Commitments and Contingencies - Additional Information (Detail)	1 Months Ended			3 Months Ended
	Apr. 30, 2017	Dec. 31, 2016 USD ($) ft²	Mar. 31, 2015 USD ($) ft²	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($) Patent	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	Feb. 28, 2019 ConvertibleNote	Dec. 09, 2016 Patent
Other Commitments [Line Items]
Standard product warranty, description				limited one- to five-year warranty
Retainer fees				$ 12,212,000	$ 14,135,000
Contingent consideration payment secured by convertible notes				8,500,000
Additional contingent consideration payment secured by convertible note				3,000,000.0
Secured convertible note, measured at amortized cost				8,000,000.0
Value of certain rights measured at cost				1,000,000.0
Contingent liabilities				0			$ 0
Patent Infringement [Member]
Other Commitments [Line Items]
Contingent liabilities				0
Boston Scientific Corporation [Member]
Other Commitments [Line Items]
Patent infringement lawsuit allegation against number of patents | Patent					8				10
First Obligation [Member]
Other Commitments [Line Items]
Number of additional secured convertible notes | ConvertibleNote								2
Licensing Agreements [Member]
Other Commitments [Line Items]
Annual royalty payment				$ 744,000	$ 657,000
Mayo And VGL [Member] | Licensing Agreements [Member]
Other Commitments [Line Items]
License agreement, terms				The agreement will terminate upon the expiration of (1) the last to expire of the licensed patents or (2) the Company’s obligations to pay royalties, whichever is later, unless terminated earlier. The agreement can be terminated by the Company, Mayo or VGL upon 60 days’ notice of a party’s material breach if such breach remains uncured after such 60-day period.
Mayo Foundation [Member] | Licensing Agreements [Member]
Other Commitments [Line Items]
Retainer fees				$ 40,000
Mayo Foundation [Member] | Licensing Agreements [Member] | Minimum [Member]
Other Commitments [Line Items]
Annual royalty payment				$ 200,000
Scenario Forecast [Member]
Other Commitments [Line Items]
Value of certain rights measured at cost						$ 1,000,000.0
Redwood Office Agreement [Member]
Other Commitments [Line Items]
Lease agreement, commencement period				2015-03
Area of office space | ft²			50,000
Lease agreement, effective date			Jun. 30, 2015
Lease agreement, expiration period			2022-05
Lease expense, payment due			$ 2,000,000.0
Annual lease expense payable in final year of lease term			$ 2,400,000
Redwood Office Agreement Additional Expansion Premises [Member] | Amendment 1 [Member]
Other Commitments [Line Items]
Area of office space | ft²		50,000
Lease expense, payment due		$ 1,200,000
Annual lease expense payable in final year of lease term		$ 2,900,000
Commencement date description				The lease for the Expansion Premises commenced on June 1, 2018
Lease commencement date		Jun. 01, 2018
Lease agreement, expiration date		May 31, 2025
Redwood Office Agreement Additional Expansion Premises [Member] | Amendment 2 [Member]
Other Commitments [Line Items]
Lease agreement, effective date	May 31, 2017
Lease agreement, expiration date	Jun. 01, 2018
Non-cancellable Facility Lease [Member]
Other Commitments [Line Items]
Lease agreement, effective date				Mar. 01, 2017
Lease agreement, expiration date				Feb. 28, 2022
Lease agreement, lease expense				$ 400,000