Debt (Schedule Of Outstanding Debt) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Current portion of long-term debt	$ 1,216	$ 1,215
Short-term debt	1,216	1,215
Long-term debt	12,748	11,956
Long-term debt, net	11,532	10,741
2.35% Senior Debt Obligations Due 2020
Debt Instrument [Line Items]
Long-term debt	$ 0	500
Interest rate	2.35%
3.50% Senior Debt Obligations Due 2020
Debt Instrument [Line Items]
Long-term debt	$ 700	698
Interest rate	3.50%
4.80% Senior Debt Obligations Due 2021
Debt Instrument [Line Items]
Long-term debt	$ 500	499
Interest rate	4.80%
Floating Rate Senior Debt Obligations Due 2021
Debt Instrument [Line Items]
Long-term debt	$ 299	298
2.75% Senior Debt Obligations Due 2022
Debt Instrument [Line Items]
Long-term debt	$ 499	498
Interest rate	2.75%
3.30% Senior Debt Obligations Due 2023
Debt Instrument [Line Items]
Long-term debt	$ 349	349
Interest rate	3.30%
4.05% Senior Debt Obligations Due 2023
Debt Instrument [Line Items]
Long-term debt	$ 249	249
Interest rate	4.05%
3.50% Senior Debt Obligations Due 2024
Debt Instrument [Line Items]
Long-term debt	$ 598	597
Interest rate	3.50%
3.875% Senior Debt Obligations Due 2024
Debt Instrument [Line Items]
Long-term debt	$ 995	994
Interest rate	3.875%
3.50% Senior Debt Obligations Due 2025
Debt Instrument [Line Items]
Long-term debt	$ 497	497
Interest rate	3.50%
1.349% Senior Debt Obligations Due 2026
Debt Instrument [Line Items]
Long-term debt	$ 641	609
Interest rate	1.349%
3.75% Senior Debt Obligations Due 2026
Debt Instrument [Line Items]
Long-term debt	$ 597	597
Interest rate	3.75%
4.375% Senior Debt Obligations Due 2029
Debt Instrument [Line Items]
Long-term debt	$ 1,499	1,499
Interest rate	4.375%
1.979% Senior Debt Obligations Due 2030
Debt Instrument [Line Items]
Long-term debt	$ 635	607
Interest rate	1.979%
2.250% Senior Debt Obligations Due 2030
Debt Instrument [Line Items]
Long-term debt	$ 737	0
Interest rate	2.25%
5.875% Senior Debt Obligations Due 2033
Debt Instrument [Line Items]
Long-term debt	$ 298	298
Interest rate	5.875%
4.75% Senior Debt Obligations Due 2039
Debt Instrument [Line Items]
Long-term debt	$ 495	494
Interest rate	4.75%
4.35% Senior Debt Obligation Due 2047
Debt Instrument [Line Items]
Long-term debt	$ 493	492
Interest rate	4.35%
4.20% Senior Debt Obligations Due 2048
Debt Instrument [Line Items]
Long-term debt	$ 592	592
Interest rate	4.20%
4.90% Senior Debt Obligations Due 2049
Debt Instrument [Line Items]
Long-term debt	$ 1,237	1,237
Interest rate	4.90%
5.70% Mortgage Due 2035
Debt Instrument [Line Items]
Long-term debt	$ 334	345
Interest rate	5.70%
$500 Million Two-Year Term Loan Facility
Debt Instrument [Line Items]
Long-term debt	$ 500	0
Other
Debt Instrument [Line Items]
Long-term debt	$ 4	$ 7