Fair Value of Financial Assets and Liabilities - Fair Value Measurements of the Company's Outstanding Series 1 Nonconvertible Preferred Stock (Detail) - Level 3 [Member] - Series 1 Nonconvertible Preferred Stock [Member]	Jun. 30, 2023	Sep. 30, 2022
Probabilities of Payout [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Range	0	0
Probabilities of Payout [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Range	65	65
Discount Rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Range	7.25	7.25