Financing receivable asset specific allowance.

No definition available.

Name:	ck0001690012_FinancingReceivableAssetSpecificAllowance
Namespace Prefix:	ck0001690012_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Mortgage loans on real estate, outstanding.

+ References

No definition available.

+ Details

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Namespace Prefix:	ck0001690012_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Risk rating for commercial mortgage loans held for investment and real estate securities.

+ References

No definition available.

+ Details

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Namespace Prefix:	ck0001690012_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Maturity date of mortgage loan within investment in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate, in YYYY-MM-DD format.

+ References

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+ Details

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Namespace Prefix:	srt_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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+ Details

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Period Type:	duration

- Definition

The cash outflow from the repayment of a long-term debt instrument issued, secured by a first mortgage deed of trust, containing a pledge of real property. The lender has the highest claim on the property in case of default.

+ References

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-Topic 230
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-Section 45
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-Subparagraph (b)
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+ Details

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Period Type:	duration

- Details

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Namespace Prefix:
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Balance Type:
Period Type:

- Details

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Period Type:

- Details

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Namespace Prefix:
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- Details

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Commercial Mortgage Loans Held for Investment - Schedule of asset specific Cecl reserve (Parenthetical) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2026 USD ($) Rating	Mar. 31, 2025 USD ($)	Dec. 31, 2025 USD ($)
Mortgage Loans On Real Estate [Line Items]
Asset specific CECL reserve	$ 4,173	$ 8,180	$ 942
Honolulu, HI Loan [Member]
Mortgage Loans On Real Estate [Line Items]
Principal balance paid down		$ 750
Converse TX Loan [Member]
Mortgage Loans On Real Estate [Line Items]
Mortgage loans on real estate, amortized cost	$ 24,946
Mortgage loans on real estate maturity date	May 09, 2026
Risk rating for commercial mortgage loans held for investment and real estate securities \| Rating	4
Asset specific CECL reserve	$ 3,615
Garland TX Loan [Member]
Mortgage Loans On Real Estate [Line Items]
Mortgage loans on real estate, amortized cost	$ 20,102
Mortgage loans on real estate maturity date	May 09, 2026
Risk rating for commercial mortgage loans held for investment and real estate securities \| Rating	4
Asset specific CECL reserve	$ 558
Garland TX Loan [Member] \| Unfunded Loan Commitments
Mortgage Loans On Real Estate [Line Items]
Mortgage loans on real estate, amortized cost	$ 598