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Stock-Based Compensation - Additional Information (Detail) - USD ($) | 1 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Jan. 31, 2021 | Jul. 31, 2020 | Jan. 31, 2020 | Jul. 31, 2019 | Jan. 31, 2019 | Jul. 31, 2018 | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |
Total shareholder return performance measurement period |  |  |  |  |  |  | 3 years |  |  |
Restricted stock unit awards granted |  |  |  |  |  |  | 616,000 | 1,139,000 | 790,000 |
Weighted average grant date fair value of restricted stock units granted |  |  |  |  |  |  | $ 72,760 | $ 39,080.00 | $ 45,990 |
Stock price |  |  |  |  |  |  | $ 72.61 | $ 37.95 | $ 47.70 |
Tax benefit from compensation expense |  |  |  |  |  |  | $ 13,060,000 | $ 8,360,000 | $ 12,036,000 |
Total unrecognized expense related to non-vested restricted stock unit awards and stock options |  |  |  |  |  |  | $ 44,000,000 |  |  |
Unrecognized expense related to non-vested restricted stock unit awards and stock options expected to be recognized over weighted average period, in years |  |  |  |  |  |  | 2 years 4 months 24 days |  |  |
Maximum percent of shares allowed to purchase |  |  |  |  |  |  | 10.00% |  |  |
Fair market value |  |  |  |  |  |  | $ 25,000 |  |  |
Maximum number of shares allowed to purchase |  |  |  |  |  |  | 6,000 |  |  |
Percentage of common stock price paid |  |  |  |  |  |  | 85.00% |  |  |
Common stock issued to employees |  | 200,000 | 200,000 | 300,000 | 400,000 | 300,000 |  |  |  |
Value of common stock issued to employees per share |  | $ 71.83 |  | $ 40.72 |  | $ 32.36 | $ 101.91 | $ 57.96 | $ 26.67 |
Number of shares available for grant |  |  |  |  |  |  | 6,123,000 | 6,727,000 | 7,874,000 | 8,605,000
Stock Based Compensation Relating To Retirement Agreement |  |  |  |  |  |  | $ 44,906,000 | $ 37,897,000 | $ 33,577,000 |
Retirement Agreement [Member] |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |
Stock Based Compensation Relating To Retirement Agreement |  |  |  |  |  |  | 2,100,000 |  |  |
Stock Options |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |
Cash received from employees, employee stock options exercises |  |  |  |  |  |  | 3,800,000 | 3,700,000 | 1,000,000.0 |
Tax benefit from compensation expense |  |  |  |  |  |  | $ 1,500,000 | $ 2,000,000.0 | $ 400,000 |
Percentage of common stock price paid |  |  |  |  |  |  | 100.00% |  |  |
Stock Options | Minimum [Member] |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |
Period of stock granted to employees and executive officers vest in equal installments |  |  |  |  |  |  | 4 years |  |  |
Stock Options | Maximum [Member] |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |
Period of stock granted to employees and executive officers vest in equal installments |  |  |  |  |  |  | 7 years |  |  |
Restricted Stock Units |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |
Restricted stock unit awards granted |  |  |  |  |  |  | 616,000 | 1,139,000 | 790,000 |
Restricted Stock Units | Employees |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |
Period of stock granted to employees and executive officers vest in equal installments |  |  |  |  |  |  | 4 years |  |  |
Restricted Stock Units | Director |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |
Period of stock granted to employees and executive officers vest in equal installments |  |  |  |  |  |  | 1 year |  |  |
Percentage of awards vesting on the first anniversary of grant date |  |  |  |  |  |  | 100.00% |  |  |
TSR Performance-Based Restricted Stock Units |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |
Total shareholder return performance measurement period |  |  |  |  |  |  | 3 years |  |  |
Share-based compensation arrangement by share-based payment award, description |  |  |  |  |  |  | capped at four times the grant date value for grants prior to 2019 |  |  |
Minimum age of retirement to be eligible for PRSUs |  |  |  |  |  |  | 60 years |  |  |
Minimum years of service for retirement to be eligible for PRSUs |  |  |  |  |  |  | 10 years |  |  |
Restricted stock unit awards granted |  |  |  |  |  |  | 100,000 | 100,000 | 100,000 |
Weighted average grant date fair value of restricted stock units granted |  |  |  |  |  |  | $ 89.93 | $ 51.51 | $ 54.85 |
Stock price |  |  |  |  |  |  | 72.10 | 37.95 | 47.70 |
TSR Performance-Based Restricted Stock Units | Measurement Input, Expected Dividend Payment [Member] |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |
Estimated annual dividend amount per share |  |  |  |  |  |  | $ 0.40 | $ 0.36 | $ 0.36 |
TSR Performance-Based Restricted Stock Units | Share-based Compensation Award, Tranche One |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |
Percentage of vesting of target shares upon performance achieved |  |  |  |  |  |  | 200.00% |  |  |
TSR Performance-Based Restricted Stock Units | Share-based Compensation Award, Tranche Two |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |
Percentage of vesting of target shares upon performance achieved |  |  |  |  |  |  | 0.00% |  |  |
Employee Stock Purchase Plan |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |
Number of shares available for grant |  |  |  |  |  |  | 1,400,000 |  |  |
PBIT Performance-Based Restricted Stock Units |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |
Restricted stock unit awards granted |  |  |  |  |  |  | 100,000 | 100,000 | 100,000 |
Weighted average grant date fair value of restricted stock units granted |  |  |  |  |  |  | $ 70.94 | $ 36.88 | $ 46.62 |
Service-Based Restricted Stock Units | Employees |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |
Restricted stock unit awards granted |  |  |  |  |  |  | 400,000 | 800,000 | 600,000 |
Weighted average grant date fair value of restricted stock units granted |  |  |  |  |  |  | $ 71.31 | $ 37.65 | $ 45.92 |
Service-Based Restricted Stock Units | Non Employee Directors And Certain Employees |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |
Restricted stock unit awards granted |  |  |  |  |  |  | 100,000 | 100,000 | 100,000 |
Weighted average grant date fair value of restricted stock units granted |  |  |  |  |  |  | $ 66.56 | $ 48.03 | $ 35.81 |
Service-Based Restricted Stock Units | Executive Officer |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |
Restricted stock unit awards granted |  |  |  |  |  |  | 100,000 | 100,000 | 100,000 |
Weighted average grant date fair value of restricted stock units granted |  |  |  |  |  |  | $ 20.93 | $ 10.64 | $ 12.17 |
Subsequent Event |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |
Common stock issued to employees | 100,000 |  |  |  |  |  |  |  |  |

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