Derivative Instruments Changes in Fair Value Hedges on Income (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Oct. 31, 2015	Oct. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Net impact on Consolidated Statements of Earnings	$ 0	$ 0
Interest Rate Swap [Member] \| Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest rate swap gain (loss)	(3)	9
Debt [Member] \| Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Adjustments to carrying value of long-term debt	$ 3	$ (9)

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4A

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-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5618551-113959

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

-Publisher FASB

-Name Accounting Standards Codification

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Amount of increase in the fair value of derivatives recognized in the income statement.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4C

-Subparagraph (a),(c),(d),(e)

-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624171-113959

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4A

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-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5618551-113959

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Amount of decrease in the fair value of derivatives recognized in the income statement.

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