Business Combination - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Aug. 31, 2015	Dec. 31, 2015	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill		$ 3,631	$ 3,631
Common Stock
Business Acquisition [Line Items]
Number of shares issued as consideration for acquisition		1,293,058
Cardiogen Sciences, Inc
Business Acquisition [Line Items]
Amount obligated to pay in common stock	$ 4,142
Amount obligated to pay in either cash or common stock	5,800
Aggregate contingent consideration	10,000
Goodwill	3,631
Consideration paid to the fair values of assets acquired and liabilities assumed	8,289
Cardiogen Sciences, Inc | Intellectual Property
Business Acquisition [Line Items]
Fair value of intellectual property	$ 8,000
Cardiogen Sciences, Inc | General and Administrative Expenses
Business Acquisition [Line Items]
Business acquisition costs, legal and accounting expenses		$ 400
Cardiogen Sciences, Inc | Common Stock
Business Acquisition [Line Items]
Number of shares issued as consideration for acquisition	1,293,058
Number of held back shares to cover potential indemnification requirements	133,986
Cardiogen Sciences, Inc | Series B Preferred Stock
Business Acquisition [Line Items]
Number of shares issued as consideration for acquisition	46,969