SHORT-TERM BORROWINGS AND LONG-TERM DEBT - Narrative (Details)	1 Months Ended		3 Months Ended
	Dec. 31, 2004 USD ($)	Sep. 30, 2004 USD ($)	Mar. 31, 2026 USD ($) period	Dec. 31, 2025 USD ($)
Debt Instrument [Line Items]
Long term borrowings			$ 76,547,000	$ 76,547,000
Investment securities			1,333,704,000	1,310,603,000
Junior subordinated debentures
Debt Instrument [Line Items]
Long term borrowings			$ 51,547,000	51,547,000
Number of periods interest can be deferred | period			20
C P B Capital Trust I V
Debt Instrument [Line Items]
Trust preferred securities issued value		$ 30,000,000.0
Common securities issued to company		$ 900,000
C P B Capital Trust I V | Junior subordinated debentures
Debt Instrument [Line Items]
Long term borrowings			$ 30,900,000
C P B Capital Trust V
Debt Instrument [Line Items]
Trust preferred securities issued value	$ 20,000,000.0
Common securities issued to company	$ 600,000
C P B Capital Trust V | Junior subordinated debentures
Debt Instrument [Line Items]
Long term borrowings			$ 20,600,000
Maximum | Junior subordinated debentures
Debt Instrument [Line Items]
Redemption period			90 days
Federal Home Loan Bank Borrowings
Debt Instrument [Line Items]
Line of Credit, maximum borrowing capacity			$ 1,820,000,000	1,800,000,000
Unused borrowings available			1,700,000,000	1,680,000,000
FHLB advances and other short-term borrowings			0	0
Long term borrowings			$ 25,000,000.0	$ 25,000,000.0
Long term borrowings, interest rate			4.02%	4.02%
Letters of Credit, outstanding			$ 95,600,000	$ 95,600,000
Federal Home Loan Bank Borrowings | Asset Pledged as Collateral
Debt Instrument [Line Items]
Net loans and leases			2,800,000,000	2,760,000,000
Federal Reserve discount window line of credit
Debt Instrument [Line Items]
Unused borrowings available			204,400,000	206,400,000
Federal Reserve discount window line of credit | Asset Pledged as Collateral
Debt Instrument [Line Items]
Net loans and leases			97,600,000	98,900,000
Investment securities			169,100,000	172,000,000.0
Pacific Coast Bankers' Bank ("PCBB")
Debt Instrument [Line Items]
Unused borrowings available			$ 75,000,000.0	$ 75,000,000.0
Trust IV | Junior Subordinated Debt
Debt Instrument [Line Items]
Basis spread on variable rate		2.45%
Trust V | Junior Subordinated Debt
Debt Instrument [Line Items]
Basis spread on variable rate	1.87%