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				45,648			45,648
Other comprehensive income (loss), net of tax						2,448	2,448
Cash dividends declared on common stock				(7,537)			(7,537)
Exercise of stock options			163				163
Restricted stock grants
Stock grants
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			1,999				1,999
Balance at Sep. 30, 2020		586,946	22,867	309,893	(30,271)	1,301	890,736
Balance at Jun. 30, 2020		586,946	22,069	288,688	(30,271)	309	867,741
Net income				24,786			24,786
Other comprehensive income (loss), net of tax						992	992
Cash dividends declared on common stock				(3,581)			(3,581)
Restricted stock grants
Stock-based compensation			798				798
Balance at Sep. 30, 2020		586,946	22,867	309,893	(30,271)	1,301	890,736
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				97,315			97,315
Other comprehensive income (loss), net of tax						(3,770)	(3,770)
Cash dividends declared on common stock				(12,345)			(12,345)
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					(8,043)		(8,043)
Proceeds from preferred stock issuance, net of costs	110,927						110,927
Stock-based compensation			3,202				3,202
Balance at Sep. 30, 2021	110,927	586,946	25,851	413,996	(38,314)	(973)	1,098,433
Balance at Jun. 30, 2021		586,946	24,606	386,280	(32,682)	(190)	964,960
Net income				32,097			32,097
Other comprehensive income (loss), net of tax						(783)	(783)
Cash dividends declared on common stock				(4,381)			(4,381)
Restricted stock grants
Stock grants
Repurchase of treasury stock					(5,632)		(5,632)
Proceeds from preferred stock issuance, net of costs	110,927						110,927
Stock-based compensation			1,245				1,245
Balance at Sep. 30, 2021	$ 110,927	$ 586,946	$ 25,851	$ 413,996	$ (38,314)	$ (973)	$ 1,098,433