Issue of options under equity incentive plan - Narrative (Detail) (USD $)	3 Months Ended		6 Months Ended		55 Months Ended	1 Months Ended	6 Months Ended	1 Months Ended	6 Months Ended
	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2013	Dec. 31, 2010 Options Granted December 13, 2010 2010 Equity Incentive Plan	Apr. 30, 2013 Options Granted December 13, 2010 2010 Equity Incentive Plan	May 31, 2011 Options Granted May 2011 2010 Equity Incentive Plan	Apr. 30, 2013 Options Granted May 2011 2010 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted						2,500,000		750,000
Employee stock option vesting rights							1/3 on December 13, 2010, 1/3 vested on November 17, 2011 and the balance vested on November 17, 2012.		1/3 upon grant date, 1/3 vested on February 1, 2012 and the balance vested on February 1, 2013.
Stock options expiration date							Nov. 17, 2020		Feb. 01, 2018
Weighted average grant date fair value per option granted							$ 0.81		$ 0.99
Weighted average remaining contractual life							7 years 6 months		4 years 9 months
Options exercisable							2,500,000		750,000
Stock based compensation	$ 384	$ 120,714	$ 76,538	$ 401,919	$ 2,729,167		$ 40,686		$ 35,852