Earnings Per Common Share (Computation Of Basic And Diluted Earnings (Loss) Per Common Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share [Abstract]
Net income	$ 420,300	$ (1,523,420)	$ 354,095
Weighted average number of common shares outstanding - basic	219,032	220,218	220,339
Effect of potentially dilutive common shares (1)	549	0	311
Weighted average number of common shares outstanding - diluted	219,581	220,218	220,650
Earnings (loss) per common share:
Basic earnings per common share (usd per share)	$ 1.92	$ (6.92)	$ 1.61
Diluted earnings per common share (usd per share)	$ 1.91	$ (6.92)	$ 1.60