| **Indebtedness - (Tables)**                                           | 6 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
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| **Debt Disclosure [Abstract]**                                        |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
| Schedule of Debt - Net of Unamortized Discount and Debt Issuance Cost | Total debt consisted of the following at June 30, 2016, net of unamortized discount and debt issuance cost: June 30,   2016 December 31, 20156.0% Notes due June 2018$200 $2557.5% Senior Notes due November 2018524 7473.2% Senior Notes due August 2021511 7468.55% Debentures due June 2024112 1496.875% Notes due January 2029302 3945.125% Notes due September 20401,132 1,482Other debt245 268Total debt3,026 4,041Less:  short-term debt and current portion of long-term debt139 151Total long-term debt$2,887 $3,890 |

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| - Definition
Tabular disclosure of information pertaining to short-term and long-debt instruments or arrangements, including but not limited to identification of terms, features, collateral requirements and other information necessary to a fair presentation.
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