Investments - Schedules of Portfolio Composition by Geographic Region at Amortization Cost and Fair Value (Details) - USD ($)
$ in Thousands |
12 Months Ended |
Sep. 30, 2025 |
Sep. 30, 2024 |
| Schedule of Investments [Line Items] |
|
|
|
|
| Amortized Cost |
$ 2,176,447
|
|
$ 1,291,512
|
|
| Fair Value |
$ 2,209,174
|
[1] |
$ 1,311,001
|
[2] |
| Investments, at Amortized Cost | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
100.00%
|
|
100.00%
|
|
| Investments, at Fair Value | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
100.00%
|
|
100.00%
|
|
| Midwest |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Amortized Cost |
$ 395,386
|
|
$ 260,483
|
|
| Fair Value |
$ 401,851
|
|
$ 264,441
|
|
| Midwest | Investments, at Amortized Cost | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
18.20%
|
|
20.20%
|
|
| Midwest | Investments, at Fair Value | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
18.20%
|
|
20.20%
|
|
| West |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Amortized Cost |
$ 369,906
|
|
$ 256,337
|
|
| Fair Value |
$ 374,368
|
|
$ 260,330
|
|
| West | Investments, at Amortized Cost | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
17.00%
|
|
19.80%
|
|
| West | Investments, at Fair Value | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
16.90%
|
|
19.90%
|
|
| Southeast |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Amortized Cost |
$ 445,901
|
|
$ 205,574
|
|
| Fair Value |
$ 449,900
|
|
$ 207,853
|
|
| Southeast | Investments, at Amortized Cost | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
20.50%
|
|
15.90%
|
|
| Southeast | Investments, at Fair Value | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
20.40%
|
|
15.80%
|
|
| Southwest |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Amortized Cost |
$ 255,497
|
|
$ 149,845
|
|
| Fair Value |
$ 258,152
|
|
$ 151,420
|
|
| Southwest | Investments, at Amortized Cost | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
11.70%
|
|
11.60%
|
|
| Southwest | Investments, at Fair Value | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
11.70%
|
|
11.50%
|
|
| Mid-Atlantic |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Amortized Cost |
$ 285,602
|
|
$ 199,479
|
|
| Fair Value |
$ 288,569
|
|
$ 201,474
|
|
| Mid-Atlantic | Investments, at Amortized Cost | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
13.10%
|
|
15.40%
|
|
| Mid-Atlantic | Investments, at Fair Value | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
13.10%
|
|
15.40%
|
|
| Northeast |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Amortized Cost |
$ 144,153
|
|
$ 130,402
|
|
| Fair Value |
$ 145,343
|
|
$ 132,136
|
|
| Northeast | Investments, at Amortized Cost | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
6.60%
|
|
10.10%
|
|
| Northeast | Investments, at Fair Value | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
6.60%
|
|
10.10%
|
|
| United Kingdom |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Amortized Cost |
$ 140,614
|
|
$ 40,106
|
|
| Fair Value |
$ 143,807
|
|
$ 42,123
|
|
| United Kingdom | Investments, at Amortized Cost | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
6.50%
|
|
3.10%
|
|
| United Kingdom | Investments, at Fair Value | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
6.50%
|
|
3.20%
|
|
| Germany |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Amortized Cost |
$ 53,904
|
|
$ 39,463
|
|
| Fair Value |
$ 58,632
|
|
$ 41,091
|
|
| Germany | Investments, at Amortized Cost | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
2.50%
|
|
3.10%
|
|
| Germany | Investments, at Fair Value | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
2.70%
|
|
3.10%
|
|
| Canada |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Amortized Cost |
$ 20,172
|
|
$ 0
|
|
| Fair Value |
$ 20,437
|
|
$ 0
|
|
| Canada | Investments, at Amortized Cost | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
0.90%
|
|
0.00%
|
|
| Canada | Investments, at Fair Value | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
0.90%
|
|
0.00%
|
|
| Australia |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Amortized Cost |
$ 25,160
|
|
$ 0
|
|
| Fair Value |
$ 25,855
|
|
$ 0
|
|
| Australia | Investments, at Amortized Cost | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
1.20%
|
|
0.00%
|
|
| Australia | Investments, at Fair Value | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
1.20%
|
|
0.00%
|
|
| Jersey |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Amortized Cost |
$ 20,433
|
|
$ 0
|
|
| Fair Value |
$ 21,123
|
|
$ 0
|
|
| Jersey | Investments, at Amortized Cost | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
1.00%
|
|
0.00%
|
|
| Jersey | Investments, at Fair Value | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
1.00%
|
|
0.00%
|
|
| Finland |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Amortized Cost |
$ 6,987
|
|
$ 0
|
|
| Fair Value |
$ 7,561
|
|
$ 0
|
|
| Finland | Investments, at Amortized Cost | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
0.30%
|
|
0.00%
|
|
| Finland | Investments, at Fair Value | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
0.30%
|
|
0.00%
|
|
| Sweden |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Amortized Cost |
$ 5,264
|
|
$ 4,919
|
|
| Fair Value |
$ 5,459
|
|
$ 5,064
|
|
| Sweden | Investments, at Amortized Cost | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
0.20%
|
|
0.40%
|
|
| Sweden | Investments, at Fair Value | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
0.20%
|
|
0.40%
|
|
| Netherlands |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Amortized Cost |
$ 4,250
|
|
$ 1,256
|
|
| Fair Value |
$ 4,621
|
|
$ 1,321
|
|
| Netherlands | Investments, at Amortized Cost | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
0.20%
|
|
0.10%
|
|
| Netherlands | Investments, at Fair Value | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
0.20%
|
|
0.10%
|
|
| France |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Amortized Cost |
$ 2,281
|
|
$ 2,013
|
|
| Fair Value |
$ 2,497
|
|
$ 2,072
|
|
| France | Investments, at Amortized Cost | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
0.10%
|
|
0.20%
|
|
| France | Investments, at Fair Value | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
0.10%
|
|
0.20%
|
|
| Denmark |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Amortized Cost |
$ 544
|
|
$ 541
|
|
| Fair Value |
$ 545
|
|
$ 554
|
|
| Denmark | Investments, at Amortized Cost | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
0.00%
|
|
0.00%
|
|
| Denmark | Investments, at Fair Value | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
0.00%
|
|
0.00%
|
|
| Luxembourg |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Amortized Cost |
$ 312
|
|
$ 1,013
|
|
| Fair Value |
$ 331
|
|
$ 1,016
|
|
| Luxembourg | Investments, at Amortized Cost | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
0.00%
|
|
0.10%
|
|
| Luxembourg | Investments, at Fair Value | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
0.00%
|
|
0.10%
|
|
| Israel |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Amortized Cost |
$ 81
|
|
$ 81
|
|
| Fair Value |
$ 123
|
|
$ 106
|
|
| Israel | Investments, at Amortized Cost | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
0.00%
|
|
0.00%
|
|
| Israel | Investments, at Fair Value | Geographic Concentration Risk |
|
|
|
|
| Schedule of Investments [Line Items] |
|
|
|
|
| Concentration risk, percentage |
0.00%
|
|
0.00%
|
|
|
|