Postretirement Benefits - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Apr. 30, 2017	Jan. 31, 2017	Apr. 30, 2016	Apr. 30, 2017	Apr. 30, 2016
Compensation and Retirement Disclosure [Abstract]
Employer contributions	$ 24		$ 21	$ 46	$ 40
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year				65
Defined Benefit Plan, Cost of Providing Special or Contractual Termination Benefits Recognized During Period		$ 1
Defined Contribution Plan, Cost Recognized	$ 9		$ 8	$ 16	$ 15

No definition available.

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- Definition

Amount of contributions made by the employer to defined benefit plans.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(5)(ii)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 60
-Section 35
-Paragraph 123
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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- Definition

If applicable, the cost of providing special or contractual termination benefits recognized during the period on the projected benefit obligation.

+ References

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- Definition

Amount of employer's best estimate of contributions expected to be paid to the plan in the current remaining fiscal period.

+ References

No definition available.

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- Definition

The amount of the cost recognized during the period for defined contribution plans.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 70
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-URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942

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