Earnings Per Common Share (Computation Of Basic And Diluted Earnings (Loss) Per Common Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
NUMERATORS:
Net income	$ 57,607	$ 58,883	$ 159,520	$ 95,076	$ 147,658
Dividends and undistributed earnings allocated to participating securities	84	142	261	338
Net earnings available to common shareholders	$ 57,523	$ 58,741	$ 159,259	$ 94,738
DENOMINATORS:
Weighted average number of common shares outstanding - basic (in shares)	220,297	217,245	220,370	175,627
Effect of potentially dilutive common shares (in shares)	607	1,696	692	1,029
Weighted average number of common shares outstanding - diluted (in shares)	220,904	218,941	221,062	176,656
EARNINGS PER COMMON SHARE:
Basic (in usd per share)	$ 0.26	$ 0.27	$ 0.72	$ 0.54
Diluted (in usd per share)	$ 0.26	$ 0.27	$ 0.72	$ 0.54