Stockholders' Equity - Determining Fair Value (Details)	12 Months Ended
Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2016
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility (range)	25.00%
Weighted average expected volatility	25.00%	23.00%	22.00%
Risk-free interest rate (range)	2.84%
Expected dividend yield	0.72%
Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average expected volatility	23.00%	20.00%	25.00%
Minimum \| Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility (range)		22.00%	22.00%
Risk-free interest rate (range)		1.65%	0.98%
Expected dividend yield		0.97%	1.06%
Minimum \| Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility (range)	20.00%	18.00%	23.00%
Risk-free interest rate (range)	1.05%	0.30%	0.06%
Expected dividend yield	0.87%	1.09%	1.13%
Maximum \| Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility (range)		23.00%	26.00%
Risk-free interest rate (range)		1.70%	1.49%
Expected dividend yield		1.17%	1.36%
Maximum \| Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility (range)	25.00%	21.00%	26.00%
Risk-free interest rate (range)	1.96%	0.89%	0.47%
Expected dividend yield	1.10%	1.10%	1.34%

The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(iii)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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- Definition

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(ii)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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- Definition

The risk-free interest rate assumption that is used in valuing an option on its own shares.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(iv)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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- Definition

Weighted average expected volatility rate of share-based compensation awards.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(ii)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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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

No definition available.

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