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Asset Acquisition and License Agreements - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended			3 Months Ended		9 Months Ended
	Jun. 30, 2017	Dec. 31, 2016	Aug. 31, 2004	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Asset Acquisition [Line Items]
Restricted cash (SRX Cardio)		$ 178		$ 170		$ 170
Net income (loss) attributable to Non Controlling interest (SRX Cardio)				(5)	$ 1,853	190	$ 1,853
Milestone payment on regulatory approval						5,000
Millennium
Asset Acquisition [Line Items]
Notice period for agreement termination			30 days
Millennium \| United States
Asset Acquisition [Line Items]
Milestone payment on regulatory approval	$ 5,000
Additional milestone payable for other indications approved				23,000		23,000
Millennium \| Europe
Asset Acquisition [Line Items]
Milestone payable for approval event				5,000		5,000
Additional milestone payable for other indications approved				23,000		23,000
Millennium \| Research and Development Expense
Asset Acquisition [Line Items]
Milestone payment		$ 2,000
Millennium \| Cost of Sales \| United States
Asset Acquisition [Line Items]
Finite-lived intangible assets, amortization expenses				200		$ 200
SRX Cardio
Asset Acquisition [Line Items]
Variable interest entity, Terms of arrangements						Accordingly, we have consolidated the financial statements of SRX Cardio since inception of the agreement on December 1, 2015 by (a) eliminating all intercompany balances and transactions; and (b) allocating loss (income) attributable to the noncontrolling interest in SRX Cardio to net loss attributable to noncontrolling interest in our consolidated statement of operations and reflecting noncontrolling interest on our consolidated balance sheet.
Restricted cash (SRX Cardio)				$ 200		$ 200