SHAREHOLDERS' EQUITY AND EARNINGS PER COMMON SHARE - Accumulated Other Comprehensive (Loss) Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total shareholders’ equity	$ 1,182,435	$ 1,187,773	$ 1,758,564	$ 1,552,918
Net of Tax	(34,114)	18,874	25,507
Net of Tax	0	(4)	44
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent	(45,801)	25,237	34,260
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	11,687	(6,359)	(8,797)
Total other comprehensive (loss)/income	(34,114)	18,878	25,463
Accumulated other comprehensive (loss)/income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total shareholders’ equity	(3,243)	30,871	11,993	(13,470)
Total other comprehensive (loss)/income	(34,114)	18,878	25,463
Net unrealized holding (loss)/gain on AFS securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI attributable to parent, before tax	(1,806)	44,988
Income taxes related to items of accumulated other comprehensive (loss)/income:	407	(11,530)
Total shareholders’ equity	(1,398)	33,459	14,204	(11,453)
Before Tax	(46,794)	25,721	34,591
Other Comprehensive Income (Loss) before Reclassifications, Tax	11,937	(6,470)	(8,890)
Net of Tax	(34,857)	19,251	25,701
Before Tax	0	(5)	61
Tax Effect	0	1	(17)
Net of Tax	0	(4)	44
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent	(46,794)	25,726	34,530
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	11,937	(6,471)	(8,873)
Total other comprehensive (loss)/income	(34,857)	19,255	25,657
Net unrealized holding (loss) on pension plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI attributable to parent, before tax	(2,518)	(3,511)
Income taxes related to items of accumulated other comprehensive (loss)/income:	674	924
Total shareholders’ equity	(1,845)	(2,588)	(2,211)	$ (2,017)
Before Tax	993	(489)	(270)
Other Comprehensive Income (Loss) before Reclassifications, Tax	(250)	112	76
Net of Tax	743	(377)	(194)
Before Tax	0	0	0
Tax Effect	0	0	0
Net of Tax	0	0	0
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent	993	(489)	(270)
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	(250)	112	76
Total other comprehensive (loss)/income	$ 743	$ (377)	$ (194)