Short-Term and Long-Term Debt (Schedule Of Debt) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Current maturities of long-term debt		$ 300
Total short-term debt		300
Total long-term debt	$ 6,682	6,067
Fixed rate, swap	5.00%
Debt repurchase option, Repayment as percent of principal	100.00%
Long-term Debt [Member]
Debt Instrument [Line Items]
Senior Long Term Notes	$ 4,868	4,364
Term loans	250	250
Capital securities	1,213	1,213
Unamortized premiums (discounts)	(6)	(4)
Unamortized debt issuance costs	(38)	(34)
Unamortized adjustments from discontinued hedges	370	118
Fair value hedge on interest rate swap agreements	25	160
Total long-term debt	$ 6,682	6,067
4.85% notes, due 2021 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Senior Long Term Notes		296
Interest rate	4.85%
4.20% notes, due 2022 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Senior Long Term Notes	$ 300	300
Interest rate	4.20%
4.00% notes, due 2023 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Senior Long Term Notes	$ 500	500
Interest rate	4.00%
3.35% notes, due 2025 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Senior Long Term Notes	$ 300	300
Interest rate	3.35%
3.625% notes, due 2026 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Senior Long Term Notes	$ 400	400
Interest rate	3.625%
3.80% notes, due 2028 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Senior Long Term Notes	$ 500	500
Interest rate	3.80%
3.05% notes, due 2030 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Senior Long Term Notes	$ 500	500
Interest rate	3.05%
3.40% notes, due 2031 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Senior Long Term Notes	$ 500
Interest rate	3.40%
6.15% notes, due 2036 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Senior Long Term Notes	$ 243	243
Interest rate	6.15%
6.30% notes, due 2037 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Senior Long Term Notes	$ 375	375
Interest rate	6.30%
7.00% notes, due 2040 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Senior Long Term Notes	$ 500	500
Interest rate	7.00%
4.35% notes, due 2048 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Senior Long Term Notes	$ 450	450
Interest rate	4.35%
4.375% notes, due 2050 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Senior Long Term Notes	$ 300
Interest rate	4.375%
LIBOR + 87.5 bps loan, due 2024 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Term loans	$ 250	250
Variable rate	0.875%
LIBOR +236 bps, due 2066 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Capital securities	$ 722	722
Variable rate	2.36%
LIBOR +204 bps, due 2067 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Capital securities	$ 491	$ 491
Variable rate	2.04%

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Debt repurchase option, Repayment as percent of principal

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The fair value hedge associated with forward based contracts on certain long-term debt agreements in which two parties agree to swap periodic payments that are fixed at the outset of the swap contract with variable payments based on a market interest rate (index rate) over a specified period.

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Amount of short-term debt and current maturity of long-term debt and capital lease obligations due within one year or the normal operating cycle, if longer.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Amount, after accumulated amortization, of debt discount (premium).

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Fixed interest rate related to the interest rate derivative.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Including the current and noncurrent portions, carrying value at the balance sheet date of a financial instrument used to receive debt funding on a regular basis with original maturities ranging from 5-10 years.

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Carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion. Senior note holders are paid off in full before any payments are made to junior note holders.

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