Net Income Per Common Share (Schedule Of Basic And Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Basic Earnings (Loss) Per Share
Net income available to common shareholders	$ 69,298	$ 49,972
Weighted average common shares outstanding (in shares)	122,300	127,227
Net income per common share, basic (in dollars per share)	$ 0.57	$ 0.39
Diluted Earnings (Loss) Per Share
Net income available to common shareholders	$ 69,298	$ 49,972
Weighted average common shares outstanding (in shares)	122,300	127,227
Potentially dilutive shares from outstanding equity-based awards (in shares)	759	630
Weighted average number of diluted common shares (in shares)	123,059	127,857
Net income per common share, diluted (in dollars per share)	$ 0.56	$ 0.39