Asset Acquisition and License Agreements - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended			3 Months Ended	6 Months Ended
	Jun. 30, 2017	Dec. 31, 2016	Aug. 31, 2004	Jun. 30, 2017	Jun. 30, 2017
Asset Acquisition [Line Items]
Restricted cash (SRX Cardio)	$ 172	$ 178		$ 172	$ 172
Net income attributable to Non Controlling interest (SRX Cardio)				240	195
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	23,000
Millennium | Europe
Asset Acquisition [Line Items]
Milestone payable for approval event	5,000			5,000	5,000
Additional milestone payable for other indications approved	23,000			23,000	$ 23,000
Millennium | Research and Development Expense
Asset Acquisition [Line Items]
Milestone payment		$ 2,000
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 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	$ 200