Portfolio Investments - Schedule of Roll-Forward in the Changes in Fair Value (Details) - USD ($)
$ in Thousands |
3 Months Ended |
9 Months Ended |
Jun. 30, 2025 |
Jun. 30, 2024 |
Jun. 30, 2025 |
Jun. 30, 2024 |
| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |
|
|
|
|
| Fair value, beginning balance |
$ 2,552,861
|
$ 2,667,425
|
$ 2,723,732
|
$ 2,619,912
|
| Purchases |
140,665
|
224,605
|
567,786
|
713,464
|
| Sales and repayments |
(221,661)
|
(113,234)
|
(682,652)
|
(512,974)
|
| Transfers in |
7,617
|
|
17,281
|
63,237
|
| Transfers out |
(19,490)
|
|
(85,119)
|
(44,643)
|
| Capitalized PIK interest income |
5,070
|
6,901
|
15,359
|
19,256
|
| Accretion of OID |
3,798
|
2,949
|
11,106
|
9,083
|
| Fair value, ending balance |
2,485,322
|
2,752,039
|
2,485,322
|
2,752,039
|
| Net unrealized appreciation (depreciation) relating to Level 3 investments still held and reported within net unrealized appreciation (depreciation) in the Consolidated Statement of Operations |
$ 15,018
|
$ (51,050)
|
$ (92,908)
|
$ (80,128)
|
| Unrealized gain (loss), location |
Gain (Loss), Investment and Derivative, Operating, and Foreign Currency Transaction, after Tax
|
Gain (Loss), Investment and Derivative, Operating, and Foreign Currency Transaction, after Tax
|
Gain (Loss), Investment and Derivative, Operating, and Foreign Currency Transaction, after Tax
|
Gain (Loss), Investment and Derivative, Operating, and Foreign Currency Transaction, after Tax
|
| Net unrealized appreciation (depreciation) |
|
|
|
|
| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |
|
|
|
|
| Total gains or losses included in earnings |
$ 17,692
|
$ 32,498
|
$ (64,520)
|
$ (26,992)
|
| Gain (loss), location |
Net unrealized appreciation (depreciation)
|
Net unrealized appreciation (depreciation)
|
Net unrealized appreciation (depreciation)
|
Net unrealized appreciation (depreciation)
|
| Net realized gains (losses) |
|
|
|
|
| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |
|
|
|
|
| Total gains or losses included in earnings |
$ (1,230)
|
$ (69,105)
|
$ (17,651)
|
$ (88,304)
|
| Gain (loss), location |
Realized gain (loss)
|
Realized gain (loss)
|
Realized gain (loss)
|
Realized gain (loss)
|
| Senior secured debt |
|
|
|
|
| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |
|
|
|
|
| Fair value, beginning balance |
$ 2,165,740
|
$ 2,327,422
|
$ 2,320,310
|
$ 2,292,691
|
| Purchases |
140,532
|
193,956
|
564,070
|
656,630
|
| Sales and repayments |
(219,233)
|
(113,234)
|
(679,251)
|
(506,977)
|
| Transfers in |
0
|
|
6,555
|
23,535
|
| Transfers out |
(19,080)
|
|
(84,709)
|
(38,544)
|
| Capitalized PIK interest income |
4,357
|
6,287
|
13,258
|
17,571
|
| Accretion of OID |
3,377
|
2,600
|
9,911
|
8,099
|
| Fair value, ending balance |
2,076,845
|
2,393,159
|
2,076,845
|
2,393,159
|
| Net unrealized appreciation (depreciation) relating to Level 3 investments still held and reported within net unrealized appreciation (depreciation) in the Consolidated Statement of Operations |
(183)
|
(36,501)
|
(84,243)
|
(54,217)
|
| Investment exchanged, cost |
7,200
|
|
30,900
|
38,500
|
| Senior secured debt | Net unrealized appreciation (depreciation) |
|
|
|
|
| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |
|
|
|
|
| Total gains or losses included in earnings |
1,892
|
7,640
|
(57,013)
|
(10,702)
|
| Senior secured debt | Net realized gains (losses) |
|
|
|
|
| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |
|
|
|
|
| Total gains or losses included in earnings |
(740)
|
(31,512)
|
(16,286)
|
(49,144)
|
| Subordinated debt |
|
|
|
|
| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |
|
|
|
|
| Fair value, beginning balance |
256,925
|
200,115
|
255,346
|
189,724
|
| Purchases |
0
|
30,480
