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N-2 - USD ($) $ / shares in Units, $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Cover [Abstract] |  |  |  |  |  |
Entity Central Index Key | 0001736035 |  |  |  |  |
Amendment Flag | false |  |  |  |  |
Securities Act File Number | 814-01299 |  |  |  |  |
Document Type | 10-Q |  |  |  |  |
Entity Registrant Name | Blackstone Secured Lending Fund |  |  |  |  |
Entity Address, Address Line One | 345 Park Avenue |  |  |  |  |
Entity Address, Address Line Two | 31st Floor |  |  |  |  |
Entity Address, City or Town | New York |  |  |  |  |
Entity Address, State or Province | NY |  |  |  |  |
Entity Address, Postal Zip Code | 10154 |  |  |  |  |
City Area Code | 212 |  |  |  |  |
Local Phone Number | 503-2100 |  |  |  |  |
Entity Emerging Growth Company | false |  |  |  |  |
Financial Highlights [Abstract] |  |  |  |  |  |
Senior Securities [Table Text Block] | The following is information about the Company’s senior securities as of the dates indicated in the below table:
Class and Period | Total Amount Outstanding Exclusive of Treasury Securities(1) ($ in millions) |  | Asset Coverage per Unit (2) ($ in millions) |  | Involuntary Liquidating Preference per Unit(3) |  | Average Market Value per Unit(4)
Subscription Facility (5) |  |  |  |  |  |  |
March 31, 2023 | $ | — |  |  | $ | — |  |  | — |  | N/A
December 31, 2022 | — |  |  | — |  |  | — |  | N/A
December 31, 2021 | — |  |  | — |  |  | — |  | N/A
December 31, 2020 | — |  |  | — |  |  | — |  | N/A
December 31, 2019 | 119.8 |  |  | 2,151.0 |  |  | — |  | N/A
December 31, 2018 | — |  |  | — |  |  | — |  | N/A
Jackson Hole Funding Facility |  |  |  |  |  |  |
March 31, 2023 | 360.0 |  |  | 1,764.0 |  | — |  | N/A
December 31, 2022 | 360.0 |  |  | 1,748.0 |  | — |  | N/A
December 31, 2021 | 361.0 |  |  | 1,802.0 |  | — |  | N/A
December 31, 2020 | 362.3 |  |  | 2,300.0 |  | — |  | N/A
December 31, 2019 | 514.2 |  |  | 2,151.0 |  | — |  | N/A
December 31, 2018 | 120.0 |  |  | 2,278.0 |  | — |  | N/A
Breckenridge Funding Facility |  |  |  |  |  |  |
March 31, 2023 | 809.5 |  |  | 1,764.0 |  | — |  | N/A
December 31, 2022 | 825.0 |  |  | 1,748.0 |  | — |  | N/A
December 31, 2021 | 568.7 |  |  | 1,802.0 |  | — |  | N/A
December 31, 2020 | 569.0 |  |  | 2,300.0 |  | — |  | N/A
December 31, 2019 | 820.3 |  |  | 2,151.0 |  | — |  | N/A
December 31, 2018 | 65.0 |  |  | 2,278.0 |  | — |  | N/A
Big Sky Funding facility |  |  |  |  |  |  |
March 31, 2023 | 499.6 |  |  | 1,764.0 |  | — |  | N/A
December 31, 2022 | 499.6 |  |  | 1,748.0 |  | — |  | N/A
December 31, 2021 | 499.6 |  |  | 1,802.0 |  | — |  | N/A
December 31, 2020 | 200.3 |  |  | 2,300.0 |  | — |  | N/A
December 31, 2019 | — |  |  | — |  |  | — |  | N/A
December 31, 2018 | — |  |  | — |  |  | — |  | N/A
Revolving Credit Facility |  |  |  |  |  |  |
March 31, 2023 | 615.5 |  |  | 1,764.0 |  | — |  | N/A
December 31, 2022 | 678.4 |  |  | 1,748.0 |  | — |  | N/A
December 31, 2021 | 915.0 |  |  | 1,802.0 |  | — |  | N/A
December 31, 2020 | 182.9 |  |  | 2,300.0 |  | — |  | N/A
December 31, 2019 | — |  |  | — |  |  | — |  | N/A
December 31, 2018 | — |  |  | — |  |  | — |  | N/A
2023 Notes |  |  |  |  |  |  |
March 31, 2023 | 400.0 |  |  | 1,764.0 |  | — |  | N/A
December 31, 2022 | 400.0 |  |  | 1,748.0 |  | — |  | N/A
December 31, 2021 | 400.0 |  |  | 1,802.0 |  | — |  | N/A
December 31, 2020 | 400.0 |  |  | 2,300.0 |  | — |  | N/A
December 31, 2019 | — |  |  | — |  |  | — |  | N/A
December 31, 2018 | — |  |  | — |  |  | — |  | N/A
2026 Notes |  |  |  |  |  |  |
March 31, 2023 | 800.0 |  |  | 1,764.0 |  | — |  | N/A
December 31, 2022 | 800.0 |  |  | 1,748.0 |  | — |  | N/A
December 31, 2021 | 800.0 |  |  | 1,802.0 |  | — |  | N/A
December 31, 2020 | 800.0 |  |  | 2,300.0 |  | — |  | N/A
December 31, 2019 | — |  |  | — |  |  | — |  | N/A
December 31, 2018 | — |  |  | — |  |  | — |  | N/A
New 2026 Notes |  |  |  |  |  |  |
March 31, 2023 | 700.0 |  |  | 1,764.0 |  | — |  | N/A
December 31, 2022 | 700.0 |  |  | 1,748.0 |  | — |  | N/A
December 31, 2021 | 700.0 |  |  | 1,802.0 |  | — |  | N/A
December 31, 2020 | — |  |  | — |  |  | — |  | N/A
December 31, 2019 | — |  |  | — |  |  | — |  | N/A
December 31, 2018 | — |  |  | — |  |  | — |  | N/A
2027 Notes |  |  |  |  |  |  |
March 31, 2023 | 650.0 |  |  | 1,764.0 |  | — |  | N/A
December 31, 2022 | 650.0 |  |  | 1,748.0 |  | — |  | N/A
December 31, 2021 | 650.0 |  |  | 1,802.0 |  | — |  | N/A
December 31, 2020 | — |  |  | — |  |  | — |  | N/A
