Shareholders' Equity And Net Income Per Share Share Repurchase Program (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	12 Months Ended
	Feb. 02, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share Repurchase Program [Line Items]
Stock Repurchased During Period, Shares		9,481,946	14,581,705	15,041,713
Stock Repurchased, Average Price		$ 66.93	$ 79.48	$ 68.05
Stock Repurchased During Period, Value		$ 635	$ 1,159	$ 1,024
Share Repurchase Program April 2016
Share Repurchase Program [Line Items]
Stock Repurchase Program, Authorized Amount		1,500
Stock Repurchase Program, Remaining Authorized Repurchase Amount		1,372
Share Repurchase Program January 2015
Share Repurchase Program [Line Items]
Stock Repurchase Program, Authorized Amount		$ 1,500
Subsequent Event
Share Repurchase Program [Line Items]
Stock Repurchased During Period, Value	$ 23
Subsequent Event | Share Repurchase Program April 2016
Share Repurchase Program [Line Items]
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 1,349