Unrecognized tax benefits | ||||||||||||
Year ended December 31, (in millions) | 2013 | 2012 | 2011 | |||||||||
Balance at January 1, | $ | 7,158 | $ | 7,189 | $ | 7,767 | ||||||
Increases based on tax positions related to the current period | 542 | 680 | 516 | |||||||||
Decreases based on tax positions related to the current period | — | — | (110 | ) | ||||||||
Increases based on tax positions related to prior periods | 88 | 234 | 496 | |||||||||
Decreases based on tax positions related to prior periods | (2,200 | ) | (853 | ) | (1,433 | ) | ||||||
Decreases related to settlements with taxing authorities | (53 | ) | (50 | ) | (16 | ) | ||||||
Decreases related to a lapse of applicable statute of limitations | — | (42 | ) | (31 | ) | |||||||
Balance at December 31, | $ | 5,535 | $ | 7,158 | $ | 7,189 | ||||||