Fair Value Measurements Assets and Liabilities Measured and Recorded (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity Securities, FV-NI	$ 2	$ 3
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	2,454,058	2,246,839
Other Borrowings, Fair Value Disclosure	113,634	118,838
Credit-Link Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Borrowings, Fair Value Disclosure	113,634	118,838	$ 123,116	$ 132,030
Fair Value, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash Flow Hedge Derivative Instrument Assets at Fair Value	4,065
Warrants Not Settleable in Cash, Fair Value Disclosure	3,437	3,763
Cash Flow Hedge Derivative Instrument Liabilities at Fair Value		1,442
Derivative Liability, Fair Value of Collateral	4,156	7,562
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	2,454,058
Fair Value, Recurring \| Government agency and government-sponsored enterprise pass through securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	834,085	861,840
Fair Value, Recurring \| Commercial Mortgage Backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	50,966	51,564
Fair Value, Recurring \| Government agency and government-sponsored enterprise collateralized mortgage obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	871,624	446,631
Fair Value, Recurring \| Municipal Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)		594
Fair Value, Recurring \| Corporate Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	241,596	257,712
Fair Value, Recurring \| Private Label Collateralized Mortgage Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	228,975	316,910
Fair Value, Recurring \| Collateralized Loan Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	200,822	279,416
Fair Value, Recurring \| Mortgage-backed Securities, Issued by Private Enterprises
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	9,279	12,372
Fair Value, Recurring \| Asset-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	13,249	15,600
Fair Value, Recurring \| SBA asset-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	3,462	4,200
Level 1 \| Fair Value, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash Flow Hedge Derivative Instrument Assets at Fair Value	0
Warrants Not Settleable in Cash, Fair Value Disclosure	0	0
Cash Flow Hedge Derivative Instrument Liabilities at Fair Value		0
Derivative Liability, Fair Value of Collateral	0	0
Equity Securities, FV-NI	2	3
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	0	0
Other Borrowings	0	0
Level 1 \| Fair Value, Recurring \| Government agency and government-sponsored enterprise pass through securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	0	0
Level 1 \| Fair Value, Recurring \| Commercial Mortgage Backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	0	0
Level 1 \| Fair Value, Recurring \| Government agency and government-sponsored enterprise collateralized mortgage obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	0	0
Level 1 \| Fair Value, Recurring \| Municipal Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)		0
Level 1 \| Fair Value, Recurring \| Corporate Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	0	0
Level 1 \| Fair Value, Recurring \| Private Label Collateralized Mortgage Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	0	0
Level 1 \| Fair Value, Recurring \| Collateralized Loan Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	0	0
Level 1 \| Fair Value, Recurring \| Mortgage-backed Securities, Issued by Private Enterprises
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	0	0
Level 1 \| Fair Value, Recurring \| Asset-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	0	0
Level 1 \| Fair Value, Recurring \| SBA asset-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	0	0
Level 2 \| Fair Value, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash Flow Hedge Derivative Instrument Assets at Fair Value	4,065
Warrants Not Settleable in Cash, Fair Value Disclosure	0	0
Cash Flow Hedge Derivative Instrument Liabilities at Fair Value		1,442
Derivative Liability, Fair Value of Collateral	4,156	7,562
Equity Securities, FV-NI	0	0
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	2,451,688	2,244,709
Other Borrowings	0	0
Level 2 \| Fair Value, Recurring \| Government agency and government-sponsored enterprise pass through securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	834,085	861,840
Level 2 \| Fair Value, Recurring \| Commercial Mortgage Backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	50,966	51,564
Level 2 \| Fair Value, Recurring \| Government agency and government-sponsored enterprise collateralized mortgage obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	871,624	446,631
Level 2 \| Fair Value, Recurring \| Municipal Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)		594
Level 2 \| Fair Value, Recurring \| Corporate Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	239,226	255,582
Level 2 \| Fair Value, Recurring \| Private Label Collateralized Mortgage Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	228,975	316,910
Level 2 \| Fair Value, Recurring \| Collateralized Loan Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	200,822	279,416
Level 2 \| Fair Value, Recurring \| Mortgage-backed Securities, Issued by Private Enterprises
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	9,279	12,372
Level 2 \| Fair Value, Recurring \| Asset-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	13,249	15,600
Level 2 \| Fair Value, Recurring \| SBA asset-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	3,462	4,200
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Warrants Not Settleable in Cash, Fair Value Disclosure	3,437	3,763	$ 3,689	$ 4,048
Level 3 \| Fair Value, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash Flow Hedge Derivative Instrument Assets at Fair Value	0
Warrants Not Settleable in Cash, Fair Value Disclosure	3,437	3,763
Cash Flow Hedge Derivative Instrument Liabilities at Fair Value		0
Derivative Liability, Fair Value of Collateral	0	0
Equity Securities, FV-NI	0	0
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	2,370	2,130
Other Borrowings	113,634	118,838
Level 3 \| Fair Value, Recurring \| Government agency and government-sponsored enterprise pass through securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	0	0
Level 3 \| Fair Value, Recurring \| Commercial Mortgage Backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	0	0
Level 3 \| Fair Value, Recurring \| Government agency and government-sponsored enterprise collateralized mortgage obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	0	0
Level 3 \| Fair Value, Recurring \| Municipal Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)		0
Level 3 \| Fair Value, Recurring \| Corporate Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	2,370	2,130
Level 3 \| Fair Value, Recurring \| Private Label Collateralized Mortgage Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	0	0
Level 3 \| Fair Value, Recurring \| Collateralized Loan Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	0	0
Level 3 \| Fair Value, Recurring \| Mortgage-backed Securities, Issued by Private Enterprises
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	0	0
Level 3 \| Fair Value, Recurring \| Asset-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	0	0
Level 3 \| Fair Value, Recurring \| SBA asset-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
(amortized cost of $2,646,414 and $2,526,644, respectively)(ACL of $775 and $—, respectively)	$ 0	$ 0

BANC OF CALIFORNIA, INC. 10-K