Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Sep. 30, 2018
Class of Stock [Line Items]
Equity Securities Registered, Value			$ 500.0
Common Stock Available for Issuance, Value Remaining	$ 394.3
Stock-based compensation expense	0.3	$ 0.5
At-the-market Equity Offering Program, Common Stock Available for Issuance	$ 100.0
At-the-market Equity Offering Program, Common Stock Issued	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	24,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 17.08

At-the-market Equity Offering Program, Common Stock Available for Issuance

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At-the-market Equity Offering Program, Common Stock Issued

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Common Stock Available for Issuance, Value Remaining

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- Definition

The dollar amount of equity securities registered under the entity's registration statement.

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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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Amount of noncash expense for share-based payment arrangement.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
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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).

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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=120381028&loc=d3e5070-113901

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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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