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, 2016	$ 414,395	$ 1,820	$ 74,525	$ 421,826	$ (14,164)	$ (69,612)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	29,131	0	0	29,131	0	0
Other comprehensive income (loss)	(540)	0	0	0	(540)	0
Treasury Stock, Value, Acquired, Cost Method	(503)					(503)
Contribution of shares to ESOP	706	2	704	0	0	0
Employee Stock Ownership Plan (ESOP), Cash Contributions to ESOP	1,062	0	395	0	0	667
Cash Dividends	(30,682)	0	0	(30,682)	0	0
Balance at Dec. 31, 2017	413,569	1,822	75,624	420,275	(14,704)	(69,448)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	46,583	0	0	46,583	0	0
Other comprehensive income (loss)	(6,384)	0	0	0	(6,384)	0
Treasury Stock, Value, Acquired, Cost Method	(391)	0	0	0	0	(391)
Contribution of shares to ESOP	745	2	743	0	0	0
Employee Stock Ownership Plan (ESOP), Cash Contributions to ESOP	1,087	0	407	0	0	680
Cash Dividends	(12,508)	0	0	(12,508)	0	0
Balance at Dec. 31, 2018	442,701	1,824	76,774	456,716	(23,454)	(69,159)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	48,872	0	0	48,872	0	0
Other comprehensive income (loss)	15,953	0	0	0	15,953	0
Treasury Stock, Value, Acquired, Cost Method	(315)	0	0	0	0	(315)
Contribution of shares to ESOP	801	3	798	0	0	0
Employee Stock Ownership Plan (ESOP), Cash Contributions to ESOP	1,251	0	422	0	0	829
Cash Dividends	(13,533)	0	0	(13,533)	0	0
Balance at Dec. 31, 2019	$ 557,608	$ 2,005	$ 139,694	$ 492,055	$ (7,501)	$ (68,645)