Earnings Per Share (Computation Of Basic And Diluted Earnings Per Share) (Details) (USD $) In Thousands, except Share data	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Earnings Per Share [Abstract]
Net income attributable to common shareholders	$ 52,540	$ 41,507	$ 151,444	$ 114,782
Average basic shares outstanding	58,048,000	58,608,000	58,202,000	58,710,000
Effect of dilutive stock options	1,010,000	917,000	1,128,000	935,000
Average diluted shares outstanding	59,058,000	59,525,000	59,330,000	59,645,000
Earnings per basic share	$ 0.91	$ 0.71	$ 2.60	$ 1.96
Earnings per diluted share	$ 0.89	$ 0.70	$ 2.55	$ 1.92
Average options excluded from computation of diluted earnings per share	1,000,000	2,000,000	800,000	2,600,000