Background and Basis of Presentation (Share Repurchase Program) (Details) (USD $)	12 Months Ended			1 Months Ended	9 Months Ended	1 Months Ended		18 Months Ended	1 Months Ended		9 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Jan. 31, 2011 January 2011 Share Repurchase Program [Member]	Sep. 30, 2011 January 2011 Share Repurchase Program [Member]	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]	Dec. 31, 2013 April 2013 Share Repurchase Program [Member]	Dec. 31, 2013 April 2013 Share Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Planned share repurchase program				$ 1,000,000,000		$ 1,500,000,000	$ 1,000,000,000		$ 1,000,000,000	$ 300,000,000
Repurchase of common stock, shares	16,652,913	34,860,000	49,324,883		37,600,000			48,300,000			15,000,000
Repurchases of common stock, value	600,000,000	1,116,000,000	1,327,000,000								543,000,000
Average price of repurchased shares, per share	$ 36.05	$ 32.00	$ 26.91		$ 26.62			$ 31.06			$ 36.27
Amount remaining in the repurchase program												$ 457,000,000