|
Financing arrangements Financing arrangements (Details 1) (USD $)
In Millions, unless otherwise specified |
Dec. 31, 2012
|
Dec. 31, 2011
|
Dec. 31, 2010
|
|---|---|---|---|
| Schedule of 2013 convertible notes [Abstract] | |||
| Principal balance | $ 5,000 | $ 10,500 | $ 2,500 |
|
0.375% convertible notes due 2013 (0.375% 2013 Convertible Notes) [Member]
|
|||
| Schedule of 2013 convertible notes [Abstract] | |||
| Principal balance | 2,500 | ||
| Net carrying amount | 2,488 | ||
| Net carrying amount | 2,346 | ||
|
0.375% convertible notes due 2013 (0.375% 2013 Convertible Notes) [Member] | Liability Component [Member]
|
|||
| Schedule of 2013 convertible notes [Abstract] | |||
| Principal balance | 2,500 | 2,500 | |
| Unamortized discount | 12 | 154 | |
| Net carrying amount | 2,488 | ||
| Net carrying amount | 2,346 | ||
|
0.375% convertible notes due 2013 (0.375% 2013 Convertible Notes) [Member] | Equity Component [Member]
|
|||
| Schedule of 2013 convertible notes [Abstract] | |||
| Net carrying amount | $ 829 | $ 829 |