Background and Basis of Presentation Share Repurchase Program (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended	1 Months Ended		18 Months Ended	1 Months Ended		6 Months Ended	1 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Oct. 31, 2012 October 2011 Share Repurchase Program [Member]	Oct. 31, 2011 October 2011 Share Repurchase Program [Member]	Mar. 31, 2013 October 2011 Share Repurchase Program [Member]	Aug. 31, 2013 April 2013 Share Repurchase Program [Member]	Apr. 30, 2013 April 2013 Share Repurchase Program [Member]	Jun. 30, 2014 April 2013 Share Repurchase Program [Member]	Jul. 31, 2014 Subsequent Event [Member] July 2014 Share Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Planned share repurchase program						$ 1,500,000,000	$ 1,000,000,000		$ 1,000,000,000	$ 300,000,000		$ 1,000,000,000
Repurchase of common stock, shares	3.3	3.7	10.8	5.4				48.3
Repurchases of common stock, value	132,000,000	135,000,000	404,000,000	192,000,000	600,000,000
Average price of repurchased shares, per share	$ 40.72	$ 36.27	$ 37.40	$ 35.58				$ 31.06
Amount remaining in the repurchase program											$ 53,000,000