Earnings Per Share (Comparison Of Basic And Diluted Earnings Per Share) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Basic earnings per share:
Net income	$ 124,356	$ 176,972
Weighted average common shares outstanding	95,935,551	99,545,187
Basic earnings per share	$ 1.30	$ 1.78
Diluted earnings per share:
Net income	$ 124,356	$ 176,972
Weighted average common shares outstanding	95,935,551	99,545,187
Share equivalents:
Warrants and options	1,116,871	1,463,958
RSUs and performance-based equity awards	509,971	565,611
Employee share purchase plan	14,636	9,906
Weighted average common shares and common share equivalents outstanding - diluted	97,577,029	101,584,662
Diluted earnings per share	$ 1.27	$ 1.74