XML 18 R54.htm IDEA: XBRL DOCUMENT v2.4.0.6
Equity Based Compensation Plans Weighted average assumptions (Details) (USD $)
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Weighted average fair value assumptions [Abstract]      
Stock price (in dollars per share) $ 143.95 $ 131.87 $ 107.21
Risk-free interest rates (in hundredths) 1.16% 2.23% 3.50%
Expected lives, minimum 7 years    
Expected lives, maximum 10 years    
Expected lives   10 years 10 years
Volatility (in hundredths) 20.05% 19.63% 22.00%
Dividend yield (in hundredths) 3.26% 3.29% 3.85%