{"cik":"0001562818","entityName":"BlackRock Multi-Sector Income Trust","facts":{"cef":{"DividendReinvestmentAndCashPurchaseFees":{"label":"","description":"","units":{"USD":[{"end":"2026-04-01","val":2.5,"accn":"0001193125-26-147762","fy":null,"fp":null,"form":"424B5","filed":"2026-04-08","frame":"CY2026Q1I"}]}},"ExpenseExampleYear01":{"label":"","description":"","units":{"USD":[{"end":"2026-04-01","val":43,"accn":"0001193125-26-147762","fy":null,"fp":null,"form":"424B5","filed":"2026-04-08","frame":"CY2026Q1I"}]}},"ExpenseExampleYears1to10":{"label":"","description":"","units":{"USD":[{"end":"2026-04-01","val":362,"accn":"0001193125-26-147762","fy":null,"fp":null,"form":"424B5","filed":"2026-04-08","frame":"CY2026Q1I"}]}},"ExpenseExampleYears1to3":{"label":"","description":"","units":{"USD":[{"end":"2026-04-01","val":110,"accn":"0001193125-26-147762","fy":null,"fp":null,"form":"424B5","filed":"2026-04-08","frame":"CY2026Q1I"}]}},"ExpenseExampleYears1to5":{"label":"","description":"","units":{"USD":[{"end":"2026-04-01","val":179,"accn":"0001193125-26-147762","fy":null,"fp":null,"form":"424B5","filed":"2026-04-08","frame":"CY2026Q1I"}]}},"ManagementFeesPercent":{"label":"","description":"","units":{"pure":[{"end":"2026-04-01","val":0.0117,"accn":"0001193125-26-147762","fy":null,"fp":null,"form":"424B5","filed":"2026-04-08","frame":"CY2026Q1I"}]}},"NetExpenseOverAssetsPercent":{"label":"","description":"","units":{"pure":[{"end":"2026-04-01","val":0.0326,"accn":"0001193125-26-147762","fy":null,"fp":null,"form":"424B5","filed":"2026-04-08","frame":"CY2026Q1I"}]}},"OtherAnnualExpense1Percent":{"label":"","description":"","units":{"pure":[{"end":"2026-04-01","val":0.0009,"accn":"0001193125-26-147762","fy":null,"fp":null,"form":"424B5","filed":"2026-04-08","frame":"CY2026Q1I"}]}},"OtherAnnualExpense2Percent":{"label":"","description":"","units":{"pure":[{"end":"2026-04-01","val":0.02,"accn":"0001193125-26-147762","fy":null,"fp":null,"form":"424B5","filed":"2026-04-08","frame":"CY2026Q1I"}]}},"OtherAnnualExpensesPercent":{"label":"","description":"","units":{"pure":[{"end":"2026-04-01","val":0.0209,"accn":"0001193125-26-147762","fy":null,"fp":null,"form":"424B5","filed":"2026-04-08","frame":"CY2026Q1I"}]}},"OtherTransactionExpensesPercent":{"label":"","description":"","units":{"pure":[{"end":"2026-04-01","val":0.0002,"accn":"0001193125-26-147762","fy":null,"fp":null,"form":"424B5","filed":"2026-04-08","frame":"CY2026Q1I"}]}},"SalesLoadPercent":{"label":"","description":"","units":{"pure":[{"end":"2026-04-01","val":0.01,"accn":"0001193125-26-147762","fy":null,"fp":null,"form":"424B5","filed":"2026-04-08","frame":"CY2026Q1I"}]}},"TotalAnnualExpensesPercent":{"label":"","description":"","units":{"pure":[{"end":"2026-04-01","val":0.0326,"accn":"0001193125-26-147762","fy":null,"fp":null,"form":"424B5","filed":"2026-04-08","frame":"CY2026Q1I"}]}},"WaiversAndReimbursementsOfFeesPercent":{"label":"","description":"","units":{"pure":[{"end":"2026-04-01","val":0,"accn":"0001193125-26-147762","fy":null,"fp":null,"form":"424B5","filed":"2026-04-08","frame":"CY2026Q1I"}]}},"HighestPriceOrBid":{"label":"","description":"","units":{"USD/shares":[{"start":"2026-01-01","end":"2026-06-30","val":13.4,"accn":"0001193125-26-381584","fy":null,"fp":null,"form":"N-CSRS","filed":"2026-09-03"}]}},"HighestPriceOrBidNav":{"label":"","description":"","units":{"USD/shares":[{"start":"2026-01-01","end":"2026-06-30","val":13.98,"accn":"0001193125-26-381584","fy":null,"fp":null,"form":"N-CSRS","filed":"2026-09-03"}]}},"HighestPriceOrBidPremiumDiscountToNavPercent":{"label":"","description":"","units":{"pure":[{"start":"2026-01-01","end":"2026-06-30","val":-0.0413,"accn":"0001193125-26-381584","fy":null,"fp":null,"form":"N-CSRS","filed":"2026-09-03"}]}},"LowestPriceOrBid":{"label":"","description":"","units":{"USD/shares":[{"start":"2026-01-01","end":"2026-06-30","val":12.21,"accn":"0001193125-26-381584","fy":null,"fp":null,"form":"N-CSRS","filed":"2026-09-03"}]}},"LowestPriceOrBidNav":{"label":"","description":"","units":{"USD/shares":[{"start":"2026-01-01","end":"2026-06-30","val":13.26,"accn":"0001193125-26-381584","fy":null,"fp":null,"form":"N-CSRS","filed":"2026-09-03"}]}},"LowestPriceOrBidPremiumDiscountToNavPercent":{"label":"","description":"","units":{"pure":[{"start":"2026-01-01","end":"2026-06-30","val":-0.0439,"accn":"0001193125-26-381584","fy":null,"fp":null,"form":"N-CSRS","filed":"2026-09-03"}]}}},"us-gaap":{"NetAssetValuePerShare":{"label":"Net Asset Value Per Share","description":"Net asset value per share or per unit of investments in certain entities that calculate net asset value per share. Includes, but is not limited to, by unit, membership interest, or other ownership interest. Investment includes, but is not limited to, investment in certain hedge funds, venture capital funds, private equity funds, real estate partnerships or funds. Excludes fair value disclosure.","units":{"USD/shares":[{"end":"2025-12-31","val":13.91,"accn":"0001193125-26-381584","fy":null,"fp":null,"form":"N-CSRS","filed":"2026-09-03","frame":"CY2025Q4I"},{"end":"2026-06-30","val":13.3,"accn":"0001193125-26-381584","fy":null,"fp":null,"form":"N-CSRS","filed":"2026-09-03","frame":"CY2026Q2I"}]}},"SharePrice":{"label":"Share Price","description":"Price of a single share of a number of saleable stocks of a company.","units":{"USD/shares":[{"end":"2025-12-31","val":13.06,"accn":"0001193125-26-381584","fy":null,"fp":null,"form":"N-CSRS","filed":"2026-09-03","frame":"CY2025Q4I"},{"end":"2026-06-30","val":12.52,"accn":"0001193125-26-381584","fy":null,"fp":null,"form":"N-CSRS","filed":"2026-09-03","frame":"CY2026Q2I"}]}}}}}