Stock-Based Compensation - Fair Value of Options (Parenthetical) (Detail)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock price volatility, risk free interest period	5 years	5 years

Risk free rate equal to five year treasury bond rate.

No definition available.

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