Loans Receivable Held for Investment, Recorded Investment in Non-accrual Loans by Loan Type (Q3) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Loans Receivable Held for Investment [Abstract]
Total non-accrual loans	$ 820	$ 424	$ 911
Loans 90 days or more delinquent that were accruing interest	0	0	0
Real Estate [Member] \| Single Family [Member]
Loans Receivable Held for Investment [Abstract]
Total non-accrual loans	8	18
Real Estate [Member] \| Church [Member]
Loans Receivable Held for Investment [Abstract]
Total non-accrual loans	$ 812	$ 406	$ 911

Amount of financing receivable 90 days or more past due and still accruing.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 16
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919258-210447

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5111-111524

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 55
-Paragraph 80
-URI http://asc.fasb.org/extlink&oid=121647567&loc=SL82922355-210448

Name:	us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant