Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023	Sep. 30, 2023
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits	$ 4.0		$ 4.0		$ 5.0
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%	21.00%	21.00%
State income taxes, net of federal benefit	3.40%	3.40%	3.40%	3.40%
Tax credits	(2.10%)	(1.50%)	(2.10%)	(1.50%)
Other	1.60%	1.20%	1.50%	0.90%
Other Expense
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits, Income Tax Indemnification Asset, Expense	$ 0.0		$ 1.6
Income Tax Information [Line Items]
Unrecognized Tax Benefits, Income Tax Indemnification Asset, Expense	$ 0.0		$ 1.6

Income Tax Information [Line Items]

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Unrecognized Tax Benefits, Income Tax Indemnification Asset, Expense

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-12

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
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-Section S99
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-1

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Percentage of the difference, between reported income tax expense (benefit) and the expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations, that is attributable to tax exempt income, equity in earnings (loss) of an unconsolidated subsidiary, minority interest income (expense), tax holiday, disposition of a business, disposition of an asset, repatriation of foreign earnings, repatriation of foreign earnings jobs creation act of 2004, change in enacted tax rate, prior year income taxes, change in deferred tax asset valuation allowance, and other adjustments.

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to state and local income tax expense (benefit), net of federal tax expense (benefit).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
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-URI https://asc.fasb.org//1943274/2147482685/740-10-50-12

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Amount of unrecognized tax benefits.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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