Equity (Changes in Common Stock) (Details)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Repurchases and retirements of common stock	81,000,000	49,000,000	96,000,000
Class A Common Stock [Member]
Common Stock, Shares, Outstanding, Beginning Balance	2,138,075,133	2,122,000,000	2,095,000,000
Stock compensation plans	13,000,000	14,000,000	24,000,000
Repurchases and retirements of common stock	(22,000,000)	0	0
Employee stock purchase plan	2,000,000	2,000,000	3,000,000
Common Stock, Shares, Outstanding, Ending Balance	2,131,137,862	2,138,075,133	2,122,000,000
Class A Special Common Stock [Member]
Common Stock, Shares, Outstanding, Beginning Balance	459,030,180	508,000,000	601,000,000
Stock compensation plans	0	0	3,000,000
Repurchases and retirements of common stock	(59,000,000)	(49,000,000)	(96,000,000)
Employee stock purchase plan	0	0	0
Common Stock, Shares, Outstanding, Ending Balance	400,484,837	459,030,180	508,000,000
Class B Common Stock [Member]
Common Stock, Shares, Outstanding, Beginning Balance	9,444,375	9,000,000	9,000,000
Stock compensation plans	0	0	0
Repurchases and retirements of common stock	0	0	0
Employee stock purchase plan	0	0	0
Common Stock, Shares, Outstanding, Ending Balance	9,444,375	9,444,375	9,000,000

Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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