Earnings Per Share - Calculation of Percentage of Net Income Allocable to Common Shareholders (Detail) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share [Abstract]
Basic weighted-average common shares	19,105,806	18,941,077	18,646,128
Add: Other common shares eligible for common dividends:
Weighted average restricted shares and stock options (including tax benefit component)	97,844	178,109	282,376
Diluted weighted average common shares	19,203,650	19,119,186	18,928,504