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
	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018
Earnings Per Share [Abstract]
Net income	$ 74,033	$ 80,311	$ 90,981	$ 65,999	$ 78,972
Weighted average number of common shares outstanding - basic (in shares)	220,366				220,370
Effect of potentially dilutive common shares (in shares)	289				455
Weighted average number of common shares outstanding - diluted (in shares)	220,655				220,825
EARNINGS PER COMMON SHARE:
Basic (in usd per share)	$ 0.34				$ 0.36
Diluted (in usd per share)	$ 0.34				$ 0.36