INVESTMENTS (Summary of Amortized Costs and Estimated Fair Values of Available-For-Sale Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Abstract]
Amortized Cost, Total	$ 777,621	$ 796,960
Available-for-sale securities, at fair value (amortized cost of $777,621 and $796,960, respectively)	686,423	695,875
Obligations of states and political subdivisions
Debt Securities, Available-for-sale [Abstract]
Amortized Cost, Total	49,142	49,678
Unrealized Gains	41	11
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	132	463
Available-for-sale securities, at fair value (amortized cost of $777,621 and $796,960, respectively)	49,051	49,226
MBS issued or guaranteed by U.S. government-sponsored enterprises
Debt Securities, Available-for-sale [Abstract]
Amortized Cost, Total	585,249	598,845
Unrealized Gains	214	131
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	77,632	84,957
Available-for-sale securities, at fair value (amortized cost of $777,621 and $796,960, respectively)	507,831	514,019
CMO issued or guaranteed by U.S. government-sponsored enterprises
Debt Securities, Available-for-sale [Abstract]
Amortized Cost, Total	117,552	122,760
Unrealized Gains	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	11,319	13,413
Available-for-sale securities, at fair value (amortized cost of $777,621 and $796,960, respectively)	106,233	109,347
Subordinated corporate bonds
Debt Securities, Available-for-sale [Abstract]
Amortized Cost, Total	25,678	25,677
Unrealized Gains	0	3
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	2,370	2,397
Available-for-sale securities, at fair value (amortized cost of $777,621 and $796,960, respectively)	23,308	23,283
Total AFS debt securities
Debt Securities, Available-for-sale [Abstract]
Amortized Cost, Total	777,621	796,960
Unrealized Gains	255	145
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	91,453	101,230
Available-for-sale securities, at fair value (amortized cost of $777,621 and $796,960, respectively)	$ 686,423	$ 695,875

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
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-Publisher FASB
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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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-Name Accounting Standards Codification
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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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