The following is a summary of other assets as of December 31:
(Millions) | 2013 | 2012 | ||||
Goodwill | $ | 3,198 | $ | 3,181 | ||
Deferred tax assets, net(a) | 2,443 | 2,458 | ||||
Prepaid expenses(b) | 1,998 | 1,960 | ||||
Other intangible assets, at amortized cost | 817 | 993 | ||||
Restricted cash(c) | 486 | 568 | ||||
Derivative assets(a) | 329 | 593 | ||||
Other | 1,957 | 1,665 | ||||
Total | $ | 11,228 | $ | 11,418 |
The components of other intangible assets were as follows:
2013 | 2012 | |||||||||||||||||
(Millions) | Gross Carrying Amount | Accumulated Amortization | Net Carrying Amount | Gross Carrying Amount | Accumulated Amortization | Net Carrying Amount | ||||||||||||
Customer relationships(a) | $ | 1,297 | $ | (660) | $ | 637 | $ | 1,238 | $ | (526) | $ | 712 | ||||||
Other | 269 | (89) | 180 | 428 | (147) | 281 | ||||||||||||
Total | $ | 1,566 | $ | (749) | $ | 817 | $ | 1,666 | $ | (673) | $ | 993 |
The changes in the carrying amount of goodwill reported in the Company's reportable operating segments and Corporate & Other were as follows:
Corporate & | ||||||||||||||||||
(Millions) | USCS | ICS | GCS | GNMS | Other | Total | ||||||||||||
Balance as of January 1, 2012 | $ | 175 | $ | 1,023 | $ | 1,543 | $ | 160 | $ | 271 | $ | 3,172 | ||||||
Acquisitions | ― | 1 | ― | ― | ― | 1 | ||||||||||||
Dispositions | ― | (2) | (1) | ― | ― | (3) | ||||||||||||
Other, including foreign currency translation | ― | 9 | 2 | ― | ― | 11 | ||||||||||||
Balance as of December 31, 2012 | $ | 175 | $ | 1,031 | $ | 1,544 | $ | 160 | $ | 271 | $ | 3,181 | ||||||
Acquisitions | ― | ― | ― | ― | ― | ― | ||||||||||||
Dispositions | ― | ― | ― | ― | ― | ― | ||||||||||||
Other, including foreign currency translation | (1) | 21 | (1) | ― | (2) | 17 | ||||||||||||
Balance as of December 31, 2013 | $ | 174 | $ | 1,052 | $ | 1,543 | $ | 160 | $ | 269 | $ | 3,198 |
Estimated amortization expense for other intangible assets over the next five years is as follows:
(Millions) | 2014 | 2015 | 2016 | 2017 | 2018 | ||||||||||
Estimated amortization expense | $ | 184 | $ | 164 | $ | 123 | $ | 72 | $ | 61 |