Federal Home Loan Bank Advances (FY) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
FHLB Advances [Abstract]
Average balance outstanding during the year		$ 77,049	$ 74,729
Maximum amount outstanding at any month-end during the year		84,000	98,000
Balance outstanding at end of year	$ 115,500	$ 84,000	$ 70,000
Weighted average interest rate at end of year	1.85%	2.32%	2.51%
Average cost of advances during the year		2.42%	2.13%
Weighted average contractual maturity	28 months	18 months	24 months
General borrowing limit		30.00%
FHLB advances, remaining amount available to borrow		$ 59,400
FHLB Maturity [Abstract]
2020		33,500
2021		22,500
2022		18,000
2023		5,000
2024		5,000
Total	$ 115,500	84,000	$ 70,000
First Mortgage Loans [Member]
FHLB Advances [Abstract]
FHLB advances, collateral real estate loans		$ 156,100	$ 151,000

Amount of maximum advances or credit lines available as percentage of assets from the Federal Home Loan Bank (FHLB).

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Amount of borrowings as of the balance sheet date from the Federal Home Loan Bank, which are primarily used to cover shortages in the required reserve balance and liquidity shortages.

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The calculated average balance outstanding for the year for all Federal Home Loan Bank advances as of the Balance Sheet date.

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-Publisher FASB
-Name Accounting Standards Codification
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The calculated weighted average interest rate for Federal Home Loan Bank advances for the period ended as of the Balance Sheet date.

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The maximum balance outstanding at any month end during the period as of the Balance Sheet date.

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Amount of advances or credit lines available from the Federal Home Loan Bank (FHLB).

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Amount of advance from Federal Home Loan Bank (FHLBank) maturing in fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of advance from Federal Home Loan Bank (FHLBank) maturing in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of advance from Federal Home Loan Bank (FHLBank) maturing in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of advance from Federal Home Loan Bank (FHLBank) maturing in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of advance from Federal Home Loan Bank (FHLBank) maturing in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Maturity period on fixed rate advances made and reported by Federal Home Loan Bank (FHLBank), in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average interest rate on advances made and reported by Federal Home Loan Bank (FHLBank).

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The carrying amount, as of the date of the latest financial statement presented, of loans receivable which are owned but transferred to serve as collateral for the payment of FHLB debt obligations, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.

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