Condensed Unaudited Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2019	Dec. 31, 2018
Preferred stock, par value (in dollars per share)	$ 1	$ 1
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, shares authorized	145,000,000	145,000,000
Common stock, shares issued	91,591,398	91,327,009
Treasury stock, shares	15,344,917	15,329,817
Common Stock [Member]
Common stock, shares issued	91,591,398	91,327,009
Restricted Stock Awards [Member] | Common Stock [Member]
Unvested stock awards (in shares)	1,158,549	1,251,533