Stock-Based Compensation and Earnings Per Share - Awards of Equity Instruments (Details) - $ / shares	3 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Stock-Based Compensation
Maximum number of common stock shares that can be issued in respect of performance shares granted (in shares)	338,000
Options
Stock-Based Compensation
Number Issued (in shares)	0	646,600
Weighted Average Fair Value (in dollars per share)	$ 0.00	$ 17.18
Performance Shares
Stock-Based Compensation
Number Issued (in shares)	140,800	125,000
Weighted Average Fair Value (in dollars per share)	$ 138.68	$ 87.95
Restricted Stock Units
Stock-Based Compensation
Number Issued (in shares)	252,400	2,800
Weighted Average Fair Value (in dollars per share)	$ 133.36	$ 85.37

The maximum number of performance shares that could be issued based on the achievement of performance targets.

No definition available.

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- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ 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 (c)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

+ Details

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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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- Definition

Net number of share options (or share units) granted during the period.

+ 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 (c)(1)(iv)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

+ 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 (d)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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