December 31, 2019 | — |  |  | — |  |  | — |  | N/A
December 31, 2018 | — |  |  | — |  |  | — |  | N/A
2028 Notes |  |  |  |  |  |  |
March 31, 2023 | 650.0 |  |  | 1,764.0 |  | — |  | N/A
December 31, 2022 | 650.0 |  |  | 1,748.0 |  | — |  | N/A
December 31, 2021 | 650.0 |  |  | 1,802.0 |  | — |  | N/A
December 31, 2020 | — |  |  | — |  |  | — |  | N/A
December 31, 2019 | — |  |  | — |  |  | — |  | N/A
December 31, 2018 | — |  |  | — |  |  | — |  | N/A
(1)Total amount of each class of senior securities outstanding at the end of the period presented. (2)Asset coverage per unit is the ratio of the carrying value of our total assets, less all liabilities excluding indebtedness represented by senior securities in this table, to the aggregate amount of senior securities representing indebtedness. Asset coverage per unit is expressed in terms of dollar amounts per $1,000 of indebtedness and is calculated on a consolidated basis. (3)The amount to which such class of senior security would be entitled upon our involuntary liquidation in preference to any security junior to it. The “-” in this column indicates information that the SEC expressly does not require to be disclosed for certain types of senior securities. (4)Not applicable because the senior securities are not registered for public trading. (5)The Subscription Facility was terminated on November 3, 2020. |  |  |  |  |
General Description of Registrant [Abstract] |  |  |  |  |  |
Investment Objectives and Practices [Text Block] | Blackstone Secured Lending Fund (together with its consolidated subsidiaries, the “Company”), is a Delaware statutory trust formed on March 26, 2018, and structured as an externally managed, non-diversified closed-end management investment company. On October 26, 2018, the Company elected to be regulated as a business development company (“BDC”) under the Investment Company Act of 1940, as amended (together with the rules and regulations promulgated thereunder, the “1940 Act”). In addition, the Company elected to be treated for U.S. federal income tax purposes, and intends to qualify annually, as a regulated investment company (a “RIC”), under Subchapter M of the Internal Revenue Code of 1986, as amended (together with the rules and regulations promulgated thereunder, the “Code”). The Company is externally managed by Blackstone Credit BDC Advisors LLC (the “Adviser”) an affiliate of Blackstone Alternative Credit Advisors LP (the “Administrator” and, collectively with its affiliates in the credit-focused business of Blackstone Inc. (“Blackstone”), “Blackstone Credit,” which, for the avoidance of doubt, excludes Harvest Fund Advisors LLC and Blackstone Insurance Solutions). The Administrator provides certain administrative and other services necessary for the Company to operate pursuant to an administration agreement (the “Administration Agreement”). Blackstone Credit is part of the credit-focused platform of Blackstone and is the primary part of its Credit & Insurance reporting segment. The Company’s investment objectives are to generate current income and, to a lesser extent, long-term capital appreciation. The Company seeks to achieve its investment objectives primarily through originated loans and other securities, including syndicated loans, of private U.S. companies, typically in the form of first lien senior secured and unitranche loans (including first-out/last-out loans), and to a lesser extent, second lien, third lien, unsecured and subordinated loans and other debt and equity securities. Our investment objectives are to generate current income and, to a lesser extent, long-term capital appreciation. Under normal market conditions, we generally invest at least 80% of our total assets (net assets plus borrowings for investment purposes) in secured debt investments and our portfolio is composed primarily of first lien senior secured and unitranche loans. To a lesser extent, we have and may continue to also invest in second lien, third lien, unsecured or subordinated loans and other debt and equity securities. In limited instances we may retain the “last out” portion of a first-lien loan. In such cases, the “first out” portion of the first lien loan would receive priority with respect to payment over our “last out” position. In exchange for the higher risk of loss associated with such “last out” portion, we would earn a higher rate of interest than the “first out” position." We do not currently focus on investments in issuers that are