Derivative Instruments (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2015	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Maximum length of time hedged in cash flow hedge	20 years
Credit Protection Purchased Notional Amounts	$ 7	$ 12
Credit Derivative Protection Purchased Fair Value Asset (Liability) (less than)	$ 1	$ (1)

Maximum potential amount of future undiscounted payments that could be required under the credit derivative, before reduction for potential recoveries under recourse or collateralization provisions.

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- Definition

Fair value of credit risk derivative asset after deduction of credit risk derivative liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4K

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5708775-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 15

-URI http://asc.fasb.org/extlink&oid=49121117&loc=d3e13495-108611

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=49121117&loc=d3e13433-108611

+ Details

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- References

No definition available.

+ Details

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- Definition

Maximum length of time over which the entity is hedging its exposure to the variability in future cash flows for forecasted transactions, excluding those forecasted transactions related to the payment of variable interest on existing financial instruments, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 30

-Section 50

-Paragraph 1

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=35736893&loc=d3e80748-113994

+ Details

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