Consolidated Statements of Assets and Liabilities (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Statement Of Financial Position [Abstract]
Non-controlled/non-affiliated investments at cost	$ 3,664,754	$ 3,416,195
Non-controlled affiliated investments at cost	58,267	58,221
Controlled affiliated investments at cost	34,745	33,374
Investments at cost	3,757,766	3,507,790
Debt issuance costs	$ 9,571	$ 12,296
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	102,778,441	101,818,811
Common stock, shares outstanding	102,778,441	101,818,811