Financial Highlights (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2022		Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022		Dec. 31, 2021		Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021		Dec. 31, 2022		Dec. 31, 2021		Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018	Sep. 21, 2021	Sep. 20, 2021
Investment Company, Financial Highlights [Roll Forward]
Net asset value, beginning balance (in dollars per share)					$ 16.34	[1]					$ 15.50	[1]	$ 16.34	[1]	$ 15.50	[1]	$ 16.80	[1]	$ 17.38		$ 18.28
Net investment income (loss) (in dollars per share)													1.56	[2]	1.31	[2]	1.39	[2]	1.54		1.61
Net realized (loss) gain and net change in unrealized (depreciation) appreciation on investments and (loss) gain on foreign currency (in dollars per share)													(0.68)		0.79		(1.57)		(0.63)		(1.03)
Total net increase (decrease) (in dollars per share)													0.88		2.10		(0.18)		0.91		0.58
Shareholder distributions:
Distributions declared to stockholders from net investment income (in dollars per share)													(1.44)		(1.26)		(1.12)		(1.49)		(1.49)
Capital share transactions:
Issuance of common stock above net asset value (in dollars per share)													0		0		0		0		0.01
Repurchases of common stock (in dollars per share)													0.20		0		0		0		0
Net increase in net assets resulting from capital share transactions (in dollars per share)	$ 15.98		$ 16.26	$ 15.89	$ 16.20		$ 16.34		$ 16.52	$ 16.34	$ 16.12		0.20		0		0		0		0.01
Net asset value, ending balance (in dollars per share)	$ 15.98	[1]					$ 16.34	[1]					$ 15.98	[1]	$ 16.34	[1]	$ 15.50	[1]	$ 16.80	[1]	$ 17.38
Shares outstanding at end of period (in shares)	55,299,484	[1]					56,958,440	[1]					55,299,484	[1]	56,958,440	[1]	56,646,867	[1]	56,690,578		56,354,579	56,958,440	113,916,869
Total investment return-net value													10.44%		14.43%		(0.94%)		5.55%		2.98%
Total investment return-market asset value													(14.87%)		3.87%		0.00%		0.00%		0.00%
Net assets at beginning of period					$ 930,512	[3]					$ 878,256		$ 930,512	[3]	$ 878,256		$ 952,563		$ 979,271		$ 1,058,691
Net assets at end of period	$ 883,634						$ 930,512	[3]					883,634		930,512	[3]	878,256		952,563		979,271
Average net assets for the period	$ 917,781						$ 918,824						$ 917,781		$ 918,824		$ 875,846		$ 967,323		$ 1,035,861
Ratio/Supplemental data:
Ratio of net investment income to average net assets													9.61%		8.09%		8.99%		9.03%		8.71%
Ratio of gross operating expenses to average net assets													11.63%		9.04%		9.72%		11.76%		9.46%
Ratio of net operating expenses to average net assets													11.63%		9.04%		9.72%		11.76%		9.46%
Portfolio turnover													26.81%		52.04%		22.99%		31.59%		52.46%
Total amount of senior securities outstanding													$ 957,500		$ 830,000		$ 725,000		$ 841,042		$ 898,542
Asset coverage ratio	192000.00%						212000.00%						192000.00%		212000.00%		221000.00%		213000.00%		209000.00%
Issuance of shares, per share (in dollars per share)													$ 0.01		$ 0.01		$ 0.01		$ 0.01		$ 0.01
Repurchase of shares, per share (in dollars per share)															$ 0.01		$ 0.01		$ 0.01		$ 0.01
Number of shares (in shares)	1												1

[1] As discussed in Note 3, the Company completed a two-to-one reverse stock split, effective as of September 21, 2021. The shares outstanding used in the computation of net asset value per share reflect the reverse stock split on a retroactive basis.

[2] As discussed in Note 3, the Company completed a two-to-one reverse stock split, effective as of September 21, 2021. The weighted average shares used in the computation of the net increase (decrease) in net assets per share resulting from operations and net investment income per share reflect the reverse stock split on a retroactive basis.

[3] Fair value determined in good faith by the Company’s board of directors (see Note 9) using significant unobservable inputs unless otherwise noted.