Consolidated Balance Sheet (Parenthetical) - $ / shares	Dec. 31, 2015	Dec. 31, 2014
Stockholders' equity:
Common stock, par value (in dollars per share)	$ 1.00	$ 1.00
Common stock, shares authorized (in shares)	2,000,000,000	2,000,000,000
Common stock, shares issued (in shares)	807,611,634	807,611,634
Treasury stock, at cost: shares (in shares)	160,010,017	132,071,550