distressed or in need of rescue financing. Financial Condition, Liquidity and Capital Resources Our liquidity and capital resources are generated primarily from cash flows from interest, dividends and fees earned from our investments and principal repayments, our credit facilities, debt securitization transactions, and other secured and unsecured debt. We may also generate cash flow from operations, future borrowings and future offerings of securities including public and/or private issuances of debt and/or equity securities through both registered offerings and private offerings. The primary uses of our cash and cash equivalents are for (i) originating loans and purchasing senior secured debt investments, (ii) funding the costs of our operations (including fees paid to our Adviser and expense reimbursements paid to our Administrator), (iii) debt service, repayment and other financing costs of our borrowings and (iv) cash distributions to the holders of our shares. As of both March 31, 2023 and December 31, 2022, we had 4 revolving credit facilities outstanding and we had 5 unsecured bonds outstanding. We may from time to time enter into additional credit facilities, increase the size of our existing credit facilities or issue further debt securities. Any such incurrence or issuance would be subject to prevailing market conditions, our liquidity requirements, contractual and regulatory restrictions and other factors. In accordance with the 1940 Act, with certain limited exceptions, we are only allowed to incur borrowings, issue debt securities or issue preferred stock, if immediately after the borrowing or issuance, the ratio of total assets (less total liabilities other than indebtedness) to total indebtedness plus preferred stock, is at least 150%. As of March 31, 2023 and December 31, 2022, we had an aggregate amount of $5,484.6 million and $5,563.0 million of senior securities outstanding and our asset coverage ratio was 176.4% and 174.8%, respectively. We seek to carefully consider our unfunded commitments for the purpose of planning our ongoing financial leverage. Further, we maintain sufficient borrowing capacity within the 150% asset coverage limitation to cover any outstanding unfunded commitments we are required to fund. Cash and cash equivalents as of March 31, 2023, taken together with our $1,065.4 million of available capacity under our credit facilities (subject to borrowing base availability) is expected to be sufficient for our investing activities and to conduct our operations in the near term. Additionally, we held $199.7 million of Level 2 debt investments as of March 31, 2023, which could provide additional liquidity if necessary. Although we have historically been able to obtain sufficient borrowing capacity, a deterioration in economic conditions or any other negative economic developments could restrict our access to financing in the future. We may not be able to find new financing for future investments or liquidity needs and, even if we are able to obtain such financing, such financing may not be on as favorable terms as we have previously obtained. These factors may limit our ability to make new investments and adversely impact our results of operations.As of March 31, 2023, we had $103.0 million in cash and cash equivalents. During the three months ended March 31, 2023, cash provided by operating activities was $155.9 million, primarily as a result of proceeds from sale of investments and principal repayment of $109.1 million partially offset by purchase of investments of $102.3 million. Cash used in financing activities was $186.8 million during the period, which was primarily as a result of net repayments on our credit facilities of $92.7 million and dividends paid in cash of $91.8 million |  |  |  |  |
Risk Factors [Table Text Block] | Financial Condition, Liquidity and Capital Resources Our liquidity and capital resources are generated primarily from cash flows from interest, dividends and fees earned from our investments and principal repayments, our credit facilities, debt securitization transactions, and other secured and unsecured debt. We may also generate cash flow from operations, future borrowings and future offerings of securities including public and/or private issuances of debt and/or equity securities through both registered offerings and private offerings. The primary uses of our cash and cash equivalents are for (i) originating loans and purchasing senior secured debt investments, (ii) funding