Consolidated Balance Sheets (Parenthetical) (Unaudited) - $ / shares	Jun. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Preferred stock, par value (usd per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (shares)	5,000,000	5,000,000
Preferred stock, shares issued (shares)	0	0
Preferred stock, shares outstanding (shares)	0	0
Common stock, par value (usd per share)	$ 5.00	$ 5.00
Common stock, shares authorized (shares)	150,000,000	150,000,000
Common stock, shares issued (shares)	59,296,725	59,296,725
Common stock, shares outstanding (shares)	56,350,878	56,200,487
Treasury stock (in shares)	2,945,847	3,096,238