| **Effects on net income of amounts reclassified from accumulated other comprehensive income (loss) (Details) - USD ($) $ in Millions** | 3 Months Ended | 6 Months Ended |
|----------------------------------------------------------------------------------------------------------------------------------------|----------------|----------------|
||
| **Accumulated Other Comprehensive Income (Loss) [Line Items]**                                                                         |           |           |   |   |
| Amounts reclassified from accumulated other comprehensive income (loss)                                                                | $ (5)          | $ (5)          | $ (11) | $ (8) |
| Unrealized Gains (Losses) on Available-for-Sale Securities [Member]                                                                    |           |           |   |   |
| **Accumulated Other Comprehensive Income (Loss) [Line Items]**                                                                         |           |           |   |   |
| Amounts reclassified from accumulated other comprehensive income (loss)                                                                | (1)            | (1)            | (1) | (1) |
| Unrealized Gains (Losses) on Available-for-Sale Securities [Member] | Interest Income [Member]                                         |           |           |   |   |
| **Accumulated Other Comprehensive Income (Loss) [Line Items]**                                                                         |           |           |   |   |
| Amounts reclassified from accumulated other comprehensive income (loss)                                                                | (1)            | (1)            | (1) | (1) |
| Unrealized Gains (Losses) on Derivative Instruments [Member]                                                                           |           |           |   |   |
| **Accumulated Other Comprehensive Income (Loss) [Line Items]**                                                                         |           |           |   |   |
| Amounts reclassified from accumulated other comprehensive income (loss)                                                                | (4)            | (4)            | (10) | (7) |
| Unrealized Gains (Losses) on Derivative Instruments [Member] | Sales Revenue, Net                                                      |           |           |   |   |
| **Accumulated Other Comprehensive Income (Loss) [Line Items]**                                                                         |           |           |   |   |
| Amounts reclassified from accumulated other comprehensive income (loss)                                                                | (4)            | (6)            | (9) | (14) |
| Unrealized Gains (Losses) on Derivative Instruments [Member] | Research And Development [Member]                                       |           |           |   |   |
| **Accumulated Other Comprehensive Income (Loss) [Line Items]**                                                                         |           |           |   |   |
| Amounts reclassified from accumulated other comprehensive income (loss)                                                                | $ 0            | $ 2            | $ (1) | $ 7 |

| 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
Amount after tax of reclassification adjustments of other comprehensive income (loss).
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -URI http://asc.fasb.org/extlink&oid=66004124&loc=SL7669686-108580Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 55 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=66004921&loc=d3e1436-108581
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