Fair Value Measurements - Summary of Changes in Fair Value of Investments Measured Using Level 3 Inputs (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024	Dec. 31, 2023
Total Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	$ 12,602,272	$ 10,330,365	$ 12,976,765	$ 9,710,582
Purchases of investments	717,597	739,127
Proceeds from principal repayments and sales of investments	(997,993)	(186,370)
Accretion of discount (amortization of premium)	16,085	9,375
Transfers into level 3	225	50,239
Transfers out of level 3	(102,175)	0
Fair value, end of period	12,602,272	10,330,365
Net change in unrealized appreciation (depreciation) included in earnings related to financial instruments, included in net unrealized appreciation (depreciation) on the condensed consolidated statements of operations	(8,405)	7,674
Investments, Realized Gain (Loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Net realized gain (loss)	8,525	428
Investments, Unrealized Gain (Loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Net realized gain (loss)	(16,757)	6,984
First lien debt
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	12,370,969	10,178,311	12,714,636	9,564,203
Purchases of investments	715,298	734,974
Proceeds from principal repayments and sales of investments	(964,827)	(186,370)
Accretion of discount (amortization of premium)	16,001	9,341
Transfers into level 3	225	50,239
Transfers out of level 3	(102,175)	0
Fair value, end of period	12,370,969	10,178,311
Net change in unrealized appreciation (depreciation) included in earnings related to financial instruments, included in net unrealized appreciation (depreciation) on the condensed consolidated statements of operations	(5,329)	6,191
Debt Securities, First Lien, Realized Gain (Loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Net realized gain (loss)	1,210	428
Debt Securities, First Lien, Unrealized Gain (Loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Net realized gain (loss)	(9,399)	5,496
Second lien debt
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	118,482	41,515	119,184	41,515
Purchases of investments	1,663	180
Proceeds from principal repayments and sales of investments	(2,347)	0
Accretion of discount (amortization of premium)	74	25
Transfers into level 3	0	0
Transfers out of level 3	0	0
Fair value, end of period	118,482	41,515
Net change in unrealized appreciation (depreciation) included in earnings related to financial instruments, included in net unrealized appreciation (depreciation) on the condensed consolidated statements of operations	(91)	(205)
Debt Securities, Second Lien, Realized Gain (Loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Net realized gain (loss)	(1)	0
Debt Securities, Second Lien, Unrealized Gain (Loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Net realized gain (loss)	(91)	(205)
Unsecured debt
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	13,658	11,859	33,521	9,924
Purchases of investments	468	1,785
Proceeds from principal repayments and sales of investments	(20,595)	0
Accretion of discount (amortization of premium)	10	9
Transfers into level 3	0	0
Transfers out of level 3	0	0
Fair value, end of period	13,658	11,859
Net change in unrealized appreciation (depreciation) included in earnings related to financial instruments, included in net unrealized appreciation (depreciation) on the condensed consolidated statements of operations	(16)	135
Unsecured Debt, Realized Gain (Loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Net realized gain (loss)	0	0
Unsecured Debt, Unrealized Gain (Loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Net realized gain (loss)	254	141
Investments in equity
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	99,163	98,680	$ 109,424	$ 94,940
Purchases of investments	168	2,188
Proceeds from principal repayments and sales of investments	(10,224)	0
Accretion of discount (amortization of premium)	0	0
Transfers into level 3	0	0
Transfers out of level 3	0	0
Fair value, end of period	99,163	98,680
Net change in unrealized appreciation (depreciation) included in earnings related to financial instruments, included in net unrealized appreciation (depreciation) on the condensed consolidated statements of operations	(2,969)	1,553
Equity Securities, Realized Gain (Loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Net realized gain (loss)	7,316	0
Equity Securities, Unrealized Gain (Loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Net realized gain (loss)	$ (7,521)	$ 1,552