessee, Operating Lease, Liability, Payments, Due in Rolling Year Five	43
Lessee, Operating Lease, Liability, Payments, Due after Rolling Year Five	218
Lessee, Operating Lease, Liability, to be Paid	530
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(59)
Lessee, Leases Not Yet Commenced, Amount	$ 25
Lessee, Operating Lease, Lease Not yet Commenced, Term of Contract	15 years
Other Noncurrent Liabilities [Member]
Operating Leased Assets [Line Items]
Operating Lease, Liability, Noncurrent	$ 401	276
Operating Lease, Liability	471
Other Current Liabilities [Member]
Operating Leased Assets [Line Items]
Operating Lease, Liability, Current	$ 70	$ 67
Minimum [Member]
Operating Leased Assets [Line Items]
Lessee, Operating Lease, Term of Contract	1 year
Maximum [Member]
Operating Leased Assets [Line Items]
Lessee, Operating Lease, Term of Contract	56 years
Lessee, Operating and Finance Leases, Option to Extend	10 years