Stockholders' Equity (Share Repurchase Program) (Narrative) (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended	6 Months Ended		17 Months Ended
	Jun. 30, 2015	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jul. 28, 2015	Jan. 21, 2015	Jan. 31, 2014
Equity, Class of Treasury Stock [Line Items]
Repurchase of common stock		$ 353	$ 1,061
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
Q2 2015 Open Market Purchases [Member]
Equity, Class of Treasury Stock [Line Items]
Repurchased and retired, shares	1.0
YTD 2015 Open Market Purchases [Member]
Equity, Class of Treasury Stock [Line Items]
Repurchased and retired, shares		4.6
2015 Share Buyback Plan [Member]
Equity, Class of Treasury Stock [Line Items]
2015 Share buyback announcement						$ 4,000
Subsequent Event [Member] | 2015 Share Buyback Plan [Member]
Equity, Class of Treasury Stock [Line Items]
Share buyback plan, Authorized Amount					$ 2,000