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Summary of Significant Accounting Policies - Fair Value of Marketable Securities (Detail) - USD ($) $ in Millions | Dec. 31, 2024 | Dec. 31, 2023
--- | --- | ---
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
Trading Securities | $ 6.3 | $ 6.0
Deferred Compensation Plan [Member] |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
Trading Securities | 2.2 | 1.3
Fair Value, Inputs, Level 1 |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
Trading Securities | 6.3 | 6.0
Fair Value, Inputs, Level 1 | Deferred Compensation Plan [Member] |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
Trading Securities | 2.2 | 1.3
Fair Value, Inputs, Level 1 | Equity Funds | Deferred Compensation Plan [Member] |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
Trading Securities | 2.0 | 1.1
Fair Value, Inputs, Level 1 | Money Market Funds |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
Trading Securities | 2.5 | 2.0
Fair Value, Inputs, Level 1 | Money Market Funds | Deferred Compensation Plan [Member] |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
Trading Securities | 0.1 | 0.1
Fair Value, Inputs, Level 1 | Fixed Income Funds |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
Trading Securities | 3.8 | 4.0
Fair Value, Inputs, Level 1 | Fixed Income Funds | Deferred Compensation Plan [Member] |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
Trading Securities | $ 0.1 | $ 0.1

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