Consolidated Statements of Assets and Liabilities (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2024		Dec. 31, 2023
Amortized cost	$ 6,420,607	[1],[2],[3],[4],[5]	$ 6,213,226	[6],[7],[8],[9],[10],[11]
Unamortized debt issuance costs	$ 29,267		$ 35,064
Common stock, par value (in usd per share)	$ 0.01		$ 0.01
Common stock, shares authorized (in shares)	500,000,000		500,000,000
Common stock, shares issued (in shares)	210,978,842		207,252,229
Common stock, shares outstanding (in shares)	210,978,842		207,252,229
Non-controlled, non-affiliated investments
Amortized cost	$ 5,947,435	[1],[3]	$ 5,841,371	[6],[8]
Non-controlled, affiliated investments
Amortized cost	395,721	[1],[3]	296,593	[6],[8]
Controlled, affiliated investments
Amortized cost	$ 77,451	[1],[3]	$ 75,262	[6],[8]

[1] As of September 30, 2024, the net estimated unrealized loss on investments for U.S. federal income tax purposes was $29.3 million based on a tax cost basis of $6.43 billion. As of September 30, 2024, the estimated aggregate gross unrealized loss for U.S. federal income tax purposes was $190.0 million and the estimated aggregate gross unrealized gain for U.S. federal income tax purposes was $160.7 million.

[2] Certain portfolio company investments are subject to contractual restrictions on sales. Refer to footnote 19 for additional information on our restricted securities.

[3] The amortized cost represents the original cost adjusted for the amortization or accretion of premium or discount, as applicable, on debt investments using the effective interest method.

[4] Unless otherwise indicated, all investments are non-controlled, non-affiliated investments. Non-controlled, non-affiliated investments are defined as investments in which the Company owns less than 5% of the portfolio company’s outstanding voting securities and does not have the power to exercise control over the management or policies of such portfolio company.

[5] Unless otherwise indicated, the Company’s portfolio companies are pledged as collateral supporting the amounts outstanding under the Revolving Credit Facility, SPV Asset Facility I, SPV Asset Facility II and CLO 2020-1. See Note 5 “Debt”.

[6] As of December 31, 2023, the net estimated unrealized loss on investments for U.S. federal income tax purposes was $25.4 million based on a tax cost basis of $6.2 billion. As of December 31, 2023, the estimated aggregate gross unrealized loss for U.S. federal income tax purposes was $160.4 million and the estimated aggregate gross unrealized gain for U.S. federal income tax purposes was $135.0 million.

[7] Certain portfolio company investments are subject to contractual restrictions on sales. Refer to footnote 19 for additional information on our restricted securities.

[8] The amortized cost represents the original cost adjusted for the amortization or accretion of premium or discount, as applicable, on debt investments using the effective interest method.

[9] Unless otherwise indicated, all investments are considered Level 3 investments.

[10] Unless otherwise indicated, all investments are non-controlled, non-affiliated investments. Non-controlled, non-affiliated investments are defined as investments in which the Company owns less than 5% of the portfolio company’s outstanding voting securities and does not have the power to exercise control over the management or policies of such portfolio company.

[11] Unless otherwise indicated, the Company’s portfolio companies are pledged as collateral supporting the amounts outstanding under the Revolving Credit Facility, SPV Asset Facility I, SPV Asset Facility II and CLO 2020-1. See Note 5 “Debt”.