Benefit Plans - (Details) - USD ($) $ in Millions	12 Months Ended
Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2015
Retirement Benefits [Abstract]
Maximum percent of salary and bonus eligible for executive deferred compensation plan	75.00%
Executive deferred compensation plan liabilities	$ 83	$ 69
Maximum percent of pre tax salary eligible for contribution to employee plan	50.00%
Additional employer contribution for next six percent of salary (in percent)	125.00%
Additional salary contributed by the employee (in percent)	6.00%
Matching contributions	$ 49	$ 46	$ 44

Additional Employer Contribution For Next Six Percent Of Salary In Percent

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- Definition

Additional salary contributed by the employee in percent.

+ References

No definition available.

+ Details

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- Definition

Matching contributions.

+ References

No definition available.

+ Details

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- Definition

Maximum Percent of Pre Tax Salary Eligible For Contribution to Employee Plan.

+ References

No definition available.

+ Details

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- Definition

Maximum percent of salary bonus and commission eligible for executive deferred compensation plan.

+ References

No definition available.

+ Details

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- References

No definition available.

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- Definition

Aggregate carrying value as of the balance sheet date of the liabilities for all deferred compensation arrangements payable within one year (or the operating cycle, if longer). Represents currently earned compensation under compensation arrangements that is not actually paid until a later date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 710
-SubTopic 10
-Section 30
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6409875&loc=d3e20028-108363

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 710
-SubTopic 10
-Section 25
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=6409733&loc=d3e19512-108361

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