Income Taxes - Tax Charges and Benefits Recorded Directly to Stockholders' Equity (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Tax Effect of Other Comprehensive Income	$ 5.0	$ 156.5	$ 120.2

Amount of tax expense (benefit) allocated to other comprehensive income (loss).

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