| (Millions) | 2013 | 2012 | |||||
| Patents | $ | 602 | $ | 596 | |||
| Other amortizable intangible assets (primarily tradenames and customer related | |||||||
| intangibles) | 2,445 | 2,456 | |||||
| Total gross carrying amount | $ | 3,047 | $ | 3,052 | |||
| Accumulated amortization — patents | (458) | (421) | |||||
| Accumulated amortization — other | (1,030) | (833) | |||||
| Total accumulated amortization | $ | (1,488) | $ | (1,254) | |||
| Total finite-lived intangible assets — net | $ | 1,559 | $ | 1,798 | |||
| Non-amortizable intangible assets (primarily tradenames) | 129 | 127 | |||||
| Total intangible assets — net | $ | 1,688 | $ | 1,925 | |||