| General Employees' Stock Purchase Plan | ||||||||||||||||||
| 2013 | 2012 | 2011 | ||||||||||||||||
| Weighted | Weighted | Weighted | ||||||||||||||||
| Average | Average | Average | ||||||||||||||||
| Shares | Exercise Price | Shares | Exercise Price | Shares | Exercise Price | |||||||||||||
| Options granted | 1,259,247 | $ | 93.46 | 1,455,545 | $ | 75.32 | 1,433,609 | $ | 73.67 | |||||||||
| Options exercised | (1,259,247) | 93.46 | (1,455,545) | 75.32 | (1,433,609) | 73.67 | ||||||||||||
| Shares available for grant - | ||||||||||||||||||
| December 31 | 30,185,960 | 31,445,207 | 2,900,751 | |||||||||||||||