Investments - Investments By Geographic Region (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Consolidated Schedule of Investments
Investments, amortized cost	$ 2,301,834	$ 2,419,938
Percentage of Total Portfolio	100.00%	100.00%
Market Value	$ 2,298,343	$ 2,386,977
Percentage of Total Portfolio	100.00%	100.00%
United States
Consolidated Schedule of Investments
Investments, amortized cost	$ 2,025,572	$ 2,113,220
Percentage of Total Portfolio	88.00%	87.30%
Market Value	$ 1,998,863	$ 2,076,143
Percentage of Total Portfolio	87.10%	87.00%
Cayman Islands
Consolidated Schedule of Investments
Investments, amortized cost	$ 124,504	$ 116,023
Percentage of Total Portfolio	5.40%	4.80%
Market Value	$ 133,072	$ 118,535
Percentage of Total Portfolio	5.80%	5.00%
United Kingdom
Consolidated Schedule of Investments
Investments, amortized cost	$ 40,119	$ 54,510
Percentage of Total Portfolio	1.70%	2.30%
Market Value	$ 39,035	$ 52,633
Percentage of Total Portfolio	1.70%	2.20%
Belgium
Consolidated Schedule of Investments
Investments, amortized cost	$ 39,439	$ 14,126
Percentage of Total Portfolio	1.70%	0.60%
Market Value	$ 53,619	$ 18,779
Percentage of Total Portfolio	2.30%	0.80%
Australia
Consolidated Schedule of Investments
Investments, amortized cost	$ 23,550	$ 50,981
Percentage of Total Portfolio	1.00%	2.10%
Market Value	$ 27,007	$ 51,947
Percentage of Total Portfolio	1.20%	2.20%
Germany
Consolidated Schedule of Investments
Investments, amortized cost	$ 24,677	$ 17,608
Percentage of Total Portfolio	1.10%	0.70%
Market Value	$ 23,326	$ 17,882
Percentage of Total Portfolio	1.00%	0.70%
Ireland
Consolidated Schedule of Investments
Investments, amortized cost	$ 9,394	$ 19,186
Percentage of Total Portfolio	0.40%	0.80%
Market Value	$ 10,001	$ 17,779
Percentage of Total Portfolio	0.40%	0.70%
Luxembourg
Consolidated Schedule of Investments
Investments, amortized cost	$ 8,145	$ 8,131
Percentage of Total Portfolio	0.40%	0.30%
Market Value	$ 7,512	$ 7,285
Percentage of Total Portfolio	0.30%	0.30%
Netherlands
Consolidated Schedule of Investments
Investments, amortized cost		$ 51
Percentage of Total Portfolio		0.00%
Market Value		$ 51
Percentage of Total Portfolio		0.00%
Canada
Consolidated Schedule of Investments
Investments, amortized cost	$ 5,844	$ 19,004
Percentage of Total Portfolio	0.30%	0.80%
Market Value	$ 5,340	$ 18,754
Percentage of Total Portfolio	0.20%	0.80%
Guernsey
Consolidated Schedule of Investments
Investments, amortized cost	$ 404	$ 6,573
Percentage of Total Portfolio	0.00%	0.30%
Market Value	$ 411	$ 6,687
Percentage of Total Portfolio	0.00%	0.30%
Sweden
Consolidated Schedule of Investments
Investments, amortized cost	$ 186	$ 185
Percentage of Total Portfolio	0.00%	0.00%
Market Value	$ 157	$ 158
Percentage of Total Portfolio	0.00%	0.00%
Israel
Consolidated Schedule of Investments
Investments, amortized cost		$ 340
Percentage of Total Portfolio		0.00%
Market Value		$ 344
Percentage of Total Portfolio		0.00%