Stock Compensation Plans (Principal Assumptions For SSAR's Granted Fair Value) (Details) (USD $)	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Stock Compensation Plans [Abstract]
Weighted average fair value of SSAR's granted during the period	$ 11.47	$ 10.41	$ 7.08
Risk-free interest rate	1.70%	2.20%	2.50%
Expected volatility	23.20%	29.80%	30.90%
Expected dividend yield	2.10%	2.20%	3.20%
Expected life, in years	5	5	5
Termination rate	0.99%	1.09%	0.91%
Exercise multiple	1.43	1.38	1.46

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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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.

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- Definition

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.

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