Stockholders' Equity (Share Repurchase Program) (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended			23 Months Ended	35 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2016	Dec. 31, 2016	Jul. 28, 2015	Jan. 21, 2015	Jan. 31, 2014
Equity, Class of Treasury Stock [Line Items]
Payments for Repurchase of Common Stock	$ 916	$ 2,353	$ 2,000
Repurchased and retired, shares	13,152,000	39,564,000	30,110,000
2015 Share Buyback Plan [Member]
Equity, Class of Treasury Stock [Line Items]
2015 Share Buyback Announcement							$ 4,000
Share buyback plan, authorized amount						$ 2,000
Payments for Repurchase of Common Stock				$ 2,916
Repurchased and retired, shares				48,200,000
YTD 2016 Open Market Purchases [Member]
Equity, Class of Treasury Stock [Line Items]
Payments for Repurchase of Common Stock	$ 916
Repurchased and retired, shares	13,200,000
January 2014 Buyback Plan [Member]
Equity, Class of Treasury Stock [Line Items]
Share buyback plan, authorized amount								$ 5,000
Payments for Repurchase of Common Stock			$ 2,000		$ 2,353
Repurchased and retired, shares			30,100,000		34,700,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 2,647			$ 2,647	$ 2,647
YTD 2015 Open Market Purchases [Member]
Equity, Class of Treasury Stock [Line Items]
Payments for Repurchase of Common Stock		$ 353
Repurchased and retired, shares		4,600,000