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Retirement Plans - Reconciliation of Beginning and Ending Balances for Level 3 Assets of Plan Measured at Fair Value (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	$ 228.9	$ 212.5
Fair value of plan assets at end of year	312.5	228.9
Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	108.6	99.6
Settlements	(10.6)	(1.4)
Unrealized gain	8.8	10.4
Fair value of plan assets at end of year	$ 106.8	$ 108.6

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- Definition

Defined benefit plans, unrealized gains losses

+ References

No definition available.

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- Definition

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.

+ References

No definition available.

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- Definition

Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 17
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480482/715-20-55-17

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

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- Definition

Amount of payment, which decreases plan assets of defined benefit plan, for irrevocable action relieving primary responsibility for benefit obligation and eliminating risk for obligation and assets used to effect settlement. Transaction constituting settlement includes, but is not limited to, making lump-sum cash payment to participant in exchange for their rights to receive specified benefits and purchasing nonparticipating annuity contract.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
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-Section 50
-Paragraph 1
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

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