|
Stock Compensation Plans (Details 5) (USD $)
In Millions, except Share data, unless otherwise specified |
12 Months Ended | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Dec. 31, 2011
|
Dec. 31, 2010
|
Dec. 31, 2009
|
Dec. 31, 2011
United States
M
|
Dec. 31, 2010
United States
M
|
Dec. 31, 2009
United States
|
Dec. 31, 2008
United States
|
Dec. 31, 2011
United States
Maximum
|
Dec. 31, 2011
United Kingdom
Y
|
Dec. 31, 2010
United Kingdom
|
Dec. 31, 2009
United Kingdom
|
Dec. 31, 2008
United Kingdom
Maximum
|
Dec. 31, 2006
United Kingdom
Maximum
|
|
| Share-based Compensation Arrangement by Share-based Payment Award | |||||||||||||
| Maximum purchase of shares under plan (in shares) | 7,500,000 | 200,000 | 525,000 | ||||||||||
| Period of interval for purchase of common stock (in months) | 6 | 3 | |||||||||||
| Purchase price expressed as a percentage of the fair market value of common stock (as a percent) | 85.00% | 85.00% | |||||||||||
| Stock issued to employees under the plan (in shares) | 468,000 | 357,000 | 323,000 | 320,000 | 63,000 | 5,000 | 201,000 | ||||||
| Compensation expense | $ 235 | $ 221 | $ 209 | $ 5 | $ 3 | $ 3 | $ 1 | $ 1 | $ 1 | ||||
| Waiting period before purchase of shares (in years) | 3 | ||||||||||||