Stock-based Compensation - Schedule of Compensation Cost for Share-based Payment (Details) - USD ($)	12 Months Ended	24 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Before tax stock-based compensation expense	$ 8,159,000	$ 7,959,000	$ 6,105,000
Tax benefit	(2,917,000)	(2,832,000)	0	$ 0
After tax stock-based compensation expense	5,242,000	5,127,000	6,105,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Before tax stock-based compensation expense	274,000	534,000	697,000
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Before tax stock-based compensation expense	$ 7,885,000	$ 7,425,000	$ 5,408,000

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.

Reference 1: 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.F)
-URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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The amount of expense, net of income tax, 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.

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The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income 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 (h)(1)(i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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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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