Employee Benefit Plans (Options Outstanding and Exercisable) (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2020 USD ($) $ / shares shares
$ 45.01 - $ 50.00 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum	$ 45.01
Range of Exercise Prices, Maximum	50.00
50.01 - 55.00 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum	50.01
Range of Exercise Prices, Maximum	55.00
65.01 - 70.00 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum	65.01
Range of Exercise Prices, Maximum	70.00
70.01 - 75.00 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum	70.01
Range of Exercise Prices, Maximum	75.00
75.01 - 80.00 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum	75.01
Range of Exercise Prices, Maximum	$ 80.00
Options Outstanding [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Number of Shares, Options Outstanding \| shares	1,739,559
Weighted-Average Exercise Price, Options Outstanding	$ 66.11
Weighted- Average Remaining Contractual Life in Years	3 years 2 months 15 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value \| $	$ 36,745
Options Outstanding [Member] \| $ 45.01 - $ 50.00 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Number of Shares, Options Outstanding \| shares	204,480
Weighted-Average Exercise Price, Options Outstanding	$ 48.00
Weighted- Average Remaining Contractual Life in Years	9 months 25 days
Options Outstanding [Member] \| 50.01 - 55.00 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Number of Shares, Options Outstanding \| shares	282,204
Weighted-Average Exercise Price, Options Outstanding	$ 54.56
Weighted- Average Remaining Contractual Life in Years	1 year 9 months 21 days
Options Outstanding [Member] \| 65.01 - 70.00 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Number of Shares, Options Outstanding \| shares	509,221
Weighted-Average Exercise Price, Options Outstanding	$ 65.11
Weighted- Average Remaining Contractual Life in Years	4 years 8 months 1 day
Options Outstanding [Member] \| 70.01 - 75.00 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Number of Shares, Options Outstanding \| shares	275,654
Weighted-Average Exercise Price, Options Outstanding	$ 71.39
Weighted- Average Remaining Contractual Life in Years	2 years 9 months 18 days
Options Outstanding [Member] \| 75.01 - 80.00 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Number of Shares, Options Outstanding \| shares	468,000
Weighted-Average Exercise Price, Options Outstanding	$ 78.95
Weighted- Average Remaining Contractual Life in Years	3 years 8 months 26 days
Options Exercisable [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Number of Shares, Options Exercisable \| shares	1,739,559
Weighted-Average Exercise Price, Options Exercisable	$ 66.11
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value \| $	$ 36,745
Options Exercisable [Member] \| $ 45.01 - $ 50.00 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Number of Shares, Options Exercisable \| shares	204,480
Weighted-Average Exercise Price, Options Exercisable	$ 48.00
Options Exercisable [Member] \| 50.01 - 55.00 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Number of Shares, Options Exercisable \| shares	282,204
Weighted-Average Exercise Price, Options Exercisable	$ 54.56
Options Exercisable [Member] \| 65.01 - 70.00 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Number of Shares, Options Exercisable \| shares	509,221
Weighted-Average Exercise Price, Options Exercisable	$ 65.11
Options Exercisable [Member] \| 70.01 - 75.00 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Number of Shares, Options Exercisable \| shares	275,654
Weighted-Average Exercise Price, Options Exercisable	$ 71.39
Options Exercisable [Member] \| 75.01 - 80.00 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Number of Shares, Options Exercisable \| shares	468,000
Weighted-Average Exercise Price, Options Exercisable	$ 78.95

Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

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The number of shares reserved for issuance pertaining to the outstanding exercisable stock options as of the balance sheet date in the customized range of exercise prices for which the market and performance vesting condition has been satisfied.

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The number of shares reserved for issuance pertaining to the outstanding stock options as of the balance sheet date for all option plans in the customized range of exercise prices.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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The ceiling of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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Weighted average exercise price as of the balance sheet date for those equity-based payment arrangements exercisable and outstanding.

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The weighted average price as of the balance sheet date at which grantees could acquire the underlying shares with respect to all outstanding stock options which are in the customized range of exercise prices.

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Weighted average remaining contractual term of outstanding stock options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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