Fair Value Measurements - Schedule of Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Sep. 30, 2024
Promissory note receivable from Founders | Carrying Value
Financial assets:
Notes receivable	$ 24,369	$ 15,722
Promissory note receivable from Founders | Estimated Fair Value
Financial assets:
Notes receivable	24,369	15,722
Promissory note receivable from Founders | Estimated Fair Value | Level 1
Financial assets:
Notes receivable	0	0
Promissory note receivable from Founders | Estimated Fair Value | Level 2
Financial assets:
Notes receivable	0	0
Promissory note receivable from Founders | Estimated Fair Value | Level 3
Financial assets:
Notes receivable	24,369	15,722
Investments in unconsolidated affiliates | Carrying Value
Financial assets:
Investments in unconsolidated affiliates	18,123	13,329
Investments in unconsolidated affiliates | Estimated Fair Value
Financial assets:
Investments in unconsolidated affiliates	59,729	42,496
Investments in unconsolidated affiliates | Estimated Fair Value | Level 1
Financial assets:
Investments in unconsolidated affiliates	58,573	41,646
Investments in unconsolidated affiliates | Estimated Fair Value | Level 2
Financial assets:
Investments in unconsolidated affiliates	0	0
Investments in unconsolidated affiliates | Estimated Fair Value | Level 3
Financial assets:
Investments in unconsolidated affiliates	1,156	850
2029 Convertible Notes | Carrying Value
Financial liabilities:
Debt instrument, fair value	225,258	224,256
2029 Convertible Notes | Estimated Fair Value
Financial liabilities:
Debt instrument, fair value	422,931	273,700
2029 Convertible Notes | Estimated Fair Value | Level 1
Financial liabilities:
Debt instrument, fair value	0	0
2029 Convertible Notes | Estimated Fair Value | Level 2
Financial liabilities:
Debt instrument, fair value	422,931	273,700
2029 Convertible Notes | Estimated Fair Value | Level 3
Financial liabilities:
Debt instrument, fair value	0	0
2032 Senior Notes | Carrying Value
Financial liabilities:
Debt instrument, fair value	292,818
2032 Senior Notes | Estimated Fair Value
Financial liabilities:
Debt instrument, fair value	320,734
2032 Senior Notes | Estimated Fair Value | Level 1
Financial liabilities:
Debt instrument, fair value	0
2032 Senior Notes | Estimated Fair Value | Level 2
Financial liabilities:
Debt instrument, fair value	320,734
2032 Senior Notes | Estimated Fair Value | Level 3
Financial liabilities:
Debt instrument, fair value	$ 0
2025 Convertible Notes | Carrying Value
Financial liabilities:
Debt instrument, fair value		103,072
2025 Convertible Notes | Estimated Fair Value
Financial liabilities:
Debt instrument, fair value		100,401
2025 Convertible Notes | Estimated Fair Value | Level 1
Financial liabilities:
Debt instrument, fair value		0
2025 Convertible Notes | Estimated Fair Value | Level 2
Financial liabilities:
Debt instrument, fair value		100,401
2025 Convertible Notes | Estimated Fair Value | Level 3
Financial liabilities:
Debt instrument, fair value		$ 0