Capital Stock And Share-Based Compensation (Schedule Of Employee Stock Purchase Plan Period) (Details) (Employee Stock Purchase Plan [Member], USD $)	12 Months Ended
	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Issued	2,142,223
2009 And Prior [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Issued	1,642,504
Issue Price	12.18
January 1, 2010 To March 31, 2010 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Issued	33,377
Issue Price	46.94
April 1, 2010 To June 30, 2010 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Issued	44,902
Issue Price	37.38
July 1, 2010 To September 30, 2010 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Issued	74,836
Issue Price	20.23
October 1, 2010 To December 31, 2010 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Issued	55,413
Issue Price	28.48
January 1, 2011 To March 31, 2011 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Issued	38,752
Issue Price	29.75
April 1, 2011 To June 30, 2011 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Issued	54,323
Issue Price	22.64
July 1, 2011 To September 30, 2011 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Issued	94,301
Issue Price	12.60
October 1, 2011 To December 31, 2011 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Issued	103,815
Issue Price	9.27