Earnings Per Common Share (Calculations) (Details) - $ / shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Earnings Per Share, Diluted [Abstract]
Weighted average common shares outstanding	237,800	236,600	237,600	236,600
Effect of dilutive securities:
Stock options	1,200	300	1,000	400
Other stock compensation plans	800	700	800	600
Potentially dilutive common shares	2,000	1,000	1,800	1,000
Adjusted weighted average common shares outstanding	239,800	237,600	239,400	237,600
Dividends per common share (in dollars per share)	$ 0.54	$ 0.51	$ 1.08	$ 1.02
Outstanding stock options excluded from the computation of diluted earnings per share due to their antidilutive effect	0	2,700	0	2,100