Derivatives (Details 2-Fair Value Hedges) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Debentures Due 2017 [Member] \| Fair Value Hedging [Member] \| Designated as Hedging Instrument [Member] \| Interest Rate Contract [Member]
Derivative [Line Items]
Derivative, Notional Amount	$ 0	$ 600
Weighted-average, LIBOR-based, floating rate	0.00%	5.10%
Debentures Due 2018 [Member] \| Not Designated as Hedging Instrument [Member] \| Interest Rate Swap [Member]
Derivative [Line Items]
Aggregate Notional Amount - Interest Rate Swap Agreements	$ 0	$ 750
Derivative, Fixed Interest Rate	0.00%	1.57%
Debentures Due 2018 [Member] \| Fair Value Hedging [Member] \| Designated as Hedging Instrument [Member] \| Interest Rate Contract [Member]
Derivative [Line Items]
Derivative, Notional Amount	$ 0	$ 300
Weighted-average, LIBOR-based, floating rate	0.00%	5.04%

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

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- Definition

Aggregate Notional Amount - Interest Rate Swap Agreements

+ References

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- Definition

Average variable interest rate related to the group of interest rate derivatives.

+ References

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- Definition

Fixed interest rate related to the interest rate derivative.

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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