INVESTMENT SECURITIES - Summary of Amortized Cost and Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Securities held-to-maturity:
Amortized Cost	$ 329,272	$ 0
Gross Unrealized Gains	0
Gross Unrealized Losses	(43,600)
Fair Value	285,672
Securities available-for-sale:
Amortized Cost	896,956	1,304,723
Gross Unrealized Gains	1,231	18,324
Gross Unrealized Losses	(32,752)	(7,344)
Securities available-for-sale, at fair value	865,435	1,315,703
U.S. government agency and U.S. government sponsored enterprise residential mortgage-backed securities
Securities held-to-maturity:
Amortized Cost	153,621
Gross Unrealized Gains	0
Gross Unrealized Losses	(18,334)
Fair Value	135,287
Securities available-for-sale:
Amortized Cost	12,051	190,382
Gross Unrealized Gains	0	2,898
Gross Unrealized Losses	(686)	(1,311)
Securities available-for-sale, at fair value	11,365	191,969
U.S. government agency and U.S. government sponsored enterprise collateralized mortgage obligations
Securities held-to-maturity:
Amortized Cost	61,447
Gross Unrealized Gains	0
Gross Unrealized Losses	(8,051)
Fair Value	53,396
Securities available-for-sale:
Amortized Cost	160,657	242,458
Gross Unrealized Gains	258	1,171
Gross Unrealized Losses	(6,862)	(2,088)
Securities available-for-sale, at fair value	154,053	241,541
Municipal securities
Securities held-to-maturity:
Amortized Cost	114,204
Gross Unrealized Gains	0
Gross Unrealized Losses	(17,215)
Fair Value	96,989
Securities available-for-sale:
Amortized Cost		117,913
Gross Unrealized Gains		2,641
Gross Unrealized Losses		(1,539)
Securities available-for-sale, at fair value		119,015
SBA loan pool securities
Securities available-for-sale:
Amortized Cost	13,085	14,679
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(23)	(88)
Securities available-for-sale, at fair value	13,062	14,591
Non-agency residential mortgage-backed securities
Securities available-for-sale:
Amortized Cost	53,122	56,014
Gross Unrealized Gains	0	11
Gross Unrealized Losses	(7,641)	0
Securities available-for-sale, at fair value	45,481	56,025
Collateralized loan obligations
Securities available-for-sale:
Amortized Cost	492,775	521,275
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(14,572)	(2,311)
Securities available-for-sale, at fair value	478,203	518,964
Corporate debt securities
Securities available-for-sale:
Amortized Cost	165,266	162,002
Gross Unrealized Gains	973	11,603
Gross Unrealized Losses	(2,968)	(7)
Securities available-for-sale, at fair value	$ 163,271	$ 173,598

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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