Share-Based Compensation (Details)	12 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Stock options [Member]
Fair value assumptions for share-based compensation awards
Average risk-free interest rate	1.85%	1.76%	1.61%
Expected dividend yield	2.21%	2.78%	2.25%
Expected volatility	24.00%	29.00%	31.00%
Expected term (years)	5 years 1 month	5 years 1 month	5 years 1 month
Performance shares [Member]
Fair value assumptions for share-based compensation awards
Average risk-free interest rate	1.35%	1.21%	0.96%
Expected dividend yield	2.20%	2.75%	2.22%
Expected volatility	23.00%	22.00%	24.00%

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- Definition

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.

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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.

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- Definition

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

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- Definition

Expected term of share-based compensation awards, 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 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.D.2)
-URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809

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