Shareholders' Equity - Summary of Information about Stock Options Outstanding (Detail) shares in Thousands	12 Months Ended
Dec. 31, 2018 $ / shares shares
Exercise Price $9.91 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price	$ 9.91
Number Outstanding \| shares	10
Remaining Contractual Life (Years), Outstanding	3 months 29 days
Weighted Average Price, Outstanding	$ 9.91
Number Exercisable \| shares	10
Remaining Contractual Life (Years), Exercisable	3 months 29 days
Weighted Average Price, Exercisable	$ 9.91
Exercise Price $14.99 - $18.01 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price, Lower Range Limit	14.99
Exercise Price, Upper Range Limit	$ 18.01
Number Outstanding \| shares	28
Remaining Contractual Life (Years), Outstanding	1 year 2 months 4 days
Weighted Average Price, Outstanding	$ 16.61
Number Exercisable \| shares	28
Remaining Contractual Life (Years), Exercisable	1 year 2 months 4 days
Weighted Average Price, Exercisable	$ 16.61
Exercise Price $27.61 - $29.55 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price, Lower Range Limit	27.61
Exercise Price, Upper Range Limit	$ 29.55
Number Outstanding \| shares	200
Remaining Contractual Life (Years), Outstanding	6 years 3 months 3 days
Weighted Average Price, Outstanding	$ 28.58
Number Exercisable \| shares	108
Remaining Contractual Life (Years), Exercisable	3 years 4 months 13 days
Weighted Average Price, Exercisable	$ 27.76
Exercise Price $30.01 - $30.50
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price, Lower Range Limit	30.01
Exercise Price, Upper Range Limit	$ 30.50
Number Outstanding \| shares	275
Remaining Contractual Life (Years), Outstanding	6 years 10 months 9 days
Weighted Average Price, Outstanding	$ 30.37
Number Exercisable \| shares	159
Remaining Contractual Life (Years), Exercisable	5 years 6 months 7 days
Weighted Average Price, Exercisable	$ 30.27
Exercise Price $9.91 - $30.50 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price, Lower Range Limit	9.91
Exercise Price, Upper Range Limit	$ 30.50
Number Outstanding \| shares	513
Remaining Contractual Life (Years), Outstanding	6 years 2 months 8 days
Weighted Average Price, Outstanding	$ 28.52
Number Exercisable \| shares	305
Remaining Contractual Life (Years), Exercisable	4 years 2 months 8 days
Weighted Average Price, Exercisable	$ 27.46

Share based compensation shares authorized under stock option plans exercise price.

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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

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- Definition

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.

+ References

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-Publisher FASB
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-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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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
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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
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-SubTopic 10
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- Definition

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.

+ References

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- Definition

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

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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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
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-Topic 718
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- Definition

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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