Investments - Geographic Investment (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Schedule of Investments [Line Items]
Cost	$ 48,875,505	$ 49,935,296
Fair Value	$ 48,413,196	$ 48,908,608
Fair Value as % of Net Assets	185.14%	215.60%
Investments At Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value	100.00%	100.00%
United States
Schedule of Investments [Line Items]
Cost	$ 44,201,063	$ 45,326,287
Fair Value	$ 43,848,229	$ 44,468,163
Fair Value as % of Net Assets	167.68%	196.02%
United States | Investments At Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value	90.57%	90.92%
Europe
Schedule of Investments [Line Items]
Cost	$ 3,557,527	$ 3,385,990
Fair Value	$ 3,496,679	$ 3,308,990
Fair Value as % of Net Assets	13.37%	14.59%
Europe | Investments At Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value	7.22%	6.77%
Canada
Schedule of Investments [Line Items]
Cost	$ 690,164	$ 795,999
Fair Value	$ 656,520	$ 748,234
Fair Value as % of Net Assets	2.51%	3.30%
Canada | Investments At Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value	1.36%	1.53%
Bermuda/Cayman Islands
Schedule of Investments [Line Items]
Cost	$ 402,986	$ 403,356
Fair Value	$ 388,640	$ 359,125
Fair Value as % of Net Assets	1.49%	1.58%
Bermuda/Cayman Islands | Investments At Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value	0.80%	0.73%
Australia/New Zealand
Schedule of Investments [Line Items]
Cost	$ 23,765	$ 23,664
Fair Value	$ 23,128	$ 24,096
Fair Value as % of Net Assets	0.09%	0.11%
Australia/New Zealand | Investments At Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value	0.05%	0.05%