Commitments and contingencies - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Commitments and Contingencies [Line Items]
Rent expense	$ 650,000	$ 650,000
Remediation costs	100,000	102,000
Officers compensation	288,500
Insurance Policy Amount	$ 1,000,000