| Years ended November 30, | ||||||||||||||||||||||||
| 2013 | 2012 | 2011 | ||||||||||||||||||||||
| Number of warrants (thousands) | Weighted average exercise price | Number of warrants (thousands) | Weighted average exercise price | Number of warrants (thousands) | Weighted average exercise price | |||||||||||||||||||
| Balance – beginning of year | 36,529 | $ | 1.48 | 40,420 | $ | 1.49 | 49,345 | $ | 1.65 | |||||||||||||||
| Exercised | (36,529 | ) | $ | 1.48 | (3,891 | ) | $ | 1.48 | (8,925 | ) | $ | 1.48 | ||||||||||||
| Balance – end of year | — | — | 36,529 | $ | 1.48 | 40,420 | $ | 1.49 | ||||||||||||||||