Financial Highlights (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Investment Company, Financial Highlights [Roll Forward]
Net asset value at beginning of period (in dollars per share)			$ 23.09
Net asset value at end of period (in dollars per share)	$ 22.32	$ 23.14	$ 22.32	$ 23.14
Common shares outstanding at beginning of period (in shares)			196,721,000
Common shares outstanding at end of period (in shares)	191,612,000	182,204,000	191,612,000	182,204,000
Outstanding senior securities	$ 2,624,800	$ 2,409,400	$ 2,624,800	$ 2,409,400
Class I shares
Investment Company, Financial Highlights [Roll Forward]
Net asset value at beginning of period (in dollars per share)	$ 22.38	$ 23.28	$ 23.09	$ 23.56
Net investment income (in dollars per share)	0.47	0.46	1.46	1.50
Net unrealized appreciation (depreciation) (in dollars per share)	0	0.09	(0.53)	(0.08)
Net realized gains (losses) (in dollars per share)	(0.05)	(0.09)	(0.16)	(0.04)
Net increase (decrease) in net assets resulting from operations (in dollars per share)	0.42	0.46	0.77	1.38
Distributions of net investment income to shareholders (in dollars per share)	(0.47)	(0.46)	(1.46)	(1.50)
Distributions in excess of net investment income (in dollars per share)	(0.01)	(0.14)	(0.08)	(0.30)
Net asset value at end of period (in dollars per share)	$ 22.32	$ 23.14	$ 22.32	$ 23.14
Total return	1.89%	2.00%	3.44%	6.05%
Common shares outstanding at beginning of period (in shares)	142,336,000	110,042,000	139,709,000	89,884,000
Common shares outstanding at end of period (in shares)	137,453,000	127,124,000	137,453,000	127,124,000
Net assets at the beginning of the period	$ 3,185,463	$ 2,561,941	$ 3,225,643	$ 2,118,000
Net assets at end of period	3,068,587	2,942,033	3,068,587	2,942,033
Average net assets	$ 3,233,313	$ 3,010,527	$ 3,355,817	$ 2,578,139
Ratio of net investment income to average net assets	2.10%	2.02%	6.39%	6.41%
Ratio of total expenses to average net assets	1.73%	1.66%	5.07%	5.41%
Ratio of net expenses to average net assets	1.73%	1.66%	5.07%	5.41%
Ratio of portfolio turnover to average investments at fair value	12.13%	6.89%	29.57%	22.31%
Weighted average outstanding debt	$ 2,774,448	$ 2,042,351	$ 2,783,135	$ 2,027,190
Average debt per share (in dollars per share)	$ 13.94	$ 11.09	$ 13.58	$ 12.61
Asset coverage ratio	262.38%	275.22%	262.38%	275.22%
Class S shares
Investment Company, Financial Highlights [Roll Forward]
Net asset value at beginning of period (in dollars per share)	$ 22.38	$ 23.28	$ 23.09	$ 23.56
Net investment income (in dollars per share)	0.42	0.41	1.31	1.35
Net unrealized appreciation (depreciation) (in dollars per share)	0	0.09	(0.53)	(0.08)
Net realized gains (losses) (in dollars per share)	(0.05)	(0.09)	(0.16)	(0.04)
Net increase (decrease) in net assets resulting from operations (in dollars per share)	0.37	0.41	0.62	1.23
Distributions of net investment income to shareholders (in dollars per share)	(0.42)	(0.41)	(1.31)	(1.35)
Distributions in excess of net investment income (in dollars per share)	(0.01)	(0.14)	(0.08)	(0.30)
Net asset value at end of period (in dollars per share)	$ 22.32	$ 23.14	$ 22.32	$ 23.14
Total return	1.67%	1.79%	2.78%	5.38%
Common shares outstanding at beginning of period (in shares)	53,807,000	52,027,000	56,785,000	44,323,000
Common shares outstanding at end of period (in shares)	53,523,000	54,922,000	53,523,000	54,922,000
Net assets at the beginning of the period	$ 1,204,239	$ 1,211,427	$ 1,310,917	$ 1,044,424
Net assets at end of period	1,194,854	1,271,064	1,194,854	1,271,064
Average net assets	$ 1,223,968	$ 1,268,911	$ 1,301,760	$ 1,191,417
