XML 69 R58.htm IDEA: XBRL DOCUMENT
v3.25.3

DIVIDENDS, DISTRIBUTIONS AND TAXABLE INCOME - Schedule of Net Investment Income Related Taxes (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2025 | Sep. 30, 2024
Current tax expense (benefit): |  |  |  |
Federal | $ (38) | $ 761 | $ 80 | $ 940
State and other | 108 | 396 | 449 | 810
Excise | (39) | 491 | 240 | 570
Total current tax expense | 31 | 1,648 | 769 | 2,320
Deferred tax expense (benefit): |  |  |  |
Federal | 474 | (245) | 1,716 | 500
State and other | (52) | (137) | 8 | (49)
Total deferred tax expense (benefit) | 422 | (382) | 1,724 | 451
Total net investment income tax provision | 453 | 1,266 | 2,493 | 2,771
Current tax expense: |  |  |  |
Federal | 0 | 0 | 0 | 205
Total current tax expense | 0 | 0 | 0 | 205
Deferred tax expense (benefit): |  |  |  |
Federal | 1,051 | 898 | (362) | 2,895
State and other | 150 | 270 | 45 | 279
Total deferred tax expense (benefit) | 1,201 | 1,168 | (317) | 3,174
Total investment valuation related income tax provision (benefit) | 1,201 | 1,168 | (317) | 3,379
Total income tax provision | $ 1,654 | $ 2,434 | $ 2,176 | $ 6,150

X
- Definition Deferred Tax Expense (Income) + References No definition available. + Details
Name: | msif_DeferredTaxExpenseIncomeAbstract
Namespace Prefix: | msif_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Investment Company, Excise Tax Expense (Benefit) + References No definition available. + Details
Name: | msif_InvestmentCompanyExciseTaxExpenseBenefit
Namespace Prefix: | msif_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Investment Company, Income Tax Expense (Benefit) + References No definition available. + Details
Name: | msif_InvestmentCompanyIncomeTaxExpenseBenefit
Namespace Prefix: | msif_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Investment Income, Operating, Deferred Federal Tax Expense (Benefit) + References No definition available. + Details
Name: | msif_InvestmentIncomeOperatingDeferredFederalTaxExpenseBenefit
Namespace Prefix: | msif_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Investment Income, Operating, Deferred State And Other Tax Expense (Benefit) + References No definition available. + Details
Name: | msif_InvestmentIncomeOperatingDeferredStateAndOtherTaxExpenseBenefit
Namespace Prefix: | msif_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Investment Income, Operating, Deferred Tax Expense (Benefit) + References No definition available. + Details
Name: | msif_InvestmentIncomeOperatingDeferredTaxExpenseBenefit
Namespace Prefix: | msif_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Investment Income, Operating, Federal Tax Expense (Benefit), Current + References No definition available. + Details
Name: | msif_InvestmentIncomeOperatingFederalTaxExpenseBenefitCurrent
Namespace Prefix: | msif_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Investment Income, Operating, State And Other Tax Expense (Benefit), Current + References No definition available. + Details
Name: | msif_InvestmentIncomeOperatingStateAndOtherTaxExpenseBenefitCurrent
Namespace Prefix: | msif_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Investment Income, Operating, Tax Expense (Benefit), Current + References No definition available. + Details
Name: | msif_InvestmentIncomeOperatingTaxExpenseBenefitCurrent
Namespace Prefix: | msif_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Investment Tax Expense (Income), Current + References No definition available. + Details
Name: | msif_InvestmentTaxExpenseIncomeCurrentAbstract
Namespace Prefix: | msif_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Investment Tax Expense (Income), Deferred + References No definition available. + Details
Name: | msif_InvestmentTaxExpenseIncomeDeferredAbstract
Namespace Prefix: | msif_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Realized Gain (Loss), Investment And Derivative, Operating, Deferred Federal Tax Expense (Benefit) + References No definition available. + Details
Name: | msif_RealizedGainLossInvestmentAndDerivativeOperatingDeferredFederalTaxExpenseBenefit
Namespace Prefix: | msif_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Realized Gain (Loss), Investment And Derivative, Operating, Deferred State And Other Tax Expense (Benefit) + References No definition available. + Details
Name: | msif_RealizedGainLossInvestmentAndDerivativeOperatingDeferredStateAndOtherTaxExpenseBenefit
Namespace Prefix: | msif_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Realized Gain (Loss), Investment And Derivative, Operating, Deferred Tax Expense (Benefit) + References No definition available. + Details
Name: | msif_RealizedGainLossInvestmentAndDerivativeOperatingDeferredTaxExpenseBenefit
Namespace Prefix: | msif_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Realized Gain (Loss), Investment And Derivative, Operating, Federal Tax Expense (Benefit), Current + References No definition available. + Details
Name: | msif_RealizedGainLossInvestmentAndDerivativeOperatingFederalTaxExpenseBenefitCurrent
Namespace Prefix: | msif_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Realized Gain (Loss), Investment And Derivative, Operating, Tax Expense (Benefit), Current + References No definition available. + Details
Name: | msif_RealizedGainLossInvestmentAndDerivativeOperatingTaxExpenseBenefitCurrent
Namespace Prefix: | msif_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_CurrentFederalStateAndLocalTaxExpenseBenefitAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of tax expense (benefit) on investment income classified as operating. Excludes realized and unrealized gain (loss) on investment. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.6-07(5)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 220 -Name Accounting Standards Codification -Section 45 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479105/946-220-45-4 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 220 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147478297/946-220-50-1 Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 946 -SubTopic 220 -Name Accounting Standards Codification -Section 45 -Paragraph 3 -Subparagraph (g) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479105/946-220-45-3 + Details
Name: | us-gaap_InvestmentIncomeOperatingTaxExpenseBenefit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of tax expense (benefit) from realized gain (loss) on investment and derivative, classified as operating. Investment includes, but is not limited to, debt and equity securities, security sold short, real estate, and commodity. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 946 -SubTopic 830 -Name Accounting Standards Codification -Section 45 -Paragraph 37 -Publisher FASB -URI https://asc.fasb.org/1943274/2147477346/946-830-45-37 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 946 -SubTopic 220 -Name Accounting Standards Codification -Section 45 -Paragraph 6 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479105/946-220-45-6 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 220 -Name Accounting Standards Codification -Section 45 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479105/946-220-45-4 Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 946 -SubTopic 220 -Name Accounting Standards Codification -Section 45 -Paragraph 3 -Subparagraph (g) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479105/946-220-45-3 + Details
Name: | us-gaap_RealizedGainLossInvestmentAndDerivativeOperatingTaxExpenseBenefit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration