CONDENSED CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Held to maturity, Fair Value	$ 78,194	$ 82,126
Allowance for loan losses	$ 21,405	$ 21,202
Preferred stock, par value
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value
Common stock, shares authorized	499,000,000	499,000,000
Common stock, shares issued	54,138,910	54,138,910
Common stock, shares outstanding	49,904,074	49,800,126
Treasury stock, shares	4,234,836	4,338,784