Earnings Per Share (Comparison Of Basic And Diluted Earnings Per Share) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Earnings Per Share, Basic [Abstract]
Net income	$ 151,863	$ (1,862)	$ 328,835	$ 157,130
Weighted average common shares outstanding	97,809,639	103,267,659	98,672,618	103,552,656
Basic earnings per share	$ 1.55	$ (0.02)	$ 3.33	$ 1.52
Earnings Per Share, Diluted [Abstract]
Net income	$ 151,863	$ (1,862)	$ 328,835	$ 157,130
Weighted average common shares outstanding	97,809,639	103,267,659	98,672,618	103,552,656
Share equivalents:
Warrants and options	1,448,071	0	1,456,439	1,479,675
RSUs and LTIP awards	455,744	0	550,224	913,587
Employee share purchase plan	11,348	0	12,287	3,867
Weighted average common shares and common share equivalents outstanding - diluted	99,724,802	103,267,659	100,691,568	105,949,785
Diluted earnings per share	$ 1.52	$ (0.02)	$ 3.27	$ 1.48