Ratio of net investment income to average net assets	1.89%	1.81%	5.77%	5.77%
Ratio of total expenses to average net assets	1.94%	1.87%	5.71%	6.01%
Ratio of net expenses to average net assets	1.94%	1.87%	5.71%	6.01%
Ratio of portfolio turnover to average investments at fair value	12.13%	6.89%	29.57%	22.31%
Weighted average outstanding debt	$ 2,774,448	$ 2,042,351	$ 2,783,135	$ 2,027,190
Average debt per share (in dollars per share)	$ 13.94	$ 11.09	$ 13.58	$ 12.61
Asset coverage ratio	262.38%	275.22%	262.38%	275.22%
Class D shares
Investment Company, Financial Highlights [Roll Forward]
Net asset value at beginning of period (in dollars per share)	$ 22.38	$ 23.28	$ 23.09	$ 23.56
Net investment income (in dollars per share)	0.46	0.45	1.42	1.46
Net unrealized appreciation (depreciation) (in dollars per share)	0	0.09	(0.53)	(0.08)
Net realized gains (losses) (in dollars per share)	(0.05)	(0.09)	(0.16)	(0.04)
Net increase (decrease) in net assets resulting from operations (in dollars per share)	0.41	0.45	0.73	1.34
Distributions of net investment income to shareholders (in dollars per share)	(0.46)	(0.45)	(1.42)	(1.46)
Distributions in excess of net investment income (in dollars per share)	(0.01)	(0.14)	(0.08)	(0.30)
Net asset value at end of period (in dollars per share)	$ 22.32	$ 23.14	$ 22.32	$ 23.14
Total return	1.82%	1.94%	3.24%	5.86%
Common shares outstanding at beginning of period (in shares)	400,000	157,000	174,000	81,000
Common shares outstanding at end of period (in shares)	400,000	158,000	400,000	158,000
Net assets at the beginning of the period	$ 8,959	$ 3,646	$ 4,028	$ 1,916
Net assets at end of period	8,929	3,663	8,929	3,663
Average net assets	$ 8,987	$ 3,665	$ 8,608	$ 3,046
Ratio of net investment income to average net assets	2.04%	1.97%	6.23%	6.25%
Ratio of total expenses to average net assets	1.80%	1.71%	5.25%	5.58%
Ratio of net expenses to average net assets	1.80%	1.71%	5.25%	5.58%
Ratio of portfolio turnover to average investments at fair value	12.13%	6.89%	29.57%	22.31%
Weighted average outstanding debt	$ 2,774,448	$ 2,042,351	$ 2,783,135	$ 2,027,190
Average debt per share (in dollars per share)	$ 13.94	$ 11.09	$ 13.58	$ 12.61
Asset coverage ratio	262.38%	275.22%	262.38%	275.22%
Class T shares
Investment Company, Financial Highlights [Roll Forward]
Net asset value at beginning of period (in dollars per share)	$ 22.38	$ 0	$ 23.09
Net investment income (in dollars per share)	0.42		1.31
Net unrealized appreciation (depreciation) (in dollars per share)	0		(0.53)
Net realized gains (losses) (in dollars per share)	(0.05)		(0.16)
Net increase (decrease) in net assets resulting from operations (in dollars per share)	0.37		0.62
Distributions of net investment income to shareholders (in dollars per share)	(0.42)		(1.31)
Distributions in excess of net investment income (in dollars per share)	(0.01)		(0.08)
Net asset value at end of period (in dollars per share)	$ 22.32	$ 0	$ 22.32	$ 0
Total return	1.67%		2.78%
Common shares outstanding at beginning of period (in shares)	179,000		53,000
Common shares outstanding at end of period (in shares)	236,000		236,000
Net assets at the beginning of the period	$ 4,008		$ 1,217
Net assets at end of period	5,274		5,274
Average net assets	$ 4,959		$ 3,942
Ratio of net investment income to average net assets	1.89%		5.77%
Ratio of total expenses to average net assets	1.94%		5.71%
Ratio of net expenses to average net assets	1.94%		5.71%
Ratio of portfolio turnover to average investments at fair value	12.13%		29.57%
Weighted average outstanding debt	$ 2,774,448		$ 2,783,135
Average debt per share (in dollars per share)	$ 13.94		$ 13.58
Asset coverage ratio	262.38%		262.38%