Commitments and Contingencies - Additional Information (Detail)	1 Months Ended	3 Months Ended			12 Months Ended	49 Months Ended
	Nov. 30, 2017 USD ($) ft²	Dec. 31, 2018 USD ($) € / $	Dec. 31, 2018 EUR (€)	Dec. 31, 2017 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2023 USD ($)
Commitments And Contingencies [Line Items]
License agreement commencement date		2006-03	2006-03
Annual minimum payments for licenses		$ 229,000	€ 200,000
Exchange rate relating to license payment | € / $		1.1444
Future minimum payments associated with license		$ 2,100,000
Rent expense related to operating leases		100,000		$ 100,000
Other long-term liabilities		$ 5,712,000			$ 5,720,000
Eden Prairie Minnesota [Member]
Commitments And Contingencies [Line Items]
Square feet facility | ft²	36,000
Operating lease agreement term	10 years
Operating lease agreement commencement date	2018-05
Amount deposited into restricted cash account	$ 400,000
Patents [Member]
Commitments And Contingencies [Line Items]
Patent expiry date		2027-09	2027-09
Intellectual Property [Member] | Embolitech LLC [Member]
Commitments And Contingencies [Line Items]
Payments to acquire intellectual property assets		$ 5,000,000
Installment payment beginning period		2019-12	2019-12
Installment payment ending period		2023-12	2023-12
Contingent payments upon achievement of regulatory milestones		$ 2,000,000
Contingency period ending year		2033	2033
Other long-term liabilities		$ 3,000,000			2,900,000
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
Other Accrued Liabilities [Member]
Commitments And Contingencies [Line Items]
Claim accrual recorded in other accrued liabilities		$ 1,000,000			$ 1,000,000