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Investments - Additional Information (Details) - USD ($)	1 Months Ended		3 Months Ended			9 Months Ended
	Jun. 30, 2021	Jan. 31, 2021	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Sep. 30, 2020	Jul. 13, 2020
Schedule Of Available For Sale Securities [Line Items]
Realized gains (losses)			$ (1,000)		$ 0	$ (1,000)	$ 0
Short-term investments								$ 0
Proceeds from sale of investment in debt security						2,069,000
Gain on investments, net			1,727,000			$ 1,996,000
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 is secured by a third in line lien on the assets owned by the customer and has an 8% interest rate with bi-annual interest and possible principal payments based on available excess cash flows. Interest payments can 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
Minimum
Schedule Of Available For Sale Securities [Line Items]
Short-term investments maturity date	Sep. 30, 2021		Sep. 30, 2021			Sep. 30, 2021
Maximum
Schedule Of Available For Sale Securities [Line Items]
Short-term investments maturity date	Sep. 30, 2022		Sep. 30, 2022			Sep. 30, 2022