Fair Value Measurements and Derivative Instruments - Fair Value Hierarchy of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	$ 48,959,003	$ 30,795,693
First lien debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value		28,143,451
Second lien debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value		1,813,872
Unsecured debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value		5,842
Structured finance obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value		286,610
Equity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value		545,918
Level 1, Level 2, and Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	47,102,764
Level 1, Level 2, and Level 3 | First lien debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	43,902,022
Level 1, Level 2, and Level 3 | Second lien debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	2,111,420
Level 1, Level 2, and Level 3 | Unsecured debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	17,370
Level 1, Level 2, and Level 3 | Structured finance obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	357,384
Level 1, Level 2, and Level 3 | Equity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	714,568
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Level 1 | First lien debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Level 1 | Second lien debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Level 1 | Unsecured debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Level 1 | Structured finance obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Level 1 | Equity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	9,207,556	6,197,541
Level 2 | First lien debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	8,278,199	5,096,942
Level 2 | Second lien debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	842,501	1,013,739
Level 2 | Unsecured debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	17,370	5,842
Level 2 | Structured finance obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	69,486	81,018
Level 2 | Equity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	37,895,208	24,598,152
Level 3 | First lien debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	35,623,823	23,046,509
Level 3 | Second lien debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	1,268,919	800,133
Level 3 | Unsecured debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	0	0
Level 3 | Structured finance obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	287,898	205,592
Level 3 | Equity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	714,568	$ 545,918
NAV
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	$ 1,856,239