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								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
NUMERATORS:
Net income	$ 63,019	$ 57,607	$ 54,784	$ 47,129	$ 52,582	$ 58,883	$ 17,542	$ 18,651	$ 222,539	$ 147,658	$ 98,291
Dividends and undistributed earnings allocated to participating securities	96	84	93	84	146	142	83	113	357	484	788
Net earnings available to common shareholders	$ 62,923	$ 57,523	$ 54,691	$ 47,045	$ 52,436	$ 58,741	$ 17,459	$ 18,538	$ 222,182	$ 147,174	$ 97,503
DENOMINATORS:
Weighted average number of common shares outstanding - basic									220,327	186,550	111,938
Effect of potentially dilutive common shares									718	994	238
Weighted average number of common shares outstanding - diluted									221,045	187,544	112,176
EARNINGS PER COMMON SHARE:
Basic earnings per common share (usd per share)	$ 0.29	$ 0.26	$ 0.25	$ 0.21	$ 0.24	$ 0.27	$ 0.09	$ 0.17	$ 1.01	$ 0.79	$ 0.87
Diluted earnings per common share (usd per share)	$ 0.28	$ 0.26	$ 0.25	$ 0.21	$ 0.24	$ 0.27	$ 0.09	$ 0.16	$ 1.01	$ 0.78	$ 0.87