Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Preferred stock, par or stated value per share	$ 1	$ 1
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Common stock, par or stated value per share	$ 1	$ 1
Common stock, shares authorized	800,000,000	800,000,000
Common stock, shares issued	446,100,000	508,100,000
Treasury stock, shares	23,300,000	22,900,000