Computations of Basic and Diluted Earnings Per Share (Parenthetical) (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share Disclosure [Line Items]
Weighted average shares of participating unvested restricted stock	762	888	684	801