Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	200,000	200,000
Liquidation preference (in dollars per share)	$ 1,000	$ 1,000
Common stock, par value (in dollars per share)	$ 2.50	$ 2.50
Common stock, shares authorized (in shares)	600,000,000	600,000,000
Common stock, shares issued (in shares)	223,200,000	223,200,000
Treasury stock, shares (in shares)	60,700,000	60,800,000