Stock-Based Compensation Expense - Additional Information (Detail)	12 Months Ended
Dec. 31, 2020 USD ($) group $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of groups within the employee population \| group	2
Estimated forfeiture rate for unvested options for senior management	7.00%
Estimated forfeiture rate for unvested options for all non-senior management	12.00%
Increase in compensation expense due to revised estimated forfeiture rates	$ 1,787,000	$ 499,000	$ 1,283,000
Weighted-average grant-date fair values of stock options granted \| $ / shares	$ 19.62	$ 18.62	$ 20.84
Total intrinsic values of stock options exercised	$ 166,796,000	$ 90,762,000	$ 52,629,000
Total fair values of stock options vested	45,998,000	38,974,000	31,106,000
Total unrecognized compensation expense related to non-vested stock options	$ 51,825,000
Recognition period for unrecognized compensation expense	1 year 8 months 12 days
Stock-based compensation expense	$ 42,661,000	45,589,000	41,090,000
Income tax benefit recognized related to stock-based compensation expense	6,569,000	7,756,000	7,317,000
Compensation expense capitalized	0	$ 0	$ 0
Stock-based compensation expense and the related income tax benefit recognized, credits	$ 1,401,000
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant under stock option plans \| shares	16,260,393
Vesting period for stock option plans
Expiration period of stock option plan	10 years
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, weighted-average exercise price \| $ / shares		$ 48.61	$ 0
Vested (in shares) \| shares	0	0	0
Minimum [Member] \| Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period for stock option plans	4 years
Minimum [Member] \| Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period for stock option plans	3 years
Maximum [Member] \| Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period for stock option plans	5 years
Maximum [Member] \| Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period for stock option plans	3 years

Employee service share based compensation recognized period costs capitalized amount.

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Estimated forfeiture rate for unvested options for all non-senior management.

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Estimated forfeiture rate for unvested options for senior management.

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Expiration period of stock option plan.

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Increase (decrease) in compensation expense due to revised estimated forfeiture rates.

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Number of groups within employee population.

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Share based compensation arrangement by share based payment award options vested fair value.

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Shares based compensation arrangement by shares based payment award options exercised intrinsic value.

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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of cost to be recognized for option under share-based payment arrangement.

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Amount of noncash expense for share-based payment arrangement.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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