Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2012

Stock-Based Compensation [Abstract]

Schedule Of Fair Value Of The Restricted Stock Awards Granted During The Periods

	Three Months Ended March 31,
	2012			2011
Shares granted		367,936			192,581
Estimated fair value (in millions)	$	15.6		$	10.0
Percentage of shares granted expected to be distributed		89	%		93	%