Stockholders Equity (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Equity, Class of Treasury Stock [Line Items]
Treasury Stock, Value, Acquired, Cost Method	$ 8	$ 1,015	$ 513
Share Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Remaining Authorized Repurchase Amount	1,500
Authorized Stock Repurchase Program Repurchase Amount	$ 4,700
Authorized Stock Repurchase Program Repurchased Number Of Shares	121
Treasury Stock, Value, Acquired, Cost Method		$ 1,000
Treasury Stock, Shares, Acquired		29