the costs of our operations (including fees paid to our Adviser and expense reimbursements paid to our Administrator), (iii) debt service, repayment and other financing costs of our borrowings and (iv) cash distributions to the holders of our shares. As of both March 31, 2023 and December 31, 2022, we had 4 revolving credit facilities outstanding and we had 5 unsecured bonds outstanding. We may from time to time enter into additional credit facilities, increase the size of our existing credit facilities or issue further debt securities. Any such incurrence or issuance would be subject to prevailing market conditions, our liquidity requirements, contractual and regulatory restrictions and other factors. In accordance with the 1940 Act, with certain limited exceptions, we are only allowed to incur borrowings, issue debt securities or issue preferred stock, if immediately after the borrowing or issuance, the ratio of total assets (less total liabilities other than indebtedness) to total indebtedness plus preferred stock, is at least 150%. As of March 31, 2023 and December 31, 2022, we had an aggregate amount of $5,484.6 million and $5,563.0 million of senior securities outstanding and our asset coverage ratio was 176.4% and 174.8%, respectively. We seek to carefully consider our unfunded commitments for the purpose of planning our ongoing financial leverage. Further, we maintain sufficient borrowing capacity within the 150% asset coverage limitation to cover any outstanding unfunded commitments we are required to fund. Cash and cash equivalents as of March 31, 2023, taken together with our $1,065.4 million of available capacity under our credit facilities (subject to borrowing base availability) is expected to be sufficient for our investing activities and to conduct our operations in the near term. Additionally, we held $199.7 million of Level 2 debt investments as of March 31, 2023, which could provide additional liquidity if necessary. Although we have historically been able to obtain sufficient borrowing capacity, a deterioration in economic conditions or any other negative economic developments could restrict our access to financing in the future. We may not be able to find new financing for future investments or liquidity needs and, even if we are able to obtain such financing, such financing may not be on as favorable terms as we have previously obtained. These factors may limit our ability to make new investments and adversely impact our results of operations.As of March 31, 2023, we had $103.0 million in cash and cash equivalents. During the three months ended March 31, 2023, cash provided by operating activities was $155.9 million, primarily as a result of proceeds from sale of investments and principal repayment of $109.1 million partially offset by purchase of investments of $102.3 million. Cash used in financing activities was $186.8 million during the period, which was primarily as a result of net repayments on our credit facilities of $92.7 million and dividends paid in cash of $91.8 million Item 3. Quantitative and Qualitative Disclosures About Market Risk. Uncertainty with respect to the economic conditions has introduced significant volatility in the financial markets, and the effect of the volatility could materially impact our market risks. We are subject to financial market risks, including valuation risk, interest rate risk and inflation risk. Our exposure to market risk has not materially changed from what was previously disclosed in our Annual Report on Form 10-K for the fiscal year ended December 31, 2022. |  |  |  |  |
Effects of Leverage [Text Block] | Financial Condition, Liquidity and Capital Resources Our liquidity and capital resources are generated primarily from cash flows from interest, dividends and fees earned from our investments and principal repayments, our credit facilities, debt securitization transactions, and other secured and unsecured debt. We may also generate cash flow from operations, future borrowings and future offerings of securities including public and/or private issuances of debt and/or equity securities through both registered offerings and private offerings. The primary uses of our cash and cash equivalents are for (i) originating loans and purchasing senior secured debt investments, (ii) funding the costs of our operations (including fees paid to our Adviser and expense reimbursements paid to our Administrator), (iii) debt service, repayment and other financing