Common and Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Common: Par value $.25, 600,000,000 shares authorized
Treasury stock	39,638,264	38,421,636
Issued - December 31	296,000,000
Common Stock, par value and shares authorized
Common stock, par value per share	$ 0.25		$ 0.25
Common stock shares authorized	600,000,000		600,000,000
Payments For Repurchase Of Common Stock	$ 139	$ 413