Consolidated Statements of Financial Condition (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Statement Of Financial Position [Abstract]
Securities available for sale; cost	$ 1,049,130		$ 1,065,447
Loans receivable, allowance for loan losses	$ 6,713		$ 6,709
Preferred stock, par value	$ 0.01		$ 0.01
Preferred stock, shares authorized	5,000,000		5,000,000
Preferred stock, shares issued	0		0
Common stock, par value	$ 0.01		$ 0.01
Common stock, shares authorized	30,000,000		30,000,000
Common stock, shares issued	19,214,226	[1]	19,211,028	[1]
Common stock, shares outstanding	17,669,375	[1]	17,599,928	[1]
Treasury stock, shares	1,544,851		1,611,100

[1] Shares issued and outstanding have been adjusted to reflect the six-for-five stock split declared April 16, 2013.