Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Preferred stock, shares outstanding	5,200,000	5,200,000
Common stock, par value (per share)	$ 1.00	$ 1.00
Common stock, shares authorized	342,857,143	342,857,143
Common stock, shares issued	140,592,409	139,950,422
Common stock, shares outstanding	129,547,032	136,122,843
Treasury stock, shares at cost	11,045,377	3,827,579