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Deferred Compensation (Detail) - USD ($) shares in Millions, $ in Millions |  | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | --- | ---
Mar. 01, 2025 | Sep. 30, 2025 | Mar. 31, 2025 | Sep. 30, 2024 | Mar. 31, 2024 | Sep. 30, 2025 | Sep. 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 |  | $ 4.6 |  | $ 5.7 |  | $ 13.3 | $ 15.3 |
Unearned deferred compensation, value |  |  |  |  |  | $ 83.8 |  | $ 77.0
Unearned deferred compensation, shares (in shares) |  |  |  |  |  | 1.9 |  | 2.2
Total intrinsic value of unvested equity based awards |  |  |  |  |  | $ 596.3 |  | $ 616.4
Cash and equity awards with aggregate fair value vested and distributed to participants |  |  |  |  |  | 54.6 | 20.1 |
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 |  | 0.5 |  | 1.3 | 1.6 |
Distributions from the sub-plans |  |  |  |  |  | $ 8.9 | 3.0 |
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 |  | $ 3.6 |  | $ 4.6 |  | $ 10.6 | 14.5 |
Cash and equity awards with aggregate fair value vested and distributed to participants |  |  |  |  |  | $ 27.0 | $ 37.2 |

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