Loans and Allowance - Allowance for Credit Losses (Details) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2021 USD ($) borrower	Mar. 31, 2020 USD ($) borrower	Dec. 31, 2020 USD ($)
LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES
Average loans	$ 248,920	$ 281,335
Net charge-offs to average loans (annualized)	(0.44%)	0.10%
Number of borrowers \| borrower	8	14
Loans charged off	$ 81	$ 125	$ 392
Outstanding commitments	31,800	31,200
Unfunded commitments
Beginning balance	33	37	37
Impact of ASC 326 adoption	457
Reduction of unfunded reserve	(12)
Provisions charged to operations		13
Ending balance	$ 478	$ 50	$ 33

Amount of writeoff of financing receivable, charged against allowance for credit loss.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(3)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 55
-Paragraph 79
-URI http://asc.fasb.org/extlink&oid=121647567&loc=SL82922352-210448

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration