Shared-based Compensation - Additional Information (Detail) (USD $)	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to restricted stock awards	$ 1,300,000
Compensation cost recognition weighted average period	2 years 6 months
Share-based compensation arrangement by share-based payment award, options, grants in period, weighted average grant date fair value	$ 16.00
Sharebased compensation arrangement by sharebased payment award options expiration term	10 years
Sharebased compensation arrangement by sharebased payment award options vesting period	3 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, shares authorized under stock option plans, exercise price range, upper range limit	$ 31.55
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, shares authorized under stock option plans, exercise price range, lower range limit	$ 24.26
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock awards vested and charged	530,000	774,000
Total income tax benefit recognized related to restricted stock awards	210,000	243,000
Unrecognized compensation cost related to restricted stock awards	5,400,000
Compensation cost recognition weighted average period	2 years 8 months 12 days
Share based compensation expense	349,000	338,000
Award vesting period	5 years
Total Tax Benefit Recognized In Additional Paid-in Capital Upon Vesting Of Restricted Stock Awards	$ 165,000	$ 0

Expiration term for options outstanding during the reporting period.

No definition available.

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- Definition

Sharebased compensation arrangement by share-based payment award options vesting period during the reporting period.

+ References

No definition available.

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- Definition

Total tax benefit recognized in additional paid-in capital upon vesting of restricted stock awards.

+ References

No definition available.

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- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 1

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-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 14

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- Definition

The compensation expense recognized during the period pertaining to the deferred compensation arrangement.

+ References

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- Definition

Unrecognized cost of unvested share-based compensation awards.

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- Definition

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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-Publisher FASB

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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.

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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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