Revenue From Contracts With Customers - Contract Balances (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2026	Dec. 31, 2025
Statement of Financial Position [Abstract]
Receivables, which are included in "Other assets"	$ 1,766	$ 2,147
Contract liabilities, which are included in "Accrued interest payable and other liabilities"	$ 261	$ 279

Contract With Customer, Liabilities Reclassified to Other Assets

No definition available.

Name:	banc_ContractWithCustomerLiabilitiesReclassifiedtoOtherAssets
Namespace Prefix:	banc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration