Loans Receivable Held for Sale (FY) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Loans Receivable Held for Sale [Abstract]
Loans receivable held for sale	$ 40,653		$ 0	$ 6,231
Transfers of loans receivable held for investment to loans receivable held for sale	0	$ 10,684	10,684	0
Transfers of loans receivable held for sale to loans receivable held for investment	0	1,064	9,227	16,871
Loans originated for sale	118,626	15,182	15,182	20,288
Gain on sale of loans	199	204	204	70
Loan repayments	$ 530	$ 103
Multi-family Loans [Member]
Loans Receivable Held for Sale [Abstract]
Loans receivable held for sale			0	6,200
Transfers of loans receivable held for investment to loans receivable held for sale			10,700
Transfers of loans receivable held for sale to loans receivable held for investment			9,200	16,900
Loans originated for sale			$ 15,200	$ 20,200
Loans originated for sale, percentage			15.00%	20.00%
Loans held for sale, sold during period			$ 22,800	$ 19,300
Gain on sale of loans			204	70
Loan repayments			$ 115	$ 159

Loans held-for-sale including, but not limited to, mortgage loans and finance receivables during period.

No definition available.

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- Definition

Percentage of loans origination of mortgages that are held for sale.

+ References

No definition available.

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- Definition

The gains (losses) included in earnings that represent the difference between the sale price and the carrying value of loans and leases that were sold during the reporting period. This element refers to the gain (loss) and not to the cash proceeds of the sales. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585

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- Definition

Amount, after valuation allowance, of financing receivable held for sale and not part of disposal group. Excludes loan covered under loss sharing agreement and loan classified as investment in debt security.

+ References

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- Definition

The amount of cash paid for the origination of mortgages that are held for sale.

+ References

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- Definition

The cash inflow from collection of repayments from borrowers on loans that are held with the intention to resell in the near future; includes mortgages and other types of loans.

+ References

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- References

No definition available.

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- Definition

Value of loans held-for-sale transferred to loans held in the entity's portfolio in noncash transactions.

+ References

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- Definition

Value of loans and leases held in the entity's portfolio transferred to loans and leases held-for-sale in noncash transactions.

+ References

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