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Deferred Compensation (Detail) - USD ($) shares in Millions, $ in Millions		3 Months Ended				6 Months Ended		12 Months Ended
	Mar. 01, 2025	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Investments And Employee Deferred Compensation Plan [Line Items]
Vesting period, years	3 years
Deferred Equity Participation Plan (DEPP)
Investments And Employee Deferred Compensation Plan [Line Items]
Vesting period, years						1 year
Awards approved by committee, value			$ 22.2		$ 23.2
Charge to compensation expenses related to awards		$ 5.2		$ 5.6		$ 8.7	$ 9.6
Unearned deferred compensation, value						$ 87.2		$ 77.0
Unearned deferred compensation, shares (in shares)						2.1		2.2
Total intrinsic value of unvested equity based awards						$ 659.4		$ 616.4
Cash and equity awards with aggregate fair value vested and distributed to participants						16.9	17.9
Deferred Equity Participation Plan Sub Plans
Investments And Employee Deferred Compensation Plan [Line Items]
Awards approved by committee, value			2.3		2.3
Charge to compensation expenses related to awards		0.4		0.6		0.9	1.1
Distributions from the sub-plans						$ 3.8	2.3
Deferred Equity Participation Plan Sub Plans | Maximum
Investments And Employee Deferred Compensation Plan [Line Items]
Vesting period, years						15 years
Deferred Equity Participation Plan Sub Plans | Minimum
Investments And Employee Deferred Compensation Plan [Line Items]
Vesting period, years						5 years
Deferred Cash Participation Plan (DCPP)
Investments And Employee Deferred Compensation Plan [Line Items]
Vesting period, years						5 years
Awards approved by committee, value			$ 7.8		$ 8.1
Charge to compensation expenses related to awards		$ 2.3		$ 5.1		$ 7.0	9.9
Cash and equity awards with aggregate fair value vested and distributed to participants						$ 23.0	$ 13.6

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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.F)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479830/718-10-S99-1

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-Topic 718
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-Section 50
-Paragraph 2
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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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