| **Short-Term Borrowings (Details) - USD ($) $ in Millions** | Dec. 31, 2015 | Dec. 31, 2014 |
|-------------------------------------------------------------|---------------|---------------|
| **Short-term Debt**                                         |          |          |
| Short-term borrowings, Balance                              | $ 6,958       | $ 4,699       |
| Commercial paper, net                                       |          |          |
| **Short-term Debt**                                         |          |          |
| Short-term borrowings, Balance                              | $ 5,811       | $ 3,688       |
| Short-term borrowings, Avg. Rate                            | 0.50%         | 0.30%         |
| Bank borrowings                                             |          |          |
| **Short-term Debt**                                         |          |          |
| Short-term borrowings, Balance                              | $ 440         | $ 411         |
| Short-term borrowings, Avg. Rate                            | 9.30%         | 6.80%         |
| Variable denomination floating rate demand notes            |          |          |
| **Short-term Debt**                                         |          |          |
| Short-term borrowings, Balance                              | $ 707         | $ 600         |
| Short-term borrowings, Avg. Rate                            | 0.80%         | 0.80%         |

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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.13) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(a)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.(a),16(a)(1)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 13 -Subparagraph 2, 3 -Article 9
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| X                                                                                                                                                                                                                                                                                                                                                                                                              |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Weighted average interest rate of short-term debt outstanding.
+ References
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| X                                                                                                                                            |
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