Background and Basis of Presentation Share Repurchase Program (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended	18 Months Ended			3 Months Ended	18 Months Ended			3 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Mar. 31, 2013 October 2011 Share Repurchase Program [Member]	Oct. 31, 2012 October 2011 Share Repurchase Program [Member]	Oct. 31, 2011 October 2011 Share Repurchase Program [Member]	Sep. 30, 2014 April 2013 Share Repurchase Program [Member]	Sep. 30, 2014 April 2013 Share Repurchase Program [Member]	Aug. 31, 2013 April 2013 Share Repurchase Program [Member]	Apr. 30, 2013 April 2013 Share Repurchase Program [Member]	Sep. 30, 2014 July 2014 Share Repurchase Program [Member]	Jul. 31, 2014 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	6.4	4.5	17.2	9.9		48.3			1.3	27.1			5.1
Repurchases of common stock, value	275,000,000	156,000,000	679,000,000	348,000,000	600,000,000				53,000,000				222,000,000
Average price of repurchased shares, per share	$ 42.87	$ 34.75	$ 39.44	$ 35.20		$ 31.06			$ 41.39	$ 36.97			$ 43.24
Amount remaining in the repurchase program													$ 778,000,000