Earnings Per Share (Comparison Of Basic And Diluted Earnings Per Share) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Earnings Per Share, Basic [Abstract]
Net income	$ 30,915	$ 122,843	$ 359,750	$ 279,973
Weighted average common shares outstanding	96,458,231	101,974,077	97,926,378	103,020,681
Basic earnings per share	$ 0.32	$ 1.20	$ 3.67	$ 2.72
Earnings Per Share, Diluted [Abstract]
Net income	$ 30,915	$ 122,843	$ 359,750	$ 279,973
Weighted average common shares outstanding	96,458,231	101,974,077	97,926,378	103,020,681
Share equivalents:
Warrants and options	1,430,243	1,500,342	1,449,641	1,492,374
RSUs and LTIP awards	541,711	708,399	575,675	877,107
Employee share purchase plan	14,053	1,761	13,602	3,114
Weighted average common shares and common share equivalents outstanding - diluted	98,444,238	104,184,579	99,965,296	105,393,276
Diluted earnings per share	$ 0.31	$ 1.18	$ 3.60	$ 2.66