|
Consolidated Statements of Income (Parenthetical) (USD $)
In Millions, unless otherwise specified |
3 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
|
Dec. 31, 2014
|
Sep. 30, 2014
|
Jun. 30, 2014
|
Mar. 31, 2014
|
Dec. 31, 2013
|
Sep. 30, 2013
|
Jun. 30, 2013
|
Mar. 31, 2013
|
Dec. 31, 2014
|
Dec. 31, 2013
|
Dec. 31, 2012
|
|
| Consolidated Statements of Income [Abstract] | |||||||||||
| Earnings allocated to participating share awards | $ 11 | $ 11 | $ 12 | $ 12 | $ 11 | $ 12 | $ 13 | $ 11 | $ 46 | $ 47 | $ 49 |