| Restricted Stock and Restricted Stock Units | ||||||||||||||||||
| The following table summarizes restricted stock and restricted stock unit activity for the years ended December 31: | ||||||||||||||||||
| 2013 | 2012 | 2011 | ||||||||||||||||
| Weighted Average | Weighted Average | Weighted Average | ||||||||||||||||
| Number of | Grant Date | Number of | Grant Date | Number of | Grant Date | |||||||||||||
| Awards | Fair Value | Awards | Fair Value | Awards | Fair Value | |||||||||||||
| Nonvested balance — | ||||||||||||||||||
| As of January 1 | 3,261,562 | $ | 85.17 | 4,858,972 | $ | 73.02 | 4,812,657 | $ | 68.75 | |||||||||
| Granted | ||||||||||||||||||
| Annual | 946,774 | 101.57 | 968,522 | 87.92 | 889,448 | 89.46 | ||||||||||||
| Other | 44,401 | 111.19 | 99,337 | 85.07 | 351,624 | 87.07 | ||||||||||||
| Vested | (1,100,095) | 79.93 | (2,594,468) | 63.51 | (1,077,816) | 72.21 | ||||||||||||
| Forfeited | (47,281) | 90.82 | (70,801) | 82.65 | (116,941) | 72.01 | ||||||||||||
| As of December 31 | 3,105,361 | $ | 92.31 | 3,261,562 | $ | 85.17 | 4,858,972 | $ | 73.02 | |||||||||