Summary of Information About Share Options Exercisable and Outstanding (Detail)	12 Months Ended
Dec. 31, 2020 $ / shares shares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share options exercisable, number of shares \| shares	1,189,058
Share options exercisable, weighted average exercise price	$ 22.21
Share options outstanding, number of shares \| shares	1,529,026
Share options outstanding, weighted average exercise price	$ 19.90
$9.13
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of per share exercise price	$ 9.13
Share options exercisable, number of shares \| shares	50,067
Share options exercisable, weighted average exercise price	$ 9.13
Share options outstanding, number of shares \| shares	226,874
Share options outstanding, weighted average exercise price	$ 9.13
$9.46
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of per share exercise price	$ 9.46
Share options exercisable, number of shares \| shares	2,500
Share options exercisable, weighted average exercise price	$ 9.46
Share options outstanding, number of shares \| shares	5,000
Share options outstanding, weighted average exercise price	$ 9.46
$9.70
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of per share exercise price	$ 9.70
Share options exercisable, number of shares \| shares	210,359
Share options exercisable, weighted average exercise price	$ 9.70
Share options outstanding, number of shares \| shares	210,359
Share options outstanding, weighted average exercise price	$ 9.70
$9.75
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of per share exercise price	$ 9.75
Share options exercisable, number of shares \| shares	2,813
Share options exercisable, weighted average exercise price	$ 9.75
Share options outstanding, number of shares \| shares	3,750
Share options outstanding, weighted average exercise price	$ 9.75
$11.15
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of per share exercise price	$ 11.15
Share options exercisable, number of shares \| shares	92,946
Share options exercisable, weighted average exercise price	$ 11.15
Share options outstanding, number of shares \| shares	202,560
Share options outstanding, weighted average exercise price	$ 11.15
$12.23 - $14.17
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share options exercisable, number of shares \| shares	158,254
Share options exercisable, weighted average exercise price	$ 14.05
Share options outstanding, number of shares \| shares	158,254
Share options outstanding, weighted average exercise price	$ 14.05
$12.23 - $14.17 \| Minimum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of per share exercise price	12.23
$12.23 - $14.17 \| Maximum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of per share exercise price	14.17
$22.95
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of per share exercise price	$ 22.95
Share options exercisable, number of shares \| shares	150,391
Share options exercisable, weighted average exercise price	$ 22.95
Share options outstanding, number of shares \| shares	200,501
Share options outstanding, weighted average exercise price	$ 22.95
$28.05 - $28.54
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share options exercisable, number of shares \| shares	215,514
Share options exercisable, weighted average exercise price	$ 28.27
Share options outstanding, number of shares \| shares	215,514
Share options outstanding, weighted average exercise price	$ 28.27
$28.05 - $28.54 \| Minimum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of per share exercise price	28.05
$28.05 - $28.54 \| Maximum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of per share exercise price	28.54
$34.14
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of per share exercise price	$ 34.14
Share options exercisable, number of shares \| shares	162,639
Share options exercisable, weighted average exercise price	$ 34.14
Share options outstanding, number of shares \| shares	162,639
Share options outstanding, weighted average exercise price	$ 34.14
$38.36
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of per share exercise price	$ 38.36
Share options exercisable, number of shares \| shares	143,575
Share options exercisable, weighted average exercise price	$ 38.36
Share options outstanding, number of shares \| shares	143,575
Share options outstanding, weighted average exercise price	$ 38.36

Range of per share exercise price of share options.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

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.

+ References

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

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- Definition

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.

+ References

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

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- Definition

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

+ References

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

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- Definition

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.

+ References

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

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