Debt (Schedule Of Outstanding Debt) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Current portion of long-term debt	$ 517	$ 1,215
Short-term debt	517	1,215
Long-term debt	11,313	11,956
Long-term debt, net	10,796	10,741
Senior notes – 2.35% due 2020
Debt Instrument [Line Items]
Long-term debt	$ 0	500
Interest rate	2.35%
Senior notes – 3.50% due 2020
Debt Instrument [Line Items]
Long-term debt	$ 0	698
Interest rate	3.50%
Senior notes – 4.80% due 2021
Debt Instrument [Line Items]
Long-term debt	$ 500	499
Interest rate	4.80%
Senior notes – Floating rate due 2021
Debt Instrument [Line Items]
Long-term debt	$ 0	298
Senior notes – 2.75% due 2022
Debt Instrument [Line Items]
Long-term debt	$ 499	498
Interest rate	2.75%
Senior notes – 3.30% due 2023
Debt Instrument [Line Items]
Long-term debt	$ 349	349
Interest rate	3.30%
Senior notes – 4.05% due 2023
Debt Instrument [Line Items]
Long-term debt	$ 249	249
Interest rate	4.05%
Senior notes – 3.50% due 2024
Debt Instrument [Line Items]
Long-term debt	$ 598	597
Interest rate	3.50%
Senior notes – 3.875% due 2024
Debt Instrument [Line Items]
Long-term debt	$ 995	994
Interest rate	3.875%
Senior notes – 3.50% due 2025
Debt Instrument [Line Items]
Long-term debt	$ 498	497
Interest rate	3.50%
Senior notes – 1.349% due 2026
Debt Instrument [Line Items]
Long-term debt	$ 677	609
Interest rate	1.349%
Senior notes – 3.75% due 2026
Debt Instrument [Line Items]
Long-term debt	$ 597	597
Interest rate	3.75%
Senior notes – 4.375% due 2029
Debt Instrument [Line Items]
Long-term debt	$ 1,499	1,499
Interest rate	4.375%
Senior notes – 1.979% due 2030
Debt Instrument [Line Items]
Long-term debt	$ 664	607
Interest rate	1.979%
Senior notes – 2.25% due 2030
Debt Instrument [Line Items]
Long-term debt	$ 737	0
Interest rate	2.25%
Senior notes – 5.875% due 2033
Debt Instrument [Line Items]
Long-term debt	$ 298	298
Interest rate	5.875%
Senior notes – 4.75% due 2039
Debt Instrument [Line Items]
Long-term debt	$ 495	494
Interest rate	4.75%
Senior notes – 4.35% due 2047
Debt Instrument [Line Items]
Long-term debt	$ 493	492
Interest rate	4.35%
Senior notes – 4.20% due 2048
Debt Instrument [Line Items]
Long-term debt	$ 592	592
Interest rate	4.20%
Senior notes – 4.90% due 2049
Debt Instrument [Line Items]
Long-term debt	$ 1,237	1,237
Interest rate	4.90%
Mortgage – 5.70% due 2035
Debt Instrument [Line Items]
Long-term debt	$ 331	345
Interest rate	5.70%
Other
Debt Instrument [Line Items]
Long-term debt	$ 5	$ 7