Unaudited Condensed Consolidated Balance Sheet (Parenthetical) - $ / shares	Mar. 31, 2017	Dec. 31, 2016
Stockholders' Equity:
Common stock, par value	$ 1	$ 1
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	196,761,485	195,403,644
Common stock, shares outstanding	187,949,951	189,405,244