CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Capital	Retained earnings	Accumulated Other Comprehensive Income/(Loss)	Treasury Stock
Balance at Dec. 31, 2013	$ 386,195	$ 1,811	$ 71,074	$ 357,083	$ (13,969)	$ (29,804)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	33,772	0	0	33,772	0	0
Other comprehensive income (loss)	(560)	0	0	0	(560)	0
Treasury Stock, Value, Acquired, Cost Method	(14,633)					(14,633)
Contribution of shares to ESOP	1,072	4	1,068	0	0
Employee Stock Ownership Plan (ESOP), Cash Contributions to ESOP	1,253	0	263	0	0	990
Cash Dividends	(12,885)	0	0	(12,885)	0	0
Balance at Dec. 31, 2014	394,214	1,815	72,405	377,970	(14,529)	(43,447)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	30,196	0	0	30,196	0	0
Other comprehensive income (loss)	5,128	0	0	0	5,128	0
Treasury Stock, Value, Acquired, Cost Method	(8,698)	0	0	0	0	(8,698)
Contribution of shares to ESOP	715	2	713	0	0	0
Employee Stock Ownership Plan (ESOP), Cash Contributions to ESOP	1,294	0	278	0	0	1,016
Cash Dividends	(12,533)	0	0	(12,533)	0	0
Balance at Dec. 31, 2015	410,316	1,817	73,396	395,633	(9,401)	(51,129)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	38,413	0	0	38,413	0	0
Other comprehensive income (loss)	(4,763)	0	0	0	(4,763)	0
Treasury Stock, Value, Acquired, Cost Method	(19,396)	0	0	0	0	(19,396)
Contribution of shares to ESOP	684	3	681	0	0	0
Employee Stock Ownership Plan (ESOP), Cash Contributions to ESOP	1,361	0	448	0	0	913
Cash Dividends	(12,220)	0	0	(12,220)	0	0
Balance at Dec. 31, 2016	$ 414,395	$ 1,820	$ 74,525	$ 421,826	$ (14,164)	$ (69,612)