LOANS - Narrative (Details)			3 Months Ended		9 Months Ended		12 Months Ended
	Jan. 01, 2023 USD ($)	Aug. 01, 2022 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($) tdr	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($) tdr	Sep. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)	Mar. 31, 2023 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, accrued interest, before allowance for credit loss			$ 22,400,000		$ 22,400,000		$ 22,400,000	$ 18,000,000
Amortized cost, PCD loans			60,600,000		60,600,000		60,600,000	24,000,000
PCD loans, estimated ACL			3,800,000		3,800,000		3,800,000	1,700,000
Total TDRs								21,751,000
Additional amount committed on TDR loans								0
Allowance for TDRs								841,000
Modifications, number of contracts | tdr				0		0
Subsequent default, number of contracts | tdr						0
Total loans, other financial institutions			286,900,000		286,900,000		286,900,000	202,600,000
Loans sold to other financial institutions			165,600,000		165,600,000		165,600,000	100,100,000
Loans purchased			121,300,000		$ 121,300,000		121,300,000	102,500,000
LGD Rate					15.00%
Threshold default percentage					1.00%
Provision for credit losses, LHFI			1,000,000	$ 4,300,000	$ 12,500,000	$ 4,750,000		3,900,000
Loans held for investment			5,089,800,000	$ 3,719,000,000	5,089,800,000	3,719,000,000	5,089,800,000	3,774,157,000
Increase (decrease) in loans held for investment							$ 1,370,000,000
Increase (decrease) in loans held for investment, percent							36.80%
Initial allowance on PCD loans								3,176,000		$ 1,303,000	$ 1,303,000
Provision for credit loss					13,250,000	$ 4,900,000
Heritage Southeast Bank
Accounts, Notes, Loans and Financing Receivable [Line Items]
Business combination, acquired receivable, fair value	$ 1,091,000,000.000
Discount (premium) on loans acquired	33,700,000
Gross contractual amounts receivable	1,125,000,000
Contractual cash flows not expected to be collected	16,500,000
Provision for credit losses, LHFI					10,700,000
Business combination, loans	1,155,712,000		1,159,000,000		1,159,000,000		$ 1,159,000,000
Initial allowance on PCD loans									$ 3,200,000
Provision for credit loss	$ 3,200,000
Beach Bancorp
Accounts, Notes, Loans and Financing Receivable [Line Items]
Business combination, acquired receivable, fair value		$ 460,000,000
Discount (premium) on loans acquired		8,800,000
Gross contractual amounts receivable		468,800,000
Contractual cash flows not expected to be collected		6,400,000
TDRs acquired		1,500,000
Business combination, loans		482,903,000	$ 485,171,000		$ 485,171,000		$ 485,171,000
Initial allowance on PCD loans								$ 1,300,000
Provision for credit loss		$ 1,300,000