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Summary of Significant Accounting Policies - Revenue Recognition and Concentrations of Credit Risk - Additional Information (Detail) $ in Thousands	12 Months Ended
	Sep. 30, 2020 USD ($) Customer	Sep. 30, 2019 USD ($) Customer
Concentration Risk [Line Items]
Number of customers with an account receivable balance of more than 10% of total accounts receivable | Customer	1	1
Allowance for doubtful accounts | $	$ 23,419	$ 36,121
Accounts Receivable [Member] | Customer [Member]
Concentration Risk [Line Items]
Aggregate account receivable of more than 10% of total accounts receivable	22.00%	16.00%

X

- Definition

Number Of Customers With Accounts Receivable Balance Of More Than Stated Percentage Of Accounts Receivables

+ References

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Amount of allowance for credit loss on accounts receivable, classified as current.

+ References

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