Stock-Based Compensation Plans - Summary of Stock Option Activity Under All Plans (Parenthetical) (Detail) $ in Thousands	9 Months Ended
Sep. 30, 2015 USD ($)
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Aggregate intrinsic value of stock options outstanding	$ 1,260
Aggregate intrinsic value of stock options exercisable	923
Aggregate intrinsic values of stock options expected to vest	$ 1,243
Weighted average remaining contractual lives of stock options outstanding, years	7 years
Weighted average remaining contractual lives of stock options exercisable, years	5 years 8 months 12 days
Weighted average remaining contractual lives of stock options expected to vest, years	7 years

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

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

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Amount by which the current fair value of the underlying stock exceeds the exercise price of fully vested and expected to vest options outstanding.

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

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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 remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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

+ References

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

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

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

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