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Convertible Notes - Additional Information (Detail)			1 Months Ended		3 Months Ended	9 Months Ended		23 Months Ended
	Aug. 13, 2020 USD ($) shares $ / shares	Jun. 16, 2020 USD ($) shares $ / shares	May 20, 2023	Jun. 30, 2020 USD ($)	Sep. 30, 2020 USD ($) $ / shares	Sep. 30, 2020 USD ($) $ / shares shares	Sep. 30, 2019 USD ($)	May 21, 2023 Day
Convertible Senior Notes [Line Items]
Payments for stock repurchase						$ 30,979,000	$ 2,187,000
Debt instrument convertible threshold percentage of stock price trigger			130.00%
Interest expense					$ 2,511,000	2,888,000
Conversion Rate Increase [Member]
Convertible Senior Notes [Line Items]
Principal amount of the convertible notes				$ 1,000
Accounts Payable and Accrued Liabilities [Member]
Convertible Senior Notes [Line Items]
Interest payable					2,173,000	2,173,000
Convertible Senior Notes Due Two Thousand And Twenty Three [Member]
Convertible Senior Notes [Line Items]
Convertible senior notes face value					$ 175,000,000	175,000,000
Convertible debt equity component						5,059,000
Issuance costs allocated to equity component of convertible debt						$ 157,000
Convertible Senior Notes Due Two Thousand And Twenty Three [Member] | Fair Value, Inputs, Level 2 [Member]
Convertible Senior Notes [Line Items]
Fair value of debt component at issuance date	$ 170,191,000	$ 170,191,000
Convertible notes discount rate					5.33	5.33
Fair value of debt component of convertible senior notes					$ 167,153,000	$ 167,153,000
Convertible Senior Notes Due Two Thousand And Twenty Three [Member] | Private Placement [Member]
Convertible Senior Notes [Line Items]
Convertible senior notes face value	$ 25,000,000	$ 150,000,000
Convertible senior notes stated rate of interest	4.25%	4.25%
Covertible senior notes year of maturity	2023	2023
Payments for stock repurchase						$ 28,297,000
Repurchased common stock, shares | shares						7,487,335
Repurchase price per share | $ / shares					$ 3.78	$ 3.78
Convertible senior notes maturity date					Jun. 15, 2023	Jun. 15, 2023
Redemption provisions - Convertible notes redemption price as a percentage of principal amount accrued interest and unpaid interest	100.00%	100.00%
Debt instrument percentage of principal amount due to lenders entitled to declare repurchase	25.00%	25.00%
Convertible Senior Notes Due Two Thousand And Twenty Three [Member] | Private Placement [Member] | Conversion Price [Member]
Convertible Senior Notes [Line Items]
Convertible debt instrument conversion price | $ / shares	$ 5.92	$ 5.92
Convertible debt instrument terms of conversion	Convertible at an initial conversion rate of 168.9189 shares of the Company’s common stock, per $1,000 principal amount of notes	Convertible at an initial conversion rate of 168.9189 shares of the Company’s common stock, per $1,000 principal amount of notes
Convertible Senior Notes Due Two Thousand And Twenty Three [Member] | Private Placement [Member] | Redemption Provisions [Member]
Convertible Senior Notes [Line Items]
Redemption provisions - Convertible notes	Redemption price of $7.70: The Company may redeem for cash all or any portion of the notes, at its option, on or after June 20, 2021 and on or prior to the 55th scheduled trading day immediately preceding the maturity date, if the last reported sale price of the Company's common stock has been at least 130% of the conversion price then in effect for at least 20 trading days, including the trading day immediately preceding the date on which the Company provides notice of redemption, during any 30 consecutive trading day period ending on, and including, the trading day immediately preceding the date on which the Company provides notice of redemption, at a redemption price equal to 100% of the principal amount of the notes to be redeemed, plus accrued and unpaid interest to, but excluding the redemption date. No sinking fund is provided for the Convertible Notes.	Redemption price of $7.70: The Company may redeem for cash all or any portion of the notes, at its option, on or after June 20, 2021 and on or prior to the 55th scheduled trading day immediately preceding the maturity date, if the last reported sale price of the Company's common stock has been at least 130% of the conversion price then in effect for at least 20 trading days, including the trading day immediately preceding the date on which the Company provides notice of redemption, during any 30 consecutive trading day period ending on, and including, the trading day immediately preceding the date on which the Company provides notice of redemption, at a redemption price equal to 100% of the principal amount of the notes to be redeemed, plus accrued and unpaid interest to, but excluding the redemption date. No sinking fund is provided for the Convertible Notes.
Convertible Senior Notes Due Two Thousand And Twenty Three [Member] | Private Placement [Member] | Conversion Rate Increase [Member]
Convertible Senior Notes [Line Items]
Maximum Conversion Rate	270.2702	270.2702
Maximum number of shares issuable upon conversion | shares	47,297,285	47,297,285
Convertible Senior Notes Due Two Thousand And Twenty Three [Member] | Private Placement [Member] | Scenario, Forecast [Member]
Convertible Senior Notes [Line Items]
Redemption provisions - Convertible notes, threshold trading days | Day								20
Redemption provisions - Convertible notes, threshold consecutive trading days | Day								30
US National Bank Association [Member] | Convertible Senior Notes Due Two Thousand And Twenty Three [Member] | Private Placement [Member] | Redemption Provisions [Member]
Convertible Senior Notes [Line Items]
Redemption provisions - Convertible notes redemption price as a percentage of principal amount accrued interest and unpaid interest		100.00%

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Amount of increase (decrease) in additional paid in capital (APIC) resulting from recognition of deferred taxes for convertible debt with a beneficial conversion feature.

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