Financial Highlights - Schedule Of Financial Highlights (Details) $ / shares in Units, $ in Millions		3 Months Ended								12 Months Ended
	Jun. 15, 2020	Dec. 31, 2024 USD ($) $ / shares shares	Sep. 30, 2024 $ / shares	Jun. 30, 2024 $ / shares	Mar. 31, 2024 $ / shares	Dec. 31, 2023 USD ($) $ / shares shares	Sep. 30, 2023 $ / shares	Jun. 30, 2023 $ / shares	Mar. 31, 2023 $ / shares	Dec. 31, 2024 USD ($) $ / shares shares	Dec. 31, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares	Nov. 20, 2024	Nov. 21, 2023	Jun. 16, 2021
Investment Company, Financial Highlights [Roll Forward]
Net asset value, beginning of year (in dollars per share)					$ 24.46				$ 24.89	$ 24.46	$ 24.89	$ 27.17	$ 25.02	$ 30.54
Results of operations
Net investment income (loss) (in dollars per share)		$ 0.61	$ 0.77	$ 0.77	$ 0.76	$ 0.71	$ 0.84	$ 0.82	$ 0.81	2.90	3.18	3.05	2.76	2.66
Net realized gain (loss) and unrealized appreciation (depreciation) (in dollars per share)										(0.82)	(0.70)	(2.74)	4.28	(5.85)
Net increase (decrease) in net assets resulting from operations (in dollars per share)										2.08	2.48	0.31	7.04	(3.19)
Stockholder distributions
Distributions from net investment income (in dollars per share)										(2.90)	(2.95)	(2.66)	(2.47)	(2.56)
Distributions from net realized gain on investments (in dollars per share)										0	0	0	0	0
Net decrease in net assets resulting from stockholder distributions (in dollars per share)										(2.90)	(2.95)	(2.66)	(2.47)	(2.56)
Capital share transactions
Issuance of common stock (in dollars per share)										0	0	0	(2.20)	0
Repurchases of common stock (in dollars per share)										0	0.04	0.07	0.01	0.23
Deduction of deferred costs (in dollars per share)										0	0	0	(0.23)	0
Net increase (decrease) in net assets resulting from capital share transactions (in dollars per share)										0	0.04	0.07	(2.42)	0.23
Net asset value, end of year (in dollars per share)		23.64				24.46				23.64	24.46	24.89	27.17	25.02
Per share market value, end of year (in dollars per share)		$ 21.72				$ 19.97				$ 21.72	$ 19.97	$ 17.50	$ 20.94	$ 16.56
Shares outstanding, end of year (in shares) | shares		280,066,433				280,066,433				280,066,433	280,066,433	281,731,750	284,543,091	123,755,965
Total return based on net asset value										8.50%	10.12%	1.40%	18.47%	(9.69%)
Total return based on market value										25.29%	32.45%	(4.61%)	41.45%	(19.73%)
Ratio/Supplemental Data:
Net assets, end of year | $		$ 6,622				$ 6,849				$ 6,622	$ 6,849	$ 7,012	$ 7,730	$ 3,096
Ratio of net investment income to average net assets										11.90%	12.67%	11.42%	10.36%	10.44%
Ratio of total operating expenses to average net assets										13.29%	13.32%	10.96%	9.35%	9.71%
Ratio of net operating expenses to average net assets										13.29%	13.32%	10.17%	8.82%	9.71%
Portfolio turnover										33.38%	12.14%	28.61%	49.82%	32.95%
Total amount of senior securities outstanding, exclusive of treasury securities | $		$ 7,385				$ 8,223				$ 7,385	$ 8,223	$ 8,731	$ 9,179	$ 4,042
Asset coverage per ratio (as percent)		190.00%				183.00%				190.00%	183.00%	180.00%	184.00%	177.00%
Stock split conversion ratio	0.25
4.250% Unsecured Notes due 2025 | Unsecured Notes
Ratio/Supplemental Data:
Total amount of senior securities outstanding, exclusive of treasury securities | $		$ 475				$ 475				$ 475	$ 475
Stated interest rate (as percent)		4.25%				4.25%				4.25%	4.25%		4.25%		4.25%	4.25%	4.25%