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Consolidated Statemens of Income and Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Income Statement [Abstract]
Changes in unrealized losses on marketable debt securities, tax	$ 0.0	$ (0.3)	$ (0.1)	$ (0.3)
Amortization of pension and postretirement plans actuarial loss and prior service cost, tax	$ (0.3)	$ (0.4)	$ (0.9)	$ (1.0)

X

- Definition

Tax effect of the adjustment out of other comprehensive income for prior service costs and net loss recognized as a component of net periodic benefit cost during the period.

+ References

No definition available.

+ Details

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X

- References

No definition available.

+ Details

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X

- Definition

Amount, before adjustment, of tax expense (benefit) for unrealized holding gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Excludes tax expense (benefit) for unrealized gain (loss) on investment in debt security measured at amortized cost (held-to-maturity) from transfer to available-for-sale.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 12
-SubTopic 10
-Topic 220
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482790/220-10-45-12

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 10A
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482790/220-10-45-10A

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