Financial instruments - Fair Value of Significant Unobservable Inputs (Detail) (Significant Un-Observable Inputs (Level 3) [Member], USD $)	3 Months Ended	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2014
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 107,597	$ 1,021,526
Change in fair value of derivative liabilities	(14,501)	(128,224)
Derecognition of liabilities upon preferred stock conversion to common stock conversion		(800,206)
Ending balance	93,096	93,096
Embedded Derivative Liabilities [Member] | Preferred Stock [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance		800,206
Change in fair value of derivative liabilities
Derecognition of liabilities upon preferred stock conversion to common stock conversion		(800,206)
Ending balance
Bank Loan [Member] | Derivative [Member] | Common Stock Warrants [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	107,597	221,320
Change in fair value of derivative liabilities	(14,501)	(128,224)
Derecognition of liabilities upon preferred stock conversion to common stock conversion
Ending balance	$ 93,096	$ 93,096