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Share-Based Compensation (Summary Of Weighted Average Assumptions Used For Options Granted) (Details)	12 Months Ended
	Dec. 31, 2011 years	Dec. 31, 2010 years	Dec. 31, 2009 years
Share-Based Compensation [Abstract]
Expected life (in years)	6.7	6.7	6.5
Expected volatility	33.10%	35.00%	37.20%
Risk-free interest rate	1.70%	2.70%	3.10%
Expected forfeiture rate	3.00%	3.00%	3.00%

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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