Consolidated Condensed Statements of Financial Condition (Parenthetical) - USD ($) $ in Thousands		Jun. 30, 2018	Dec. 31, 2017
Held-to-maturity, fair value (in dollars)	[1]	$ 607	$ 649
Loans receivable, allowance (in dollars)		$ 27,321	$ 26,683
Common stock, par value (in dollars per share)		$ 0.01	$ 0.01
Common stock, shares authorized		50,000,000	50,000,000
Common Stock, Shares, Issued		25,398,992	25,425,682
Common stock, shares outstanding		20,396,178	20,312,082
Accumulated other comprehensive income, tax effect (in dollars)		$ (860)	$ 117
Treasury stock, shares		5,002,814	5,113,600
Preferred Stock [Member]
Preferred stock, par value (in dollars per share)		$ 0	$ 0
Preferred stock, shares authorized		4,963,000	4,963,000
Preferred stock, shares issued		0	0
Cumulative Preferred Stock [Member]
Preferred stock, par value (in dollars per share)		$ 0.01	$ 0.01
Preferred stock, shares authorized		37,000	37,000
Preferred stock, shares issued		0	0

[1] FHLMC, FNMA, and GNMA certificates are residential mortgage-backed securities.