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

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- Definition

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

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Common Stock Available for Issuance, Value Remaining

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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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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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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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Equity impact of the value of new stock issued during the period. Includes shares issued in an initial public offering or a secondary public offering.

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Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020	Sep. 30, 2020	Sep. 30, 2018
Class of Stock [Line Items]
Equity Securities Registered, Value						$ 500.0
Common Stock Available for Issuance, Value Remaining	$ 370.6		$ 370.6
Stock-based compensation expense	0.9	$ 0.8	1.2	$ 1.3
At-the-market Equity Offering Program, Common Stock Available for Issuance	$ 76.3		$ 76.3		$ 100.0
At-the-market Equity Offering Program, Common Stock Issued	1,000,000.0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period			232,320
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value			$ 23.12
Stock Issued During Period, Value, New Issues	$ 23.3
Retirement Eligible [Member]
Class of Stock [Line Items]
Stock-based compensation expense			$ 0.7	$ 0.5
Common Stock [Member]
Class of Stock [Line Items]
At-the-market Equity Offering Program, Common Stock Issued	1,018,503
Stock Issued During Period, Value, New Issues	$ 1.0