Commitments and contingencies - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended		5 Months Ended	0 Months Ended			6 Months Ended	12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2014 Subsequent Event [Member]	Oct. 22, 2013 Dr. Kornman [Member]	Oct. 22, 2013 Mr. Lurier [Member]	Oct. 22, 2013 Scott Snyder [Member]	Jun. 30, 2014 Scott Snyder [Member]	Dec. 31, 2013 Scott Snyder [Member]	Jan. 02, 2013 Scott Snyder [Member]	Jan. 02, 2013 Installment One [Member] Scott Snyder [Member]	Jan. 02, 2013 Installment Two [Member] Scott Snyder [Member]	Jan. 02, 2013 Installment Three [Member] Scott Snyder [Member]
Loss Contingencies [Line Items]
Executive bonus to base salary percentage											30.00%
Granted,share						2,250,000	750,000	675,000	200,000
Granted,weighted avg.exercise price			$ 0.35	$ 0.29		$ 0.3799	$ 0.3799	$ 0.3799	$ 0.29
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Number												50,000	66,000	84,000
Basic Salary											$ 265,000
Reimbursement expenditure maximum										34,000
Additional reimbursement expenditure			16,000		20,000
Operating Leases, Rent Expense	$ 79,000	$ 81,000	$ 150,000	$ 161,000
Property Under Commercial Lease And Sublease Details			On February 7, 2014, the Company entered into the Second Amendment to Commercial Lease which, among other things, extends the term of the lease from March 31, 2014 to March 31, 2017 and reduced the 19,000 square feet, the amount of space under the master lease, by approximately 6,011 square feet, to approximately 13,000 square feet, the current space the Company occupies. In May 2010, the Company completed a sublease of the 6,011 square feet of underutilized office and laboratory space.