SECURITIES - Securities Available for Sale (Details) - USD ($)	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Amortized cost and estimated fair value of securities available for sale
Amortized Cost	$ 762,543,000		$ 795,409,000
Unrealized Gains	319,000		6,587,000
Unrealized Losses	69,867,000		9,970,000
Estimated Fair Value	692,995,000		792,026,000
Amortized Cost
Within one year	1,963,000
After one, but within five years	104,071,000
After five, but within ten years	20,183,000
After ten years	469,000
Total	126,686,000
Amortized Cost	762,543,000		795,409,000
Fair Value
Within one year	1,952,000
After one, but within five years	98,146,000
After five, but within ten years	19,673,000
After ten years	432,000
Total	120,203,000
Total	692,995,000		792,026,000
Proceeds from sales and calls of securities resulting in gains or losses
Proceeds	0	$ 0
U.S. Treasury notes and bonds
Amortized cost and estimated fair value of securities available for sale
Amortized Cost	60,988,000		61,084,000
Unrealized Gains	0		27,000
Unrealized Losses	4,684,000		680,000
Estimated Fair Value	56,304,000		60,431,000
Amortized Cost
Amortized Cost	60,988,000		61,084,000
Fair Value
Total	56,304,000		60,431,000
Mortgage-backed securities, residential
Amortized cost and estimated fair value of securities available for sale
Amortized Cost	545,524,000		582,060,000
Unrealized Gains	16,000		4,032,000
Unrealized Losses	62,264,000		8,731,000
Estimated Fair Value	483,276,000		577,361,000
Amortized Cost
Without single maturity date	545,524,000
Amortized Cost	545,524,000		582,060,000
Fair Value
Without single maturity date	483,276,000
Total	483,276,000		577,361,000
Obligations of states and political subdivisions
Amortized cost and estimated fair value of securities available for sale
Amortized Cost	39,948,000		40,299,000
Unrealized Gains	10,000		2,004,000
Unrealized Losses	992,000		0
Estimated Fair Value	38,966,000		42,303,000
Amortized Cost
Amortized Cost	39,948,000		40,299,000
Fair Value
Total	38,966,000		42,303,000
Corporate bonds and notes
Amortized cost and estimated fair value of securities available for sale
Amortized Cost	25,750,000		22,750,000
Unrealized Gains	0		180,000
Unrealized Losses	817,000		82,000
Estimated Fair Value	24,933,000		22,848,000
Amortized Cost
Amortized Cost	25,750,000		22,750,000
Fair Value
Total	24,933,000		22,848,000
SBA loan pools
Amortized cost and estimated fair value of securities available for sale
Amortized Cost	90,333,000		89,216,000
Unrealized Gains	293,000		344,000
Unrealized Losses	1,110,000		477,000
Estimated Fair Value	89,516,000		89,083,000
Amortized Cost
Without single maturity date	90,333,000
Amortized Cost	90,333,000		89,216,000
Fair Value
Without single maturity date	89,516,000
Total	$ 89,516,000		$ 89,083,000