Earnings per Share - Reconciles Shares Outstanding for Basic and Diluted Earnings Per Share (Detail) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Earnings Per Share [Abstract]
Weighted average shares issued net of Treasury shares	17,649	18,468	17,740	18,560
Less: Unallocated ESOP shares	(450)	(484)	(455)	(489)
Unallocated incentive award shares and shares held by deferred compensation plan	(94)	(95)	(91)	(94)
Average basic shares outstanding	17,105	17,889	17,194	17,977
Add: Effect of dilutive securities:
Shares held by deferred compensation plan	39	41	39	41
Average diluted shares outstanding	17,144	17,930	17,233	18,018