Stock-based Compensation Plans - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
Jun. 30, 2021	Jun. 30, 2020
Stock-Based Compensation Activity [Line Items]
Unrecognized compensation costs, nonvested awards, amount	$ 9.0
Unrecognized compensation costs, nonvested awards, weighted average recognition period	2 years 3 months 18 days
Stock Option Awards [Member]
Stock-Based Compensation Activity [Line Items]
Units granted	244,000	291,000
Weighted average grant date fair value per unit	$ 14.08	$ 14.12
Restricted Stock Awards [Member]
Stock-Based Compensation Activity [Line Items]
Units granted	68,000	64,000
Weighted average grant date fair value	$ 38.06	$ 41.50
Restricted Stock Unit Awards [Member]
Stock-Based Compensation Activity [Line Items]
Units granted	12,000	18,000
Weighted average grant date fair value	$ 45.13	$ 40.36
Employee Stock Purchase Plan [Member]
Stock-Based Compensation Activity [Line Items]
Shares issued	8,000	7,000

Stock-based compensation activity.

No definition available.

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- Definition

Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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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

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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).

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- Definition

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

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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.

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- Definition

Number of shares issued under share-based payment arrangement.

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