Financial Highlights (Details) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended										6 Months Ended
	Jun. 09, 2022	Oct. 30, 2020	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Dec. 31, 2023	Dec. 31, 2022
Investment Company, Financial Highlights [Roll Forward]
Net asset value, beginning balance (in dollars per share)			$ 9.25	$ 9.24	$ 9.48	$ 9.94	$ 10.01	$ 10.48	$ 10.81	$ 10.60	$ 10.12		$ 9.24	$ 10.48
Net investment income (in dollars per share)			0.24	0.31	0.28	0.26	0.27	0.25	0.23	0.22	0.22	$ 0.21	0.54	0.52
Net realized and change in unrealized (losses) gains (in dollars per share)			(0.30)				(0.09)						(0.33)	(0.57)
Net increase from operations (in dollars per share)			(0.06)				0.18						0.21	(0.05)
Net increase (decrease) from operations applicable to common stockholders (in dollars per share)			(0.13)				0.14						0.10	(0.13)
Common stock transactions (in dollars per share)			(0.02)				(0.03)						(0.06)	(0.06)
Net asset value, ending balance (in dollars per share)			8.92	$ 9.25	$ 9.24	$ 9.48	9.94	$ 10.01	$ 10.48	$ 10.81	$ 10.60	$ 10.12	8.92	9.94
Per share market value (in dollars per share)			$ 5.99				$ 6.99						$ 5.99	$ 6.99
Total return based on market value			2.23%				15.74%						2.80%	5.26%
Total return based on net asset value			(0.43%)				1.94%						2.72%	(0.17%)
Shares outstanding at end of period (in shares)			412,794,121		404,033,549		398,852,478						412,794,121	398,852,478
Average weighted shares outstanding for the period (in shares)			410,942,812				397,685,022						408,646,716	396,011,231
Ratios/Supplemental Data
Net assets at end of year			$ 3,683,649	$ 3,780,866	$ 3,732,665		$ 3,966,391	$ 3,964,422	$ 4,119,123				$ 3,683,649	$ 3,966,391
Portfolio turnover rate			1.71%				1.00%						2.92%	2.97%
Ratio of operating expenses to average net assets applicable to common shares			12.22%				10.71%						12.04%	10.44%
Ratio of net investment income to average net assets applicable to common shares			10.39%				10.76%						11.92%	10.26%
5.50% Preferred Stock
Ratios/Supplemental Data
Dividend rate	5.50%	5.50%	5.50%				5.50%						5.50%	5.50%
6.50% Preferred Stock
Ratios/Supplemental Data
Dividend rate			6.50%				6.50%						6.50%	6.50%
Preferred Stock
Investment Company, Financial Highlights [Roll Forward]
Distributions of net investment income (in dollars per share)			$ (0.07)				$ (0.04)						$ (0.12)	$ (0.07)
Distributions of capital gains (in dollars per share)			0				0							0
Total distributions (in dollars per share)			(0.07)				(0.04)						(0.12)	(0.07)
Common Stock
Investment Company, Financial Highlights [Roll Forward]
Distributions of net investment income (in dollars per share)			(0.18)				(0.18)						(0.36)	(0.34)
Distributions of capital gains (in dollars per share)			0				0							(0.02)
Total distributions (in dollars per share)			$ (0.18)				$ (0.18)						$ (0.36)	$ (0.36)
Shares outstanding at end of period (in shares)			412,794,121	408,618,704	404,033,549		398,852,478	396,179,053	393,164,437				412,794,121	398,852,478
Ratios/Supplemental Data
Net assets at end of year			$ 413	$ 409	$ 404		$ 399	$ 396	$ 393				$ 413	$ 399