|
3,583
|
47,507
|
| Sales and repayments |
(64)
|
0
|
(229)
|
(4,932)
|
| Transfers in |
0
|
|
0
|
0
|
| Transfers out |
0
|
|
0
|
(4,657)
|
| Capitalized PIK interest income |
713
|
614
|
2,101
|
1,685
|
| Accretion of OID |
421
|
349
|
1,195
|
984
|
| Fair value, ending balance |
257,498
|
230,484
|
257,498
|
230,484
|
| Net unrealized appreciation (depreciation) relating to Level 3 investments still held and reported within net unrealized appreciation (depreciation) in the Consolidated Statement of Operations |
(497)
|
(1,074)
|
(4,498)
|
(454)
|
| Subordinated debt | Net unrealized appreciation (depreciation) |
|
|
|
|
| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |
|
|
|
|
| Total gains or losses included in earnings |
(497)
|
(1,074)
|
(4,498)
|
127
|
| Subordinated debt | Net realized gains (losses) |
|
|
|
|
| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |
|
|
|
|
| Total gains or losses included in earnings |
0
|
0
|
0
|
46
|
| Preferred equity |
|
|
|
|
| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |
|
|
|
|
| Fair value, beginning balance |
70,147
|
62,602
|
66,320
|
86,057
|
| Purchases |
109
|
0
|
109
|
7,578
|
| Sales and repayments |
0
|
0
|
(587)
|
(205)
|
| Transfers in |
410
|
|
1,056
|
0
|
| Transfers out |
0
|
|
0
|
(1,159)
|
| Capitalized PIK interest income |
0
|
0
|
0
|
0
|
| Accretion of OID |
0
|
0
|
0
|
0
|
| Fair value, ending balance |
73,232
|
63,892
|
73,232
|
63,892
|
| Net unrealized appreciation (depreciation) relating to Level 3 investments still held and reported within net unrealized appreciation (depreciation) in the Consolidated Statement of Operations |
2,559
|
1,287
|
6,342
|
3,276
|
| Investment exchanged, cost |
|
|
600
|
4,700
|
| Preferred equity | Net unrealized appreciation (depreciation) |
|
|
|
|
| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |
|
|
|
|
| Total gains or losses included in earnings |
2,566
|
38,883
|
6,997
|
9,214
|
| Preferred equity | Net realized gains (losses) |
|
|
|
|
| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |
|
|
|
|
| Total gains or losses included in earnings |
0
|
(37,593)
|
(663)
|
(37,593)
|
| Common equity and warrants |
|
|
|
|
| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |
|
|
|
|
| Fair value, beginning balance |
60,049
|
77,286
|
81,756
|
51,440
|
| Purchases |
24
|
169
|
24
|
1,749
|
| Sales and repayments |
(2,364)
|
0
|
(2,585)
|
(860)
|
| Transfers in |
7,207
|
|
9,670
|
39,702
|
| Transfers out |
(410)
|
|
(410)
|
(283)
|
| Capitalized PIK interest income |
0
|
0
|
0
|
0
|
| Accretion of OID |
0
|
0
|
0
|
0
|
| Fair value, ending balance |
77,747
|
64,504
|
77,747
|
64,504
|
| Net unrealized appreciation (depreciation) relating to Level 3 investments still held and reported within net unrealized appreciation (depreciation) in the Consolidated Statement of Operations |
13,139
|
(14,762)
|
(10,509)
|
(28,733)
|
| Investment exchanged, cost |
400
|
|
9,700
|
1,200
|
| Common equity and warrants | Net unrealized appreciation (depreciation) |
|
|
|
|
| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |
|
|
|
|
| Total gains or losses included in earnings |
13,731
|
(12,951)
|
(10,006)
|
(25,631)
|
| Common equity and warrants | Net realized gains (losses) |
|
|
|
|
| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |
|
|
|
|
| Total gains or losses included in earnings |
(490)
|
$ 0
|
(702)
|
(1,613)
|
| Investment, Change in Market Quotes or Liquidity |
|
|
|
|
| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |
|
|
|
|
| Transfers in |
$ 11,900
|
|
6,600
|
18,900
|
| Transfers out |
|
|
(43,500)
|
|
| Common Stock |
|
|
|
|
| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |
|
|
|
|
| Investment exchanged, cost |
|
|
$ 400
|
$ 300
|