Loans and Leases - Additional Commitments to Existing Customers with Restructured Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Receivables [Abstract]
Additional Commitments To Financing Receivable Modifications Amount	$ 37	$ 1,834

The amount of committed additional loan amount after modification of trouble debt restructuring of loan.

No definition available.

Name:	bsrr_AdditionalCommitmentsToFinancingReceivableModificationsAmount
Namespace Prefix:	bsrr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant