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, 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
Balance at Dec. 31, 2020		586,946	23,887	331,951	(30,271)	2,797	915,310
Cumulative effect of change in accounting principle (see note 1b. "Authoritative Accounting Guidance Presentation"), net of tax				(2,925)			(2,925)
Balance on January 1 at Dec. 31, 2020		586,946	23,887	329,026	(30,271)	2,797	912,385
Net income				65,218			65,218
Other comprehensive income (loss), net of tax						(2,987)	(2,987)
Cash dividends declared on common stock				(7,964)			(7,964)
Exercise of stock options			45				45
Restricted stock grants
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			(1,283)				(1,283)
Repurchase of treasury stock					(2,411)		(2,411)
Stock-based compensation			1,957				1,957
Balance at Jun. 30, 2021		586,946	24,606	386,280	(32,682)	(190)	964,960
Balance at Mar. 31, 2021		586,946	23,621	358,441	(32,682)	(689)	935,637
Net income				32,219			32,219
Other comprehensive income (loss), net of tax						499	499
Cash dividends declared on common stock				(4,380)			(4,380)
Restricted stock grants
Stock-based compensation			985				985
Balance at Jun. 30, 2021		$ 586,946	$ 24,606	$ 386,280	$ (32,682)	$ (190)	$ 964,960