Note 12. Goodwill and Other Intangible Assets - Net
The change in the carrying amount of goodwill for the years ended December 31, 2013 and 2012 by segment is as follows:
| Currency | ||||||||
| December 31, | Translation | December 31, | ||||||
| 2012 | Acquisitions | Adjustment | 2013 | |||||
| Aerospace | $ | 2,075 | $ | - | $ | 1 | $ | 2,076 |
| Automation and Control | ||||||||
| Solutions | 8,343 | 606 | - | 8,949 | ||||
| Performance Materials | ||||||||
| and Technologies | 1,810 | 12 | 2 | 1,824 | ||||
| Transportation Systems | 197 | - | - | 197 | ||||
| $ | 12,425 | $ | 618 | $ | 3 | $ | 13,046 |
We completed our annual impairment testing of goodwill and indefinite-lived intangibles as of March 31, 2013 and determined that there was no impairment as of that date. No matters have arisen subsequent to that date which have resulted in a change to this assessment.
| December 31, 2013 | December 31, 2012 | ||||||||||||
| Gross | Net | Gross | Net | ||||||||||
| Carrying | Accumulated | Carrying | Carrying | Accumulated | Carrying | ||||||||
| Amount | Amortization | Amount | Amount | Amortization | Amount | ||||||||
| Determinable life intangibles: | |||||||||||||
| Patents and technology | $ | 1,438 | $ | (935) | $ | 503 | $ | 1,224 | $ | (841) | $ | 383 | |
| Customer relationships | 1,904 | (749) | 1,155 | 1,736 | (625) | 1,111 | |||||||
| Trademarks | 194 | (118) | 76 | 179 | (103) | 76 | |||||||
| Other | 294 | (234) | 60 | 311 | (157) | 154 | |||||||
| 3,830 | (2,036) | 1,794 | 3,450 | (1,726) | 1,724 | ||||||||
| Indefinite life intangibles: | |||||||||||||
| Trademarks | 720 | - | 720 | 725 | - | 725 | |||||||
| $ | 4,550 | $ | (2,036) | $ | 2,514 | $ | 4,175 | $ | (1,726) | $ | 2,449 | ||
Intangible assets amortization expense was $319 million, $266 million, and $249 million in 2013, 2012, 2011, respectively. Estimated intangible asset amortization expense for each of the next five years approximates $261 million in 2014, $217 million in 2015, $193 million in 2016, $183 million in 2017, and $168 million in 2018.