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, 2018	Mar. 31, 2017
Basic Earnings (Loss) Per Share
Net income available to common shareholders	$ 100,607	$ 69,298
Weighted average common shares outstanding (in shares)	118,666	122,300
Net income per common share, basic (in dollars per share)	$ 0.85	$ 0.57
Diluted Earnings (Loss) Per Share
Net income available to common shareholders	$ 100,607	$ 69,298
Weighted average common shares outstanding (in shares)	118,666	122,300
Potentially dilutive shares from outstanding equity-based awards and Earnout Payments (in shares)	655	759
Weighted average number of diluted common shares (in shares)	119,321	123,059
Net income per common share, diluted (in dollars per share)	$ 0.84	$ 0.56