Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

+ Details

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- Definition

Fixed interest rate related to the interest rate derivative.

+ References

No definition available.

+ Details

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- Definition

The estimated value of gains (losses), net anticipated to be transferred in the future from accumulated other comprehensive income into earnings.

+ References

No definition available.

+ 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

Number of interest rate derivative instruments held by the entity at the reporting date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5579245-113959

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- Details

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- Details

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Fair Value of Financial Instruments - Cash Flow Hedges of Interest Rate Risk (Details)	6 Months Ended
	Mar. 31, 2018 USD ($)	Sep. 30, 2017 USD ($)	Jul. 31, 2015 interest_rate_swap_agreement
Interest rate swap \| Cash flow hedging
Derivative [Line Items]
Derivative instrument, gain (loss) reclassification from AOCI to income	$ 300,000
Interest rate swap one \| Cash flow hedging
Derivative [Line Items]
Derivative, fixed interest rate (as a percent)	2.2625%
Designated as hedging instrument \| Interest rate swap
Derivative [Line Items]
Derivative, notional amount	$ 325,000,000	$ 375,000,000
Designated as hedging instrument \| Interest rate swap \| Cash flow hedging
Derivative [Line Items]
Number of interest rate derivatives held \| interest_rate_swap_agreement			1
Designated as hedging instrument \| Interest rate swap one \| Cash flow hedging
Derivative [Line Items]
Derivative, notional amount	$ 325,000,000