Commitments and Contingencies - Additional Information (Detail)	3 Months Ended		6 Months Ended		12 Months Ended	60 Months Ended
	Mar. 31, 2020 USD ($) € / $	Sep. 30, 2019 USD ($)	Mar. 31, 2020 USD ($) € / $	Mar. 31, 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	$ 7,442,000	$ 5,512,000	7,442,000
Embolitech LLC [Member]
Commitments And Contingencies [Line Items]
Contingent payments upon achievement of regulatory milestones			$ 2,000,000
Installment payment beginning period			2022	2022
Installment payment ending period			2024	2024
CRO [Member]
Commitments And Contingencies [Line Items]
Contractual obligation remaining to be paid	10,500,000		$ 10,500,000
CRO [Member] | Maximum [Member]
Commitments And Contingencies [Line Items]
Gross contractual obligation	40,000,000		40,000,000
CRO [Member] | Minimum [Member]
Commitments And Contingencies [Line Items]
Gross contractual obligation	35,000,000		35,000,000
CRO [Member] | CRO Pass-through Expenses [Member] | Maximum [Member]
Commitments And Contingencies [Line Items]
Gross contractual obligation	25,000,000		$ 25,000,000
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	2033
Additional payments for acquisition of in-process research and development	1,000,000
Payments upon initial acquisition of in-process research and development					$ 5,000,000
Contractual obligation payable in fiscal 2022 through fiscal 2024						$ 2,500,000
Other accrued liabilities noncurrent	100,000	1,000,000	$ 100,000
Other long-term liabilities	$ 2,200,000	$ 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			$ 220,000	€ 200,000
Exchange rate relating to license payment | € / $	1.0999		1.0999
Patent expiry date			2027-09	2027-09
Future minimum payments associated with license	$ 1,600,000		$ 1,600,000