ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2022	Jun. 30, 2021
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance	$ 1,155,287	$ 1,192,620	$ 1,172,824	$ 701,096	$ 1,192,620	$ 701,096
Total other comprehensive (loss) income, net of tax	(20,570)	(43,199)	4,045	6,455	(63,769)	10,500
Balance	1,140,522	1,155,287	1,204,276	1,172,824	1,140,522	1,204,276
Accumulated Other Comprehensive (Loss) Income
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance	(49,380)	(6,181)	531	(5,924)	(6,181)	(5,924)
Other comprehensive (loss) income before reclassifications					(63,156)	11,310
Amounts reclassified from accumulated other comprehensive loss					(613)	(810)
Total other comprehensive (loss) income, net of tax	(20,570)	(43,199)	4,045	6,455	(63,769)	10,500
Balance	(69,950)	(49,380)	4,576	531	(69,950)	4,576
Securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance		(7,864)		12,694	(7,864)	12,694
Other comprehensive (loss) income before reclassifications					(70,803)	(4,451)
Amounts reclassified from accumulated other comprehensive loss					685	(812)
Total other comprehensive (loss) income, net of tax					(70,118)	(5,263)
Balance	(77,982)		7,431		(77,982)	7,431
Defined Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance		(1,306)		(6,086)	(1,306)	(6,086)
Other comprehensive (loss) income before reclassifications					1,368	2,061
Amounts reclassified from accumulated other comprehensive loss					(1,282)	(579)
Total other comprehensive (loss) income, net of tax					86	1,482
Balance	(1,220)		(4,604)		(1,220)	(4,604)
Derivatives
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance		$ 2,989		$ (12,532)	2,989	(12,532)
Other comprehensive (loss) income before reclassifications					6,279	13,700
Amounts reclassified from accumulated other comprehensive loss					(16)	581
Total other comprehensive (loss) income, net of tax					6,263	14,281
Balance	$ 9,252		$ 1,749		$ 9,252	$ 1,749