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, 2018		$ 412,546	$ 15,542	$ 211,345	$ (16,717)	$ (8,789)	$ 613,927
Net income				30,916			30,916
Other comprehensive income (loss), net of tax						5,908	5,908
Cash dividends declared on common stock				(6,612)			(6,612)
Exercise of stock options			265				265
Restricted stock grants
Net restricted stock units issued
Repurchase of treasury stock					(5,175)		(5,175)
Net performance units issued			196				196
Stock issued in acquisition of Greater Hudson Bank		56,025					56,025
Restricted stock issued in acquisition of BoeFly, LLC			2,500				2,500
Stock-based compensation			1,274				1,274
Balance at Jun. 30, 2019		468,571	19,777	235,649	(21,892)	(2,881)	699,224
Balance at Mar. 31, 2019		468,571	16,513	219,558	(16,967)	(5,280)	682,395
Net income				19,281			19,281
Other comprehensive income (loss), net of tax						2,399	2,399
Cash dividends declared on common stock				(3,190)			(3,190)
Exercise of stock options			122				122
Restricted stock grants
Repurchase of treasury stock					(4,925)		(4,925)
Restricted stock issued in acquisition of BoeFly, LLC			2,500				2,500
Stock-based compensation			642				642
Balance at Jun. 30, 2019		468,571	19,777	235,649	(21,892)	(2,881)	699,224
Balance at Dec. 31, 2019		468,571	21,344	271,782	(29,360)	(1,147)	731,190
Net income				20,862			20,862
Other comprehensive income (loss), net of tax						1,456	1,456
Cash dividends declared on common stock				(3,956)			(3,956)
Exercise of stock options			163				163
Restricted stock grants
Net shares issued in satisfaction of restricted stock units earned
Net shares issued in satisfaction of performance units earned
Share redemption for tax withholdings on performance units and restricted stock units earned			(639)				(639)
Repurchase of treasury stock					(911)		(911)
Stock issued in acquisition of Bancorp of New Jersey		118,375					118,375
Stock-based compensation			1,201				1,201
Balance at Jun. 30, 2020		586,946	22,069	288,688	(30,271)	309	867,741
Balance at Mar. 31, 2020		586,946	21,746	273,825	(30,271)	1,464	853,710
Net income				14,832			14,832
Other comprehensive income (loss), net of tax						(1,155)	(1,155)
Cash dividends adjustment				31			31
Restricted stock grants
Share redemption for tax withholdings on performance units and restricted stock units earned			(342)				(342)
Stock-based compensation			665				665
Balance at Jun. 30, 2020		$ 586,946	$ 22,069	$ 288,688	$ (30,271)	$ 309	$ 867,741