INVESTMENT SECURITIES, Amortized Cost, Unrealized Gains and Losses and Estimated Fair Values of Investments in Debt and Other Securities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Investment securities available-for-sale [Abstract]
Amortized cost	$ 636,903		$ 636,903		$ 683,784
Unrealized gains	4		4		102
Unrealized losses	(69,498)		(69,498)		(65,794)
Estimated fair value	567,409		567,409		618,092
Proceeds from sales of available-for-sale securities	0	$ 0	16,987	$ 6,349
Gross realized gains from sales of available-for-sale securities	0	0	96	0
Gross realized losses from sales of available-for-sale securities	0	$ 0	160	$ 152
U.S. Treasury Securities [Member]
Investment securities available-for-sale [Abstract]
Amortized cost	101,564		101,564		119,644
Unrealized gains	1		1		13
Unrealized losses	(4,587)		(4,587)		(5,842)
Estimated fair value	96,978		96,978		113,815
Securities of U.S. Government Agencies and Corporations [Member]
Investment securities available-for-sale [Abstract]
Amortized cost	123,822		123,822		128,697
Unrealized gains	0		0		20
Unrealized losses	(8,858)		(8,858)		(9,806)
Estimated fair value	114,964		114,964		118,911
Obligations of States and Political Subdivisions [Member]
Investment securities available-for-sale [Abstract]
Amortized cost	51,386		51,386		58,955
Unrealized gains	1		1		13
Unrealized losses	(6,903)		(6,903)		(5,642)
Estimated fair value	44,484		44,484		53,326
Collateralized Mortgage Obligations [Member]
Investment securities available-for-sale [Abstract]
Amortized cost	112,079		112,079		114,983
Unrealized gains	1		1		0
Unrealized losses	(20,780)		(20,780)		(19,633)
Estimated fair value	91,300		91,300		95,350
Mortgage-backed Securities [Member]
Investment securities available-for-sale [Abstract]
Amortized cost	248,052		248,052		261,505
Unrealized gains	1		1		56
Unrealized losses	(28,370)		(28,370)		(24,871)
Estimated fair value	$ 219,683		$ 219,683		$ 236,690