Equity (Details) (USD $)	0 Months Ended			3 Months Ended	6 Months Ended	12 Months Ended				0 Months Ended			1 Months Ended	3 Months Ended	12 Months Ended							12 Months Ended			1 Months Ended				3 Months Ended
	Jul. 25, 2013	Apr. 02, 2013	Mar. 25, 2013	Mar. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Jun. 30, 2012	Jan. 29, 2014 Subsequent Event [Member]	Dec. 31, 2013 2013 Repurchase Program [Member]	Dec. 04, 2013 2013 Repurchase Program [Member]	Dec. 31, 2011 2011 Repurchase Program [Member] agreements	Dec. 31, 2013 2011 Repurchase Program [Member]	Dec. 31, 2013 2011 Repurchase Program [Member]	Dec. 31, 2012 2011 Repurchase Program [Member]	Dec. 31, 2011 2011 Repurchase Program [Member] agreements	Dec. 31, 2013 2007 Repurchase Program [Member]	Dec. 31, 2012 2007 Repurchase Program [Member]	Dec. 31, 2011 2007 Repurchase Program [Member]	Dec. 31, 2007 2007 Repurchase Program [Member]	Dec. 31, 2013 Stock Repurchases [Member]	Dec. 31, 2012 Stock Repurchases [Member]	Dec. 31, 2011 Stock Repurchases [Member]	Feb. 28, 2012 Uncollared ASR Agreement [Member]	Dec. 31, 2011 Uncollared ASR Agreement [Member]	Apr. 30, 2012 Capped ASR Agreement [Member]	Dec. 31, 2011 Capped ASR Agreement [Member]	Dec. 31, 2013 Pro Forma [Member] 2011 Repurchase Program [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Treasury Stock, Value, Acquired, Cost Method						$ 989,000,000	$ 298,000,000	$ 1,500,000,000														$ 989,000,000	$ 295,000,000	$ 1,500,000,000
Dividend history
Quarterly dividend rate (in usd per share)						$ 0.28	$ 0.255	$ 0.250		$ 0.30
Annualized dividend rate (in usd per share)						$ 1.12	$ 1.02	$ 1.00
Special dividend (in usd per share)						$ 0	$ 2.50	$ 0
Dividends paid						308,000,000	984,000,000	296,000,000
Share repurchases
Total number of shares purchased (shares)															16,900,000	6,800,000	26,300,000	0	0	8,400,000
Average price paid per share (in usd per share)						$ 58.52	$ 50.35	$ 40.48																					$ 58.36
Total cash utilized					6,145,000,000	6,746,000,000	6,145,000,000
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Balance as of December 31, 2012					810,000,000	810,000,000	810,000,000		810,000,000
Net income attributable to noncontrolling interest					73,000,000
Distributions to noncontrolling interest					(62,000,000)	(22,000,000)	(223,000,000)	(7,000,000)
Redemption value adjustment					(11,000,000)
Balance as of December 31, 2013					810,000,000	810,000,000	810,000,000		810,000,000
Equity (Textual) [Abstract]
Preferred stock authorized (shares)						2,000,000
Par value of Preferred stock (in usd per share)						$ 1
Quarterly dividend rate (in usd per share)						$ 0.28	$ 0.255	$ 0.250		$ 0.30
Stock repurchase program number of shares authorized to be repurchased (shares)												50,000,000	50,000,000				50,000,000				45,000,000
Maximum number of shares authorized for repurchase under stock repurchase plan as percentage of outstanding common stock												18.00%	17.00%				17.00%
Remaining shares available under repurchase program											50,000,000			0	0			0
Number of agreements entered													2				2
Authorized amount			500,000,000										500,000,000													250,000,000		250,000,000
Shares repurchased (in shares)	700,000	1,400,000		7,200,000		9,300,000								100,000											800,000	5,000,000	100,000	5,000,000
Volume weighted-average share price (in dollars per share)	$ 53.7995
Shares repurchased value														$ 10,000,000
Average price paid per share (in usd per share)						$ 58.52	$ 50.35	$ 40.48																					$ 58.36
Interest in joint venture minimum percentage						20.00%
Change in control period						15 days