Commitments and Contingencies - Additional Information (Detail)	3 Months Ended		6 Months Ended	9 Months Ended		12 Months Ended	60 Months Ended
	Mar. 31, 2020 USD ($)	Sep. 30, 2019 USD ($)	Mar. 31, 2020 USD ($)	Jun. 30, 2020 USD ($) € / $	Jun. 30, 2020 EUR (€)	Sep. 30, 2018 USD ($)	Sep. 30, 2024 USD ($)
Commitments And Contingencies [Line Items]
Additional payments for acquisition of in-process research and development				$ 1,000,000
Other long-term liabilities		$ 5,512,000		7,865,000
Embolitech LLC [Member]
Commitments And Contingencies [Line Items]
Contingent payments upon achievement of regulatory milestones			$ 2,000,000.0
Installment payment beginning period			2022
Installment payment ending period			2024
CRO [Member]
Commitments And Contingencies [Line Items]
Contractual obligation remaining to be paid				10,000,000
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] | CRO Pass-through Expenses [Member]
Commitments And Contingencies [Line Items]
Gross contractual obligation				26,000,000
Intellectual Property [Member] | Medical Device [Member]
Commitments And Contingencies [Line Items]
Payments to acquire intellectual property assets		800,000
Contingent payments upon achievement of regulatory milestones		$ 1,300,000
Contingency period ending year		2022
Estimated additional payment to acquire intellectual property assets		$ 200,000
Intellectual Property [Member] | Embolitech LLC [Member]
Commitments And Contingencies [Line Items]
Contingency period ending year			2033
Additional payments for acquisition of in-process research and development	$ 1,000,000.0
Payments upon initial acquisition of in-process research and development						$ 5,000,000.0
Contractual obligation payable in fiscal 2022 through fiscal 2024							$ 2,500,000
Other accrued liabilities noncurrent		1,000,000.0		100,000
Other long-term liabilities		$ 2,100,000		$ 2,200,000
Intellectual Property [Member] | InnoCore Technologies BV [Member]
Commitments And Contingencies [Line Items]
License agreement commencement year				2006	2006
Annual minimum payments for licenses				$ 225,000	€ 200,000
Exchange rate relating to license payment | € / $				1.1228
Patent expiry date				2027-09	2027-09
Future minimum payments associated with license				$ 1,700,000