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Employee Stock And Savings Plans (Schedule Of Estimation Assumptions Used) (Details)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Employee Stock And Savings Plans [Abstract]
Expected life (in years)	6.6	6.6	6.5
Average risk-free interest rate	2.90%	3.30%	2.30%
Expected volatility	31.00%	31.90%	33.70%
Expected dividend yield	0.00%	0.00%	0.00%

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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