Equity (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended		0 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Jul. 25, 2013 Subsequent Event [Member] Dividend Declared [Member]	Jun. 30, 2013 Shares Purchased Related To Stock-Based Compensation Plans [Member]	Jun. 30, 2012 Shares Purchased Related To Stock-Based Compensation Plans [Member]	Jun. 30, 2013 Shares Purchased Under Programs [Member]	Jun. 30, 2012 Shares Purchased Under Programs [Member]	Jun. 30, 2013 Parent [Member]	Jun. 30, 2012 Parent [Member]	Jun. 30, 2013 Parent [Member] Shares Purchased Related To Stock-Based Compensation Plans [Member]	Jun. 30, 2012 Parent [Member] Shares Purchased Related To Stock-Based Compensation Plans [Member]	Jun. 30, 2013 Parent [Member] Shares Purchased Under Programs [Member]	Jun. 30, 2012 Parent [Member] Shares Purchased Under Programs [Member]	Jun. 30, 2013 Common Stock [Member]	Jun. 30, 2012 Common Stock [Member]	Jun. 30, 2013 Treasury Stock [Member]	Jun. 30, 2012 Treasury Stock [Member]	Jun. 30, 2013 Treasury Stock [Member] Shares Purchased Related To Stock-Based Compensation Plans [Member]	Jun. 30, 2012 Treasury Stock [Member] Shares Purchased Related To Stock-Based Compensation Plans [Member]	Jun. 30, 2013 Treasury Stock [Member] Shares Purchased Under Programs [Member]	Jun. 30, 2012 Treasury Stock [Member] Shares Purchased Under Programs [Member]	Jun. 30, 2013 Noncontrolling Interest [Member]	Jun. 30, 2012 Noncontrolling Interest [Member]	Jun. 30, 2013 Noncontrolling Interest [Member] Shares Purchased Related To Stock-Based Compensation Plans [Member]	Jun. 30, 2012 Noncontrolling Interest [Member] Shares Purchased Related To Stock-Based Compensation Plans [Member]	Jun. 30, 2013 Noncontrolling Interest [Member] Shares Purchased Under Programs [Member]	Jun. 30, 2012 Noncontrolling Interest [Member] Shares Purchased Under Programs [Member]
Reconciliation of the Beginning and Ending Balances of the Carrying Amounts of Equity
Balance as of beginning of period			$ 18,095	$ 16,445						$ 18,032	$ 16,423													$ 63	$ 22
Net income (loss)	465	830	1,117	398						1,120	399													(3)	(1)
Dividends			(220)	(166)						(220)	(166)													0	0
Stock-based compensation expense			25	20						25	20													0	0
Tax deduction in excess of stock-based compensation expense			27	3						27	3													0	0
Transactions in connection with stock-based compensation plans:
Stock issuances			43	11						43	11													0	0
Stock repurchases						(196)	(136)	(364)	0			(196)	(136)	(364)	0											0	0	0	0
Separation of retail business			(499)	0						(499)	0													0	0
Contributions from noncontrolling interests			45	25						0	0													45	25
Other comprehensive income (loss)	(61)	(102)	(48)	23						(48)	23													0	0
Balance as of end of period	$ 18,025	$ 16,623	$ 18,025	$ 16,623						$ 17,920	$ 16,577													$ 105	$ 46
Share Activity
Common stock, shares, beginning balance																673,000,000	673,000,000
Treasury stock, shares, beginning balance			(121,406,520)															(121,000,000)	(117,000,000)
Stock issuances, stock-based compensation																0	0	3,000,000	1,000,000
Stock purchases, stock-based compensation																				(5,000,000)	(6,000,000)	(8,000,000)	0
Common stock, shares, ending balance																673,000,000	673,000,000
Treasury Stock, shares, ending balance	(131,412,237)		(131,412,237)															(131,000,000)	(122,000,000)
Equity (Textual)
Dividends payable, date declared					Jul. 25, 2013
Dividends payable, amount per share					$ 0.225
Dividends payable, date to be paid					Sep. 11, 2013
Dividends payable, date of record					Aug. 14, 2013