Investment - Additional Information (Details) - USD ($)	1 Months Ended		3 Months Ended		12 Months Ended
	Jun. 30, 2021	Jan. 31, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2021	Sep. 30, 2020	Jul. 13, 2020
Schedule Of Available For Sale Securities [Line Items]
Realized gains (losses)					$ (4,000)	$ 0
Short-term investments						$ 0
Short-term investments maturity due within one year					9,000,000.0
Short-term investments maturity due from October 2022 to March 2023					500,000
Estimated Fair Value					9,496,000
Proceeds from sale of investment in debt security					2,069,000
Gain on investments, net					$ 1,993,000
Debt Security
Schedule Of Available For Sale Securities [Line Items]
Proceeds from sale of investment in debt security	$ 1,800,000	$ 300,000
Additional cash compensation to be received based on conditions met		2,400,000
Repurchase price of bond if conditions not met		$ 1.00
Gain on investments, net			$ 1,700,000	$ 300,000
Reduction of additional cash compensation required from buyer to obtain rights to bond			$ 1,800,000
Debt Security | Third in Line lien on Assets | International Seismic Marine
Schedule Of Available For Sale Securities [Line Items]
Estimated Fair Value							$ 13,000,000.0
Unpaid invoices and later fees owed by customer							$ 13,000,000.0
Debt instrument, description					The bond was secured by a third in line lien on the assets owned by the customer and had an 8% interest rate with bi-annual interest and possible principal payments based on available excess cash flows.  Interest payments could be made either in cash or in-kind payments in the form of additional debt security.  In-kind interest payments require an 8.8% interest rate.
Investment interest rate							8.00%
In-kind payments, interest rate							8.80%
Maturity date							Jul. 13, 2022