Commitments and Contingencies - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended		36 Months Ended
	Dec. 31, 2020	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2024	Sep. 30, 2020
Commitments And Contingencies [Line Items]
Payments to acquire intangible assets	$ 1,000,000
Other accrued liabilities current	4,086,000					$ 5,547,000
Other long-term liabilities	7,630,000					8,020,000
Embolitech LLC [Member]
Commitments And Contingencies [Line Items]
Payments to acquire in-process research and development		$ 1,000,000.0		$ 5,000,000.0
Contingent payments upon achievement of regulatory milestones	$ 1,000,000.0
Installment payment beginning period	2022
Installment payment ending period	2024
CRO [Member]
Commitments And Contingencies [Line Items]
Contractual obligation remaining to be paid	$ 9,000,000
CRO [Member] | Minimum [Member]
Commitments And Contingencies [Line Items]
Gross contractual obligation	35,000,000
CRO [Member] | Maximum [Member]
Commitments And Contingencies [Line Items]
Gross contractual obligation	40,000,000
CRO [Member] | Maximum [Member] | CRO Pass-through Expenses [Member]
Commitments And Contingencies [Line Items]
Gross contractual obligation	30,000,000
Intellectual Property Assets [Member]
Commitments And Contingencies [Line Items]
Other accrued liabilities current	500,000					1,100,000
Other long-term liabilities	$ 1,800,000					$ 2,200,000
Intellectual Property Assets [Member] | Embolitech LLC [Member]
Commitments And Contingencies [Line Items]
Contingency period ending year	2033
Payments to acquire intangible assets	$ 1,000,000.0
Intellectual Property Assets [Member] | Embolitech LLC [Member] | Forecast [Member]
Commitments And Contingencies [Line Items]
Contractual obligation payable in fiscal 2022 through fiscal 2024					$ 2,500,000
Intellectual Property Assets [Member] | InnoCore Technologies BV [Member]
Commitments And Contingencies [Line Items]
License agreement commencement year	2006
Annual minimum payments for licenses	$ 200,000
Patent expiry date	2027-05
Future minimum payments associated with license	$ 1,500,000
Intellectual Property Assets [Member] | Medical Device [Member]
Commitments And Contingencies [Line Items]
Payments to acquire in-process research and development	200,000		$ 800,000
Contingent payments upon achievement of regulatory milestones	$ 1,100,000
Contingency period ending year	2022