costs of our borrowings and (iv) cash distributions to the holders of our shares. As of both March 31, 2023 and December 31, 2022, we had 4 revolving credit facilities outstanding and we had 5 unsecured bonds outstanding. We may from time to time enter into additional credit facilities, increase the size of our existing credit facilities or issue further debt securities. Any such incurrence or issuance would be subject to prevailing market conditions, our liquidity requirements, contractual and regulatory restrictions and other factors. In accordance with the 1940 Act, with certain limited exceptions, we are only allowed to incur borrowings, issue debt securities or issue preferred stock, if immediately after the borrowing or issuance, the ratio of total assets (less total liabilities other than indebtedness) to total indebtedness plus preferred stock, is at least 150%. As of March 31, 2023 and December 31, 2022, we had an aggregate amount of $5,484.6 million and $5,563.0 million of senior securities outstanding and our asset coverage ratio was 176.4% and 174.8%, respectively. We seek to carefully consider our unfunded commitments for the purpose of planning our ongoing financial leverage. Further, we maintain sufficient borrowing capacity within the 150% asset coverage limitation to cover any outstanding unfunded commitments we are required to fund. Cash and cash equivalents as of March 31, 2023, taken together with our $1,065.4 million of available capacity under our credit facilities (subject to borrowing base availability) is expected to be sufficient for our investing activities and to conduct our operations in the near term. Additionally, we held $199.7 million of Level 2 debt investments as of March 31, 2023, which could provide additional liquidity if necessary. Although we have historically been able to obtain sufficient borrowing capacity, a deterioration in economic conditions or any other negative economic developments could restrict our access to financing in the future. We may not be able to find new financing for future investments or liquidity needs and, even if we are able to obtain such financing, such financing may not be on as favorable terms as we have previously obtained. These factors may limit our ability to make new investments and adversely impact our results of operations.As of March 31, 2023, we had $103.0 million in cash and cash equivalents. During the three months ended March 31, 2023, cash provided by operating activities was $155.9 million, primarily as a result of proceeds from sale of investments and principal repayment of $109.1 million partially offset by purchase of investments of $102.3 million. Cash used in financing activities was $186.8 million during the period, which was primarily as a result of net repayments on our credit facilities of $92.7 million and dividends paid in cash of $91.8 million |  |  |  |  |
Share Price [Table Text Block] | Financial Condition, Liquidity and Capital Resources Our liquidity and capital resources are generated primarily from cash flows from interest, dividends and fees earned from our investments and principal repayments, our credit facilities, debt securitization transactions, and other secured and unsecured debt. We may also generate cash flow from operations, future borrowings and future offerings of securities including public and/or private issuances of debt and/or equity securities through both registered offerings and private offerings. The primary uses of our cash and cash equivalents are for (i) originating loans and purchasing senior secured debt investments, (ii) funding the costs of our operations (including fees paid to our Adviser and expense reimbursements paid to our Administrator), (iii) debt service, repayment and other financing costs of our borrowings and (iv) cash distributions to the holders of our shares. As of both March 31, 2023 and December 31, 2022, we had 4 revolving credit facilities outstanding and we had 5 unsecured bonds outstanding. We may from time to time enter into additional credit facilities, increase the size of our existing credit facilities or issue further debt securities. Any such incurrence or issuance would be subject to prevailing market conditions, our liquidity requirements, contractual and regulatory restrictions and other factors. In accordance with the 1940 Act, with certain limited exceptions, we are only allowed to incur borrowings, issue debt securities or issue preferred stock, if immediately after