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Stock-Based Compensation Plans (Details) - USD ($) $ / shares in Units, $ in Millions | 3 Months Ended | 9 Months Ended |  |
--- | --- | --- | --- | ---
Sep. 30, 2024 | Sep. 30, 2023 | Sep. 30, 2024 | Sep. 30, 2023 | Dec. 31, 2023 | Jan. 01, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Common stock available under stock option plan (in shares) | 7,091,876 |  | 7,091,876 |  |  |
Vesting period |  |  | 3 years |  |  |
Options, outstanding, number (in shares) | 114,943 |  | 114,943 |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price | $ 48.63 |  | $ 48.63 |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term |  |  | 2 years 7 months 6 days |  |  |
Options, grants in period, gross (in shares) |  |  | 0 |  |  |
Plan 2020 |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Number of shares authorized to issue under share based compensation plans (in shares) |  |  |  |  |  | 12,500,000
Restricted Stock |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Share-based compensation arrangement age requirement to vest over original vesting period |  |  | 55 years |  |  |
Time in service requirement to vest over original vesting period |  |  | 10 years |  |  |
Nonvested awards, compensation cost not yet recognized | $ 24.4 |  | $ 24.4 |  | $ 18.5 |
Nonvested awards, compensation cost not yet recognized, period for recognition |  |  | 1 year |  |  |
Equity instruments other than options, vested in period, fair value | 0.3 | $ 0.1 | $ 28.3 | $ 23.8 |  |
Allocated share-based compensation expense, net of tax | 7.2 | 6.2 | 24.6 | 22.1 |  |
Allocated share-based compensation expense | $ 5.6 | $ 4.8 | $ 19.0 | $ 17.1 |  |
Equity instruments other than options, nonvested, number (in shares) | 1,671,657 |  | 1,671,657 |  | 1,741,486 |
Performance Shares |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Nonvested awards, compensation cost not yet recognized, period for recognition |  |  | 36 months |  |  |
Equity instruments other than options, nonvested, number (in shares) | 520,000 |  | 520,000 |  |  |
Total shareholder return performance measure, as a percentage | 15.00% |  | 15.00% |  |  |
Estimated vesting of shares based on performance shares (in shares) | 520,000 |  | 520,000 |  |  |
Minimum | Performance Shares |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Options, vested and expected to vest, exercisable, number (in shares) | 0 |  | 0 |  |  |
Maximum | Performance Shares |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Options, vested and expected to vest, exercisable, number (in shares) | 1,196,000 |  | 1,196,000 |  |  |
Maximum | Performance Shares | Issue Date 2022 And 2021 |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Award vesting rights, percentage |  |  | 230.00% |  |  |

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