| Shares (in millions) | Weighted Average Exercise Price | Weighted Average Remaining Contractual Term (in years) | Aggregate Intrinsic Value (a) (in millions) | |||||||||||
| Outstanding at December 31, 2012 | 15.3 | 49.07 | ||||||||||||
| Granted | 1.9 | 74.29 | ||||||||||||
| Exercised | (5.1) | 44.79 | ||||||||||||
| Canceled / Expired | (0.6) | 56.38 | ||||||||||||
| Outstanding at December 31, 2013 | 11.5 | 54.81 | 4.1 | |||||||||||
| Vested and Unvested Expected to Vest at | ||||||||||||||
| December 31, 2013 | 11.1 | 54.47 | 4.1 | $ | 629.6 | |||||||||
| Exercisable at December 31, 2013 | 5.4 | 48.49 | 3.1 | $ | 336.8 | |||||||||