INVESTMENT SECURITIES - Continuous Unrealized Loss on Investment (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
AFS
AFS, Less than 12 months, Gross unrealized losses	$ (120,581)	$ (2,503)
AFS, Less than 12 months, Fair value	1,173,366	181,901
AFS, Twelve months or more, Gross unrealized losses	(18,941)	(822)
AFS, Twelve months or more, Fair value	73,529	15,712
AFS, Total, Gross unrealized losses	(139,522)	(3,325)
AFS, Total, Fair value	1,246,895	197,613
Residential mortgage-backed securities
AFS
AFS, Less than 12 months, Gross unrealized losses	(9,164)	(38)
AFS, Less than 12 months, Fair value	195,834	5,324
AFS, Twelve months or more, Gross unrealized losses	(653)	(300)
AFS, Twelve months or more, Fair value	1,964	2,406
AFS, Total, Gross unrealized losses	(9,817)	(338)
AFS, Total, Fair value	197,798	7,730
Commercial mortgage-backed securities
AFS
AFS, Less than 12 months, Gross unrealized losses	(9,182)	(235)
AFS, Less than 12 months, Fair value	56,380	18,127
AFS, Twelve months or more, Gross unrealized losses	(652)	0
AFS, Twelve months or more, Fair value	2,476	0
AFS, Total, Gross unrealized losses	(9,834)	(235)
AFS, Total, Fair value	58,856	18,127
Residential collateralized mortgage obligations
AFS
AFS, Less than 12 months, Gross unrealized losses	(29,963)	(1,007)
AFS, Less than 12 months, Fair value	407,507	53,068
AFS, Twelve months or more, Gross unrealized losses	(6,058)	(314)
AFS, Twelve months or more, Fair value	22,157	7,116
AFS, Total, Gross unrealized losses	(36,021)	(1,321)
AFS, Total, Fair value	429,664	60,184
Commercial collateralized mortgage obligations
AFS
AFS, Less than 12 months, Gross unrealized losses	(5,731)	(135)
AFS, Less than 12 months, Fair value	83,623	14,806
AFS, Twelve months or more, Gross unrealized losses	(1,294)	(198)
AFS, Twelve months or more, Fair value	7,238	5,132
AFS, Total, Gross unrealized losses	(7,025)	(333)
AFS, Total, Fair value	90,861	19,938
Municipal bonds
AFS
AFS, Less than 12 months, Gross unrealized losses	(62,825)	(914)
AFS, Less than 12 months, Fair value	391,637	64,237
AFS, Twelve months or more, Gross unrealized losses	(7,764)	(10)
AFS, Twelve months or more, Fair value	24,560	1,058
AFS, Total, Gross unrealized losses	(70,589)	(924)
AFS, Total, Fair value	416,197	65,295
HTM
HFM, Less than 12 months, Gross unrealized losses	(101)
HFM, Less than 12 months, Fair value	2,998
HFM, 12 months or more, Gross unrealized losses	0
HFM, 12 months or more, Fair value	0
HFM, Total, Gross unrealized losses	(101)
HTM, Total, Fair value	2,998
Corporate debt securities
AFS
AFS, Less than 12 months, Gross unrealized losses	(2,971)	(1)
AFS, Less than 12 months, Fair value	33,692	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	(2,971)	(1)
AFS, Total, Fair value	33,692	3,164
U.S. Treasury securities
AFS
AFS, Less than 12 months, Gross unrealized losses	(745)	(173)
AFS, Less than 12 months, Fair value	4,693	23,175
AFS, Twelve months or more, Gross unrealized losses	(2,520)	0
AFS, Twelve months or more, Fair value	15,134	0
AFS, Total, Gross unrealized losses	(3,265)	(173)
AFS, Total, Fair value	$ 19,827	$ 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 amortized cost (held-to-maturity), in continuous loss position for 12 months or longer.

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