Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2018	Dec. 31, 2017
Condensed Consolidated Balance Sheets [Abstract]
Common stock, par value	$ 1	$ 1
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	93,400,000	93,400,000
Common stock, shares outstanding	84,100,000	84,000,000