XML 78 R51.htm IDEA: XBRL DOCUMENT v2.4.0.6
Share-Based Compensation And Benefit Plans (Weighted-Average Assumptions Relating To Valuation Of Our Stock Options) (Details)
12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Share-Based Compensation And Benefit Plans [Abstract]      
Expected term in years 4.25 4.25 4.25
Risk-free interest rate 1.12% 1.14% 1.96%
Expected volatility 32.59% 33.35% 34.03%
Expected dividend yield 3.48% 3.65% 4.32%