Stockholders' Equity (Share Repurchase Program) (Narrative) (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended	9 Months Ended		20 Months Ended
	Sep. 30, 2015	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Jul. 28, 2015	Jan. 21, 2015	Jan. 31, 2014
Equity, Class of Treasury Stock [Line Items]
Prepayments / repurchase of common stock		$ 2,353	$ 2,000
January 2014 Buyback Plan [Member]
Equity, Class of Treasury Stock [Line Items]
Share buyback plan, Authorized Amount							$ 5,000
Repurchased and retired, shares				34.7
Repurchase of common stock				$ 2,353
YTD 2015 Open Market Purchases [Member]
Equity, Class of Treasury Stock [Line Items]
Repurchased and retired, shares		4.6
Repurchase of common stock		$ 353
2015 Share Buyback Plan [Member]
Equity, Class of Treasury Stock [Line Items]
Share buyback plan, Authorized Amount					$ 2,000
Prepayments / repurchase of common stock	$ 2,000
Repurchased and retired, shares	28.8
Percentage of share repurchase agreement completed	80.00%	80.00%		80.00%
2015 Share buyback announcement						$ 4,000