Earnings Per Share - Weighted-Average Number of Shares of Common Stock Used to Calculate Basic and Diluted Earnings Per Share (Detail) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Abstract]
Weighted-average number of shares of common stock for calculating basic earnings per share	25,334	25,953	25,853	25,885
Effect of potentially dilutive securities from equity-based compensation	74	199	101	292
Weighted-average number of shares of common stock for calculating diluted earnings per share	25,408	26,152	25,954	26,177