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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