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Investments (Tables) | 3 Months Ended
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Mar. 31, 2017
Investments, Debt and Equity Securities [Abstract] |
Schedule of Investments | The following table presents the details of our investments:
| March 31, 2017 |  | December 31, 2016
| (in millions)
Trading securities | $ | 203 |  |  | $ | 228 |
Available-for-sale investment securities | 17 |  |  | 17 |
Equity method investments | 128 |  |  | 124 |
Cost method investments | 145 |  |  | 144 |

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