Stock-Based Compensation Plans (Details 8) (Stock Appreciation Rights [Member])	12 Months Ended
Dec. 31, 2011 Y	Dec. 31, 2010 Y	Dec. 31, 2009 Y
Stock Appreciation Rights [Member]
Summary of fair value of stock appreciation rights
Expected dividend yield	2.39%	1.33%	1.57%
Risk-free interest rate	0.62%	1.46%	1.78%
Expected volatility	41.94%	39.93%	39.81%
Expected life (in years)	4.07	4.04	4.12

The period of time an equity-based award is expected to be outstanding. An equity-based award's expected term is generally determined based on, among other factors, the instrument's contractual term and the effects of employees' expected exercise and post-vesting employment termination behavior.

+ References+ Details

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

+ References+ Details