Summary of Significant Accounting Policies - Additional Information (Detail)		3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 03, 2013 $ / shares shares	Sep. 30, 2015 USD ($) $ / shares shares	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) $ / shares shares	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($) $ / shares shares	Mar. 31, 2014 $ / shares shares	Mar. 30, 2014 shares
Accounting Policies [Line Items]
Accumulated deficit		$ (169,285,000)		$ (169,285,000)		$ (135,916,000)
Net loss		$ (13,901,000)	$ (11,507,000)	$ (33,369,000)	$ (29,573,000)
Common stock, shares issued | shares		100,103,989		100,103,989		63,182,806	48,855,255	244,276,923
Common stock, shares outstanding | shares		100,102,816		100,102,816		63,182,806	48,855,255	244,276,923
Common stock, par value (in dollars per share) | $ / shares		$ 0.001		$ 0.001		$ 0.001	$ 0.001
Impairment charges				$ 0		$ 0
Debt issuance costs reclassified				$ 100,000
Maximum [Member]
Accounting Policies [Line Items]
Amortization period				10 years
Minimum [Member]
Accounting Policies [Line Items]
Amortization period				7 years
Safe Stitch Medical Inc [Member]
Accounting Policies [Line Items]
Exchange ratio	1.1533
Common stock, shares outstanding | shares	12,350,000
Common stock, par value (in dollars per share) | $ / shares	$ 0.001
Amortization period	5 years