Organization and Basis of Presentation - Additional Information (Detail) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Date of incorporation									Jan. 29, 2007
Net loss	$ (2,919,803)	$ (3,825,354)	$ (3,547,040)	$ (2,955,484)	$ (1,616,698)	$ (485,904)	$ (239,871)	$ (493,992)	$ (13,247,681)	$ (2,836,465)
Accumulated deficit	(35,939,149)				(22,691,468)				(35,939,149)	(22,691,468)
Cash and cash equivalents	14,155,809				24,196,691				14,155,809	24,196,691	116,013
Reverse stock split of issued and outstanding shares										One-for-five
Reverse stock split effective date									Aug. 30, 2013
Reverse stock split approved date									Aug. 29, 2013
Square 1 Bank [Member] | Loan and security agreement [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Borrowings under bank credit facility	$ 4,500,000								$ 4,500,000