Summary of Activity Under Stock Plans (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Share-Based Payment Arrangement [Abstract]
Intrinsic value of options exercised	$ 56.8	$ 41.2	$ 17.8
Cash received from stock option exercises	52.0	51.7	35.8
Tax benefit related to stock award exercises	8.0	5.4	2.6
Stock-based compensation	22.9	21.2	17.1
Tax benefit related to stock-based compensation	$ 2.1	$ 1.7	$ 1.7

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

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

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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Amount of tax benefit for recognition of expense of award under share-based payment arrangement.

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Amount of tax benefit from exercise of option under share-based payment arrangement.

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Amount of cash inflow from exercise of option under share-based payment arrangement.

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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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