Commitments and Contingencies - Additional Information (Detail)	1 Months Ended		3 Months Ended		12 Months Ended				49 Months Ended
	Jul. 31, 2019 USD ($)	Nov. 30, 2017 USD ($) ft²	Sep. 30, 2019 USD ($) ft² € / $	Jun. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) ft² € / $ shares	Sep. 30, 2019 EUR (€) shares	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Dec. 31, 2023 USD ($)
Commitments And Contingencies [Line Items]
Settlement of claim					$ 400,000
Additional shares of common stock to stockholders | shares					480,059	480,059
License agreement commencement date					2006-03	2006-03
Exchange rate relating to license payment | € / $			1.0916		1.0916
Future minimum payments associated with license			$ 1,700,000		$ 1,700,000
Rent expense related to operating leases					500,000		$ 500,000	$ 100,000
Acquisition charge for in-process of research and development					890,000		7,888,000
Other long-term liabilities			$ 5,512,000		$ 5,512,000		5,720,000
Eden Prairie Minnesota [Member]
Commitments And Contingencies [Line Items]
Square feet of office and R&D facility | ft²		36,000	13,000		13,000
Contractual obligations		$ 5,200,000
Operating lease agreement term		10 years
Operating lease agreement commencement date		2018-05
CRO [Member]
Commitments And Contingencies [Line Items]
Contractual obligation to be paid			$ 11,800,000		$ 11,800,000
Embolitech LLC [Member]
Commitments And Contingencies [Line Items]
Contingent payments upon achievement of regulatory milestones					$ 2,000,000
Installment payment beginning period					2020-01	2020-01
Installment payment ending period					2023-12	2023-12
Minimum [Member] | CRO [Member]
Commitments And Contingencies [Line Items]
Contractual obligation due in next several years			35,000,000		$ 35,000,000
Maximum [Member] | CRO [Member]
Commitments And Contingencies [Line Items]
Contractual obligations			26,000,000		26,000,000
Contractual obligation due in next several years			40,000,000		40,000,000
License [Member]
Commitments And Contingencies [Line Items]
Annual minimum payments for licenses					$ 218,000	€ 200,000
Patents [Member]
Commitments And Contingencies [Line Items]
Patent expiry date					2027-09	2027-09
Intellectual Property [Member]
Commitments And Contingencies [Line Items]
Payments to acquire intellectual property assets			900,000
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	2022
Estimated additional payment to acquire intellectual property assets	$ 200,000
Acquisition charge for in-process of research and development			900,000
Intellectual Property [Member] | Embolitech LLC [Member]
Commitments And Contingencies [Line Items]
Payments to acquire intellectual property assets				$ 7,900,000	$ 5,000,000
Contingency period ending year					2033	2033
Acquisition charge for in-process of research and development							7,900,000
Other accrued liabilities noncurrent			1,000,000		$ 1,000,000
Other long-term liabilities			$ 2,100,000		2,100,000
Intellectual Property [Member] | Embolitech LLC [Member] | Scenario Forecast [Member]
Commitments And Contingencies [Line Items]
Estimated additional payment to acquire intellectual property assets									$ 3,500,000
Selling, general and administrative [Member]
Commitments And Contingencies [Line Items]
Claim accrual recorded in selling, general and other administrative expenses							1,000,000
Reduction in selling, general and administrative expenses					$ 600,000
Other Accrued Liabilities [Member]
Commitments And Contingencies [Line Items]
Claim accrual recorded in other accrued liabilities							$ 1,000,000