Stock-Based Compensation - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based payment award, award vesting period	3 years
Share-based compensation expense	$ 1.6	$ 1.0
Tax benefit from compensation expense	$ 0.6	$ 0.4
Target performance level (as a percent)	100.00%
Share-based compensation, compensation cost not yet recognized	$ 9.0
Share-based compensation, compensation cost not yet recognized, recognition period	2 years 11 months 2 days
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre-established target levels (as a percent)	0.00%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target performance level (as a percent)	150.00%
Pre-established target levels (as a percent)	150.00%
Performance shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Approximate number of shares to be issued (in shares)	412,608
Restricted shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of vested stock awards	$ 1.4

Pre-Established Targets, Performance-based Awards

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Share-based Compensation, Target Performance

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Share-based Payment Award, Maximum Number of Shares to be Issued

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- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
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Unrecognized cost of unvested share-based compensation awards.

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- Definition

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

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-Name Accounting Standards Codification
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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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- Definition

Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

+ References

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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.

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