Loans Receivable - SBA Loans (Details) - SBA Loans - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SBA Loans [Line Items]
Loans serviced for others with participating interest, gross loan balance	$ 32,131	$ 40,616
SBA loans serviced for others with participating interest, participation balance owned by Bank	7,842	9,850
Servicing fee income and fees from SBA loans serviced for others	$ 423	$ 532	$ 506

Amount of derecognized financial assets from transactions which comprise an initial transfer and an agreement entered into in contemplation of the initial transfer resulting in retention of substantially all of the exposure to the economic return throughout the term of the transaction, at the date of derecognition.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4D
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121570589&loc=SL51823488-111719

Name:	us-gaap_TransferOfFinancialAssetsAccountedForAsSalesAmountDerecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant