Line of credit carrying value.

No definition available.

Name:	ck0001849894_LineOfCreditCarryingValue
Namespace Prefix:	ck0001849894_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

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-Section S99
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+ Details

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Date the credit facility terminates, in YYYY-MM-DD format.

+ References

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-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
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+ Details

Name:	us-gaap_LineOfCreditFacilityExpirationDate1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

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+ Details

Name:	us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_CreditFacilityAxis=ck0001849894_SPVIFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=ck0001849894_SpvIiFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_CollateralizedDebtObligationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=ck0001849894_SubscriptionFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=ck0001849894_LoanRepurchaseObligationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ck0001849894_SeriesANotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ck0001849894_SeriesBNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ck0001849894_SeriesCNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ck0001849894_SeriesDNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Borrowings - Schedule of Outstanding Debt Obligations (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2024	Dec. 31, 2023	Apr. 18, 2024	Apr. 08, 2024	Apr. 07, 2024	Mar. 21, 2024	Sep. 08, 2023	Sep. 07, 2023	Dec. 16, 2022	Dec. 15, 2022	Dec. 21, 2021
Debt Instrument [Line Items]
Aggregate principal committed	$ 2,321,977,000	$ 1,570,025,000
Outstanding principal	2,121,977,000	1,148,025,000
Carrying value	2,101,460,000	1,134,786,000
Unused portion	200,000,000	422,000,000
SPV I Facility
Debt Instrument [Line Items]
Aggregate principal committed	550,000,000	485,000,000		$ 550,000,000	$ 485,000,000				$ 485,000,000	$ 400,000,000
Outstanding principal	550,000,000	378,000,000
Carrying value	$ 543,292,000	374,700,000
Unused portion		$ 107,000,000
Maturity date	Apr. 08, 2029	Dec. 21, 2026
SPV II Facility
Debt Instrument [Line Items]
Aggregate principal committed	$ 595,000,000	$ 445,000,000	$ 595,000,000			$ 495,000,000	$ 445,000,000	$ 370,000,000
Outstanding principal	595,000,000	295,000,000
Carrying value	$ 588,926,000	289,349,000
Unused portion		$ 150,000,000
Maturity date	Aug. 15, 2028	Aug. 15, 2028
Collateralized loan obligations
Debt Instrument [Line Items]
Aggregate principal committed	$ 390,000,000	$ 390,000,000
Outstanding principal	390,000,000	390,000,000
Carrying value	$ 386,621,000	$ 386,393,000
Maturity date	Oct. 15, 2035	Nov. 15, 2035
Subscription Facility
Debt Instrument [Line Items]
Aggregate principal committed	$ 200,000,000	$ 200,000,000									$ 200,000,000
Outstanding principal		35,000,000
Carrying value	(152,000)	34,319,000
Unused portion	$ 200,000,000	$ 165,000,000
Maturity date	Dec. 18, 2024	Dec. 18, 2024
Loan Repurchase Obligations
Debt Instrument [Line Items]
Aggregate principal committed	$ 251,977,000	$ 50,025,000
Outstanding principal	251,977,000	50,025,000
Carrying value	251,977,000	$ 50,025,000
Series A Notes
Debt Instrument [Line Items]
Aggregate principal committed	69,000,000
Outstanding principal	69,000,000
Carrying value	$ 68,134,000
Maturity date	May 09, 2027
Series B Notes
Debt Instrument [Line Items]
Aggregate principal committed	$ 75,000,000
Outstanding principal	75,000,000
Carrying value	$ 74,059,000
Maturity date	May 09, 2029
Series C Notes
Debt Instrument [Line Items]
Aggregate principal committed	$ 116,000,000
Outstanding principal	116,000,000
Carrying value	$ 114,544,000
Maturity date	May 09, 2027
Series D Notes
Debt Instrument [Line Items]
Aggregate principal committed	$ 75,000,000
Outstanding principal	75,000,000
Carrying value	$ 74,059,000
Maturity date	May 09, 2029