Investment Company, Financial Commitment to Investee, Unrealized Appreciation (Depreciation)

No definition available.

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Namespace Prefix:	fsk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of financial support to be provided in future by investment company to investee.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 20
-Section 50
-Paragraph 16
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=66023616&loc=SL35737436-115832

+ Details

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

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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

- 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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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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

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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Commitment and Contingencies - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Aug. 09, 2018
Letter of Credit \| Senior Secured Revolving Credit Facility \| Line of Credit
Other Commitments [Line Items]
Amount outstanding	$ 175.0		$ 175.0
Letters of credit	12.0
Debt Securities, Revolving Credit Facility
Other Commitments [Line Items]
Unfunded commitments	411.9
Debt Securities, Delayed Draw Term Loan
Other Commitments [Line Items]
Unfunded commitments	540.5
Debt Securities
Other Commitments [Line Items]
Unfunded commitments	952.4	$ 1,724.1
Unrealized appreciation (depreciation) on unfunded commitments	(21.3)
Partnership Interest \| Credit Opportunities Partners JV, LLC
Other Commitments [Line Items]
Unfunded commitments	$ 560.2	$ 350.2