INVESTMENT SECURITIES - Continuous Unrealized Loss on Investment (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
AFS
AFS, Less than 12 months, Gross unrealized losses	$ (38,540)	$ (2,503)
AFS, Less than 12 months, Fair value	779,641	181,901
AFS, Twelve months or more, Gross unrealized losses	(5,421)	(822)
AFS, Twelve months or more, Fair value	43,297	15,712
AFS, Total, Gross unrealized losses	(43,961)	(3,325)
AFS, Total, Fair value	822,938	197,613
Residential mortgage-backed securities
AFS
AFS, Less than 12 months, Gross unrealized losses	(1,064)	(38)
AFS, Less than 12 months, Fair value	25,716	5,324
AFS, Twelve months or more, Gross unrealized losses	(444)	(300)
AFS, Twelve months or more, Fair value	2,233	2,406
AFS, Total, Gross unrealized losses	(1,508)	(338)
AFS, Total, Fair value	27,949	7,730
Commercial mortgage-backed securities
AFS
AFS, Less than 12 months, Gross unrealized losses	(3,958)	(235)
AFS, Less than 12 months, Fair value	58,243	18,127
AFS, Twelve months or more, Gross unrealized losses	0	0
AFS, Twelve months or more, Fair value	0	0
AFS, Total, Gross unrealized losses	(3,958)	(235)
AFS, Total, Fair value	58,243	18,127
Residential collateralized mortgage obligations
AFS
AFS, Less than 12 months, Gross unrealized losses	(7,475)	(1,007)
AFS, Less than 12 months, Fair value	177,481	53,068
AFS, Twelve months or more, Gross unrealized losses	(2,465)	(314)
AFS, Twelve months or more, Fair value	21,315	7,116
AFS, Total, Gross unrealized losses	(9,940)	(1,321)
AFS, Total, Fair value	198,796	60,184
Commercial collateralized mortgage obligations
AFS
AFS, Less than 12 months, Gross unrealized losses	(2,802)	(135)
AFS, Less than 12 months, Fair value	103,919	14,806
AFS, Twelve months or more, Gross unrealized losses	(622)	(198)
AFS, Twelve months or more, Fair value	7,608	5,132
AFS, Total, Gross unrealized losses	(3,424)	(333)
AFS, Total, Fair value	111,527	19,938
Municipal bonds
AFS
AFS, Less than 12 months, Gross unrealized losses	(21,126)	(914)
AFS, Less than 12 months, Fair value	375,801	64,237
AFS, Twelve months or more, Gross unrealized losses	(1,890)	(10)
AFS, Twelve months or more, Fair value	12,141	1,058
AFS, Total, Gross unrealized losses	(23,016)	(924)
AFS, Total, Fair value	387,942	65,295
HTM
HFM, Less than 12 months, Gross unrealized losses	(17)
HFM, Less than 12 months, Fair value	2,474
HFM, 12 months or more, Gross unrealized losses	0
HFM, 12 months or more, Fair value	0
HFM, Total, Gross unrealized losses	(17)
HTM, Total, Fair value	2,474
Corporate debt securities
AFS
AFS, Less than 12 months, Gross unrealized losses	(574)	(1)
AFS, Less than 12 months, Fair value	16,758	3,164
AFS, Twelve months or more, Gross unrealized losses	0	0
AFS, Twelve months or more, Fair value	0	0
AFS, Total, Gross unrealized losses	(574)	(1)
AFS, Total, Fair value	16,758	3,164
U.S. Treasury securities
AFS
AFS, Less than 12 months, Gross unrealized losses	(1,541)	(173)
AFS, Less than 12 months, Fair value	21,723	23,175
AFS, Twelve months or more, Gross unrealized losses	0	0
AFS, Twelve months or more, Fair value	0	0
AFS, Total, Gross unrealized losses	(1,541)	(173)
AFS, Total, Fair value	$ 21,723	$ 23,175

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position without allowance for credit loss.

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Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in continuous loss position for 12 months or longer.

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