| ($ in millions) | |||||||||||
| 2013 | 2012 | 2011 | |||||||||
| Balance at January 1 | $ | 5,672 | $ | 5,575 | $ | 5,293 | |||||
| Additions based on tax positions related to the current year | 829 | 401 | 672 | ||||||||
| Additions for tax positions of prior years | 417 | 215 | 379 | ||||||||
| Reductions for tax positions of prior years (including | |||||||||||
| impacts due to a lapse in statute) | (2,201) | (425) | (538) | ||||||||
| Settlements | (259) | (94) | (231) | ||||||||
| Balance at December 31 | $ | 4,458 | $ | 5,672 | $ | 5,575 | |||||