Fair Value Measurements - Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Apr. 30, 2019	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Mar. 31, 2019
2.89% promissory note receivable due April 2024
Financial assets:
Notes receivable	$ 1,100				$ 1,100
Financial liabilities:
Interest on note receivable	2.89%	2.89%	2.89%
2.89% promissory note receivable due April 2024 | Carrying Value
Financial assets:
Notes receivable		$ 1,251	$ 1,215
2.89% promissory note receivable due April 2024 | Estimated Fair Value
Financial assets:
Notes receivable		1,251	1,215
2.89% promissory note receivable due April 2024 | Estimated Fair Value | Level 1
Financial assets:
Notes receivable		0	0
2.89% promissory note receivable due April 2024 | Estimated Fair Value | Level 2
Financial assets:
Notes receivable		0	0
2.89% promissory note receivable due April 2024 | Estimated Fair Value | Level 3
Financial assets:
Notes receivable		$ 1,251	1,215
12.00% promissory note receivable from Founders
Financial assets:
Notes receivable				$ 15,000
Financial liabilities:
Interest on note receivable		12.00%
12.00% promissory note receivable from Founders | Carrying Value
Financial assets:
Notes receivable		$ 16,500
12.00% promissory note receivable from Founders | Estimated Fair Value
Financial assets:
Notes receivable		16,500
12.00% promissory note receivable from Founders | Estimated Fair Value | Level 1
Financial assets:
Notes receivable		0
12.00% promissory note receivable from Founders | Estimated Fair Value | Level 2
Financial assets:
Notes receivable		0
12.00% promissory note receivable from Founders | Estimated Fair Value | Level 3
Financial assets:
Notes receivable		16,500
Investments in unconsolidated affiliate | Carrying Value
Financial assets:
Investments in unconsolidated affiliate		10,987	37,733
Investments in unconsolidated affiliate | Estimated Fair Value
Financial assets:
Investments in unconsolidated affiliate		35,998	40,279
Investments in unconsolidated affiliate | Estimated Fair Value | Level 1
Financial assets:
Investments in unconsolidated affiliate		35,998	40,279
Investments in unconsolidated affiliate | Estimated Fair Value | Level 2
Financial assets:
Investments in unconsolidated affiliate		0	0
Investments in unconsolidated affiliate | Estimated Fair Value | Level 3
Financial assets:
Investments in unconsolidated affiliate		0	0
2024 Convertible Notes | Carrying Value
Financial liabilities:
Debt instrument, fair value		34,265	142,575
2024 Convertible Notes | Estimated Fair Value
Financial liabilities:
Debt instrument, fair value		35,765	157,727
2024 Convertible Notes | Estimated Fair Value | Level 1
Financial liabilities:
Debt instrument, fair value		0	0
2024 Convertible Notes | Estimated Fair Value | Level 2
Financial liabilities:
Debt instrument, fair value		35,765	157,727
2024 Convertible Notes | Estimated Fair Value | Level 3
Financial liabilities:
Debt instrument, fair value		0	0
2025 Convertible Notes | Carrying Value
Financial liabilities:
Debt instrument, fair value		102,563	170,328
2025 Convertible Notes | Estimated Fair Value
Financial liabilities:
Debt instrument, fair value		96,137	147,488
2025 Convertible Notes | Estimated Fair Value | Level 1
Financial liabilities:
Debt instrument, fair value		0	0
2025 Convertible Notes | Estimated Fair Value | Level 2
Financial liabilities:
Debt instrument, fair value		96,137	147,488
2025 Convertible Notes | Estimated Fair Value | Level 3
Financial liabilities:
Debt instrument, fair value		0	$ 0
2029 Convertible Notes | Carrying Value
Financial liabilities:
Debt instrument, fair value		223,284
2029 Convertible Notes | Estimated Fair Value
Financial liabilities:
Debt instrument, fair value		224,112
2029 Convertible Notes | Estimated Fair Value | Level 1
Financial liabilities:
Debt instrument, fair value		0
2029 Convertible Notes | Estimated Fair Value | Level 2
Financial liabilities:
Debt instrument, fair value		224,112
2029 Convertible Notes | Estimated Fair Value | Level 3
Financial liabilities:
Debt instrument, fair value		$ 0