Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Effective tax rate	22.00%	30.00%	21.00%	(11.00%)
Deferred tax assets, valuation allowance	$ 0.5		$ 0.5
Unrecognized tax benefits, decrease due to expiration of certain federal statutes of limitations and voluntary filings	$ 0.7		$ 0.7

Amount of decrease reasonably possible in the next twelve months for the unrecognized tax benefit.

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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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