Consolidated Balance Sheet (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Common stock, par value	$ 0.10	$ 0.10
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares outstanding	78,214,550	77,719,021
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Treasury stock, shares	789,532	630,688