Earnings Per Common Share - Historical Net Income and Weighted Average Number of Shares of Common Stock Outstanding (Detail) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share [Abstract]
Weighted average number of shares of common stock outstanding	23,621	23,459	23,591	23,453
Shares assumed issued (less shares assumed purchased for treasury) for stock-based compensation	465	326	362	362
Outstanding shares for diluted earnings per share calculation	24,086	23,785	23,953	23,815