Amount of cash and cash equivalents restricted as to withdrawal or usage, classified as current. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Name:	us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Asset Acquisition and License Agreements - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended
	Dec. 31, 2015	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Asset Acquisition [Line Items]
Restricted cash (SRX Cardio)		$ 1,528,000		$ 1,062,000
Net Income (loss) attributable to noncontrolling interest (SRX Cardio)		$ 60,000	$ (332,000)
SRX Cardio
Asset Acquisition [Line Items]
Variable interest entity, Upfront payment	$ 500,000
Variable interest entity, Terms of arrangements		Accordingly, SRX Cardio is subject to consolidation and we have consolidated the financial statements of SRX Cardio.
Restricted cash (SRX Cardio)		$ 29,000		$ 30,000