The following table shows authorized shares and provides a reconciliation of common shares issued and outstanding for the years ended December 31:
| (Millions, except where indicated) | 2013 | 2012 | 2011 | ||||
| Common shares authorized (billions)(a) | 3.6 | 3.6 | 3.6 | ||||
| Shares issued and outstanding at beginning | |||||||
| of year | 1,105 | 1,164 | 1,197 | ||||
| Repurchases of common shares | (55) | (69) | (48) | ||||
| Other, primarily stock option exercises | |||||||
| and restricted stock awards granted | 14 | 10 | 15 | ||||
| Shares issued and outstanding as of | |||||||
| December 31 | 1,064 | 1,105 | 1,164 | ||||