Earnings and Dividends per Share (Reconciliation Of Denominator For Basic And Diluted Earnings (Loss) Per Share) (Details) - $ / shares	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Weighted average common shares—basic									129,401,823	129,087,043	129,367,712
Plus incremental shares from: Assumed exercise of options									583,930	452,970	607,110
Weighted average common shares—diluted									129,985,753	129,540,013	129,974,822
Basic (in dollars per share)	$ 0.95	$ 2.36	$ 2.13	$ 2.21	$ 6.18	$ 1.62	$ 1.18	$ 1.07	$ 7.66	$ 10.05	$ 3.07
Diluted (in dollars per share)	$ 0.95	$ 2.35	$ 2.12	$ 2.20	$ 6.15	$ 1.61	$ 1.17	$ 1.06	$ 7.62	$ 10.00	$ 3.06