Earnings Per Common Share (Calculations) (Details) - $ / shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share, Diluted [Abstract]
Weighted average common shares outstanding	236,500,000	236,700,000
Effect of dilutive securities:
Stock options	500,000	700,000
Other stock compensation plans	700,000	600,000
Potentially dilutive common shares	1,200,000	1,300,000
Adjusted weighted average common shares outstanding	237,700,000	238,000,000.0
Dividends per common share (in dollars per share)	$ 0.0051	$ 0.0048
Outstanding stock options excluded from the computation of diluted earnings per share due to their antidilutive effect	1,500,000	1,600,000