The Company - Additional Information (Detail)				1 Months Ended	3 Months Ended	6 Months Ended		20 Months Ended
	Nov. 06, 2015 USD ($)	Nov. 03, 2014 USD ($)	Sep. 30, 2014 USD ($)	Oct. 31, 2013 USD ($) $ / shares shares	Jun. 30, 2016 USD ($) shares	Jun. 30, 2016 USD ($) Segment shares	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) shares
Organization And Nature Of Business [Line Items]
Number of operating segments | Segment						1
Common stock initial public offering (in shares) | shares				7,728,000
Net proceeds from initial public offering				$ 68,300,000
Proceeds from sale of common stock						$ 2,043,000	$ 35,426,000
Sale of stock, commissions, percentage of gross sales (up to)					3.00%	3.00%		3.00%
Convertible notes
Organization And Nature Of Business [Line Items]
Gross proceeds			$ 125,000,000
Proceeds from issuance of convertible notes, net of discounts			$ 122,900,000
IPO
Organization And Nature Of Business [Line Items]
Public offering price of the shares sold (in USD per share) | $ / shares				$ 10.00
Maximum
Organization And Nature Of Business [Line Items]
Shelf registration statement, aggregate dollar amount	$ 150,000,000.0	$ 150,000,000.0
Common stock
Organization And Nature Of Business [Line Items]
Shelf registration, amount available for issuance					$ 46,100,000	$ 46,100,000		$ 46,100,000
Cantor Fitzgerald and Co. | Common stock
Organization And Nature Of Business [Line Items]
Common stock issued and sold under sales agreement (in shares) | shares					111,403	111,403		1,865,959
Proceeds from sale of common stock					$ 2,000,000	$ 2,000,000		$ 52,500,000
Cantor Fitzgerald and Co. | Common stock | Maximum
Organization And Nature Of Business [Line Items]
Shelf registration statement, aggregate dollar amount	$ 50,000,000.0	$ 50,000,000