Stock Option Activity (Detail) (USD $)	3 Months Ended	12 Months Ended
Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2013
Share Based Compensation [Line Items]
Stock Options Granted, Number of Shares	250,000
Stock Option [Member]
Share Based Compensation [Line Items]
Number of Options Outstanding, Beginning Balance		194,493
Stock Options Granted, Number of Shares		250,000
Stock Options Exercised, Number of Shares		(28,229)
Stock Options Canceled, Forfeited or Expired, Number of Shares		(138,728)
Number of Options Outstanding, Ending Balance	277,536	277,536	194,493
Stock Options Exerciseable, Number of Shares	27,536	27,536
Options Outstanding, Beginning Balance, Weighted Average Exercise Price		$ 22.62
Stock Options Granted, Weighted Average Exercise Price		$ 26.65
Stock Options Exercised, Weighted Average Exercise Price		$ 19.97
Stock Options Canceled, Forfeited or Expired, Weighted Average Exercise Price		$ 22.86
Options Outstanding, Ending Balance, Weighted Average Exercise Price	26.40	$ 26.40	$ 22.62
Options Outstanding, Weighted Average Contractual Life		8 years 11 months 26 days	9 months 29 days
Stock Options Exerciseable, Weighted Average Exercise Price	24.14	$ 24.14
Stock Options Exerciseable, Weighted Average Contractual Life		2 months 5 days
Risk Free Rate		2.07%
Expected Volatility		50.55%
Expected Term		6 years 3 months
Fair Value		$ 13.50

The calculated fair value of a stock-based compensation award

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Measure of dispersion, in percentage terms (for instance, the standard deviation or variance), for a given stock price.

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Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The risk-free interest rate assumption that is used in valuing an option on its own shares.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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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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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.

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

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Net number of share options (or share units) granted during the period.

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

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

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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.

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

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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No definition available.

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

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