CONSOLIDATED BALANCE SHEETS (unaudited) (Parenthetical) - $ / shares	Mar. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Preferred Stock, shares authorized (in shares)	100,000,000	100,000,000
Preferred Stock, shares issued (in shares)	5,200,000	5,200,000
Preferred stock, shares outstanding (in shares)	5,200,000	5,200,000
Common stock, par value (USD per share)	$ 1.00	$ 1.00
Common stock, shares authorized (in shares)	342,857,143	342,857,143
Common stock, shares issued (in shares)	143,017,301	142,677,449
Common stock, shares outstanding (in shares)	118,702,497	118,897,295
Treasury stock, shares at cost (in shares)	24,314,804	23,780,154