Stock Incentive Plans - Summary of Stock Option Activity (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding as of Beginning of year	57
Exercised	(22)
Forfeited/Cancelled	0
Outstanding as of Ending of year	35
Outstanding, Weighted Average Exercise Price per Share, Beginning Balance	$ 11.69
Exercised, Weighted Average Exercise Price per Share	$ 11.00
Forfeited/Cancelled, Weighted Average Exercise Price per Share	$ 0.00
Outstanding, Weighted Average Exercise Price per Share, Ending Balance	$ 12.14
Exercised, Total Intrinsic Value of Options Exercised	$ 269
Incentive Stock Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding as of Beginning of year	22
Exercised	(22)
Forfeited/Cancelled	0
Outstanding as of Ending of year	0
Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding as of Beginning of year	35
Exercised	0
Forfeited/Cancelled	0
Outstanding as of Ending of year	35

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (d)(2)

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- Definition

For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 10

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- Definition

Weighted average price of options that were either forfeited or expired.

+ References

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- Definition

Number of options outstanding, including both vested and non-vested options.

+ References

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- Definition

Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

+ References

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- Definition

Weighted average price at which option holders acquired shares when converting their stock options into shares.

+ References

No definition available.

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- Definition

Number of share options (or share units) exercised during the current period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

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