ACCUMULATED OTHER COMPREHENSIVE INCOME - Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 602,006	$ 609,102	$ 568,887	$ 704,906
Net current period other comprehensive (loss) income	(10,275)	(64,847)	11,278	(174,627)
Ending balance	591,995	562,063	591,995	562,063
Total
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(167,370)	(93,687)	(188,923)	16,093
Other comprehensive income (loss) before reclassification	(10,674)	(65,179)	10,493	(174,986)
Amounts reclassified from accumulated other comprehensive income (loss)	399	332	785	359
Net current period other comprehensive (loss) income	(10,275)	(64,847)	11,278	(174,627)
Ending balance	(177,645)	(158,534)	(177,645)	(158,534)
Unrealized Gains and Losses on Available- for-Sales Securities
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(166,612)	(92,751)	(188,154)	17,056
Other comprehensive income (loss) before reclassification	(10,674)	(65,179)	10,493	(174,986)
Amounts reclassified from accumulated other comprehensive income (loss)	388	305	763	305
Net current period other comprehensive (loss) income	(10,286)	(64,874)	11,256	(174,681)
Ending balance	(176,898)	(157,625)	(176,898)	(157,625)
Defined Benefit Pension Items
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(758)	(936)	(769)	(963)
Other comprehensive income (loss) before reclassification	0	0	0	0
Amounts reclassified from accumulated other comprehensive income (loss)	11	27	22	54
Net current period other comprehensive (loss) income	11	27	22	54
Ending balance	$ (747)	$ (909)	$ (747)	$ (909)