Deposits - Schedule of Composition of Network Deposits (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Reciprocal
CDARS	$ 46,162	$ 11,031
ICS	245,577	100,749
DDM	132,276	62,219
Total network deposits	424,015	173,999
One Way
CDARS	2,164	2,162
ICS	0	0
DDM	0	0
Total network deposits	$ 2,164	$ 2,162

Certificate of Deposit Account Registry Service, a special type of certificate of deposit whereby the participating bank accepts deposits in excess of the FDIC insured maximum and places the deposits through a network to member banks in the CDARS(R) network in increments of less than the FDIC insured maximum to provide the depositor full FDIC insurance coverage.

No definition available.

Name:	bmrc_TimeDepositsCertificateOfDepositAccountRegistryServiceCDARS
Namespace Prefix:	bmrc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant