Employee Benefit Plans - Schedule of Amounts Recognized in Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Sep. 30, 2021
Pension Plan
Recognized in accumulated other comprehensive income (loss) as of end of period (net of taxes)
Net actuarial loss	$ 27.8	$ (18.9)	$ (29.0)
Prior service (cost) benefit	(9.6)	(11.2)	(11.6)
Total	18.2	(30.1)	(40.6)
Postretirement Health and Other
Recognized in accumulated other comprehensive income (loss) as of end of period (net of taxes)
Net actuarial loss	2.7	(6.7)	(5.1)
Prior service (cost) benefit	10.2	11.3	11.5
Total	$ 12.9	$ 4.6	$ 6.4

Amount, after tax, of accumulated other comprehensive (income) loss for defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
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-URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920

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- Definition

Amount, after tax, of accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14A
-URI https://asc.fasb.org/extlink&oid=126968391&loc=SL7669686-108580

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
-Paragraph 1
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- Definition

Amount, after tax, of accumulated other comprehensive (income) loss for cost (credit) of benefit change attributable to participants' prior service from plan amendment or plan initiation of defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (j)
-URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-URI https://asc.fasb.org/extlink&oid=126968391&loc=SL7669686-108580

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