XML 72 R94.htm IDEA: XBRL DOCUMENT v2.4.0.6
Share-Based Compensation And Capital Stock Weighted Average Assumptions Of Black-Scholes Option-Pricing Model (Details) (Stock Options, USD $)
In Millions, except Share data, unless otherwise specified
12 Months Ended
Dec. 31, 2011
years
Dec. 31, 2010
years
Dec. 31, 2009
years
Stock Options
     
Risk-free interest rate 2.10% 2.19% 1.82%
Expected volatility 39.51% 41.92% 39.71%
Expected life of a stock option 4.4 4.4 4.4
Dividend yield 1.79% 2.26% 2.74%
Requisite service period 4 years 4 years 4 years
Contractual life 7 7 7
Weighted average fair value of options granted $ 12.42 $ 10.07 $ 7.41
Options granted 166,306 261,137 537,006
Options granted, fair value $ 2.1 $ 2.6 $ 4.0