CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (unaudited) - USD ($) $ in Thousands	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Total
Balance at Dec. 31, 2017		$ 412,726	$ 13,602	$ 160,025	$ (16,717)	$ (4,019)	$ 565,437
Reclassification of stranded tax effects (ASU 2018-02)				709		(709)
Cumulative effect of adopting ASU 2016-01				(55)		55
Net income				4,251			4,251
Other comprehensive Income (loss) net of tax						(2,834)	(2,834)
Cash dividends declared on common stock per share				(2,420)			(2,420)
Exercise of stock options			202				202
Restricted stock grants
Net performance units issued			(819)				(819)
Stock-based compensation			449				449
Balance at Mar. 31, 2018		412,546	13,434	162,510	(16,717)	(7,507)	564,266
Balance at Dec. 31, 2018		412,546	15,542	211,345	(16,717)	(8,789)	613,927
Net income				11,635			11,635
Other comprehensive Income (loss) net of tax						3,509	3,509
Cash dividends declared on common stock per share				(3,422)			(3,422)
Exercise of stock options			143				143
Restricted stock grants
Restricted stock units (4,904 shares)
Repurchase of treasury stock (13,000 shares)					(250)		(250)
Stock issued (3,032,496 shares) in acquisition of Greater Hudson Bank		56,025					56,025
Net performance units issued			196				196
Stock-based compensation			632				632
Balance at Mar. 31, 2019		$ 468,571	$ 16,513	$ 219,558	$ (16,967)	$ (5,280)	$ 682,395