the borrowing or issuance, the ratio of total assets (less total liabilities other than indebtedness) to total indebtedness plus preferred stock, is at least 150%. As of March 31, 2023 and December 31, 2022, we had an aggregate amount of $5,484.6 million and $5,563.0 million of senior securities outstanding and our asset coverage ratio was 176.4% and 174.8%, respectively. We seek to carefully consider our unfunded commitments for the purpose of planning our ongoing financial leverage. Further, we maintain sufficient borrowing capacity within the 150% asset coverage limitation to cover any outstanding unfunded commitments we are required to fund. Cash and cash equivalents as of March 31, 2023, taken together with our $1,065.4 million of available capacity under our credit facilities (subject to borrowing base availability) is expected to be sufficient for our investing activities and to conduct our operations in the near term. Additionally, we held $199.7 million of Level 2 debt investments as of March 31, 2023, which could provide additional liquidity if necessary. Although we have historically been able to obtain sufficient borrowing capacity, a deterioration in economic conditions or any other negative economic developments could restrict our access to financing in the future. We may not be able to find new financing for future investments or liquidity needs and, even if we are able to obtain such financing, such financing may not be on as favorable terms as we have previously obtained. These factors may limit our ability to make new investments and adversely impact our results of operations.As of March 31, 2023, we had $103.0 million in cash and cash equivalents. During the three months ended March 31, 2023, cash provided by operating activities was $155.9 million, primarily as a result of proceeds from sale of investments and principal repayment of $109.1 million partially offset by purchase of investments of $102.3 million. Cash used in financing activities was $186.8 million during the period, which was primarily as a result of net repayments on our credit facilities of $92.7 million and dividends paid in cash of $91.8 million |  |  |  |  |
Subscription Facility [Member] |  |  |  |  |  |
Financial Highlights [Abstract] |  |  |  |  |  |
Senior Securities Amount | $ 0.0 | $ 0.0 | $ 0.0 | $ 0.0 | $ 119.8 | $ 0.0
Senior Securities Coverage per Unit | $ 0 | $ 0 | $ 0 | $ 0 | $ 2,151 | $ 0
Senior Securities Involuntary Liquidating Preference per Unit | $ 0 | $ 0 | $ 0 | $ 0 | $ 0 | $ 0

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- Definition A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Exchange Act -Number 240 -Section 12 -Subsection b-2 + Details
Name: | dei_EntityCentralIndexKey
Namespace Prefix: | dei_
Data Type: | dei:centralIndexKeyItemType
Balance Type: | na
Period Type: | duration

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- Definition Indicate if registrant meets the emerging growth company criteria. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Exchange Act -Number 240 -Section 12 -Subsection b-2 + Details
Name: | dei_EntityEmergingGrowthCompany
Namespace Prefix: | dei_
Data Type: | xbrli:booleanItemType
Balance Type: | na
Period Type: | duration

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- Definition Commission file number. The field allows up to 17 characters. The prefix may contain 1-3 digits, the sequence number may contain 1-8 digits, the optional suffix may contain 1-4 characters, and the fields are separated with a hyphen. + References No definition available. + Details
Name: | dei_EntityFileNumber
Namespace Prefix: | dei_
Data Type: | dei:fileNumberItemType
Balance Type: | na
Period Type: | duration

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- Definition The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Exchange Act -Number 240 -Section 12 -Subsection b-2 + Details
Name: | dei_EntityRegistrantName
Namespace Prefix: | dei_
Data Type: | xbrli:normalizedStringItemType
Balance Type: | na
Period Type: | duration

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- Definition Local phone number for entity. + References No definition available. + Details
Name: | dei_LocalPhoneNumber
Namespace Prefix: | dei_
Data Type: | xbrli:normalizedStringItemType
Balance Type: | na
Period Type: | duration

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- Details
Name: | cef_SecurityAxis=bxsl_SubscriptionFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |