Debt Instrument, Number Of Scheduled Pooling Dates

No definition available.

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- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI https://asc.fasb.org/extlink&oid=123466204&loc=SL6031897-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI https://asc.fasb.org/extlink&oid=126734703&loc=d3e572229-122910

Reference 3: 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(22))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI https://asc.fasb.org/extlink&oid=126897435&loc=d3e534808-122878

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
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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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Weighted average interest rate of long-term debt outstanding calculated over time.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Details

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- Details

Name:	us-gaap_DebtInstrumentAxis=cswc_SmallBusinessAdministrationDebenturesMember
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- Details

Name:	us-gaap_DebtInstrumentAxis=cswc_SmallBusinessAdministrationDebenturesDueSeptember2031Member
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Balance Type:
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- Details

Name:	us-gaap_DebtInstrumentAxis=cswc_SmallBusinessAdministrationDebenturesDueMarch2032Member
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- Details

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- Details

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- Details

Name:	us-gaap_DebtInstrumentAxis=cswc_SmallBusinessAdministrationDebenturesHeldInPoolMember
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BORROWINGS - Schedule of Issued and Outstanding SBA Debentures (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2022 USD ($) poolingDate	Dec. 31, 2021	Dec. 31, 2022 USD ($) poolingDate	Dec. 31, 2021	Mar. 31, 2022 USD ($)
Debt Instrument [Line Items]
Outstanding Balance	$ 619,000		$ 619,000		$ 535,000
Unsecured Debt \| SBA Debentures
Debt Instrument [Line Items]
Outstanding Balance	$ 104,000		$ 104,000		$ 40,000
Number of pooling date \| poolingDate	2		2
Weighted-average interest rate	3.70%	1.43%	2.98%	1.24%
Unsecured Debt \| Debentures due September 2031
Debt Instrument [Line Items]
Fixed Interest Rate	1.575%		1.575%
Outstanding Balance	$ 15,000		$ 15,000
Unsecured Debt \| Debentures due March 2032
Debt Instrument [Line Items]
Fixed Interest Rate	3.209%		3.209%
Outstanding Balance	$ 25,000		$ 25,000
Unsecured Debt \| Debentures due January 2032
Debt Instrument [Line Items]
Fixed Interest Rate	4.533%		4.533%
Outstanding Balance	$ 40,000		$ 40,000
Secured Debt \| Debentures not pooled
Debt Instrument [Line Items]
Outstanding Balance	$ 24,000		$ 24,000
Weighted-average interest rate			5.14%