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, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Jul. 26, 2012 Dividend Declared [Member]	Jun. 30, 2012 Common Stock [Member]	Jun. 30, 2011 Common Stock [Member]	Jun. 30, 2012 Treasury Stock [Member]	Jun. 30, 2011 Treasury Stock [Member]	Jun. 30, 2012 Parent [Member]	Jun. 30, 2011 Parent [Member]	Jun. 30, 2012 Noncontrolling Interest [Member]	Jun. 30, 2011 Noncontrolling Interest [Member]
Reconciliation of the beginning and ending balances of the carrying amount of equity
Balance as of beginning of period			$ 16,445	$ 15,025						$ 16,423	$ 15,025	$ 22	$ 0
Net income (loss)	830	743	398	841						399	842	(1)	(1)
Dividends			(166)	(57)						(166)	(57)	0	0
Stock-based compensation expense			20	23						20	23	0	0
Tax deduction in excess of stock-based compensation expense			3	11						3	11	0	0
Transactions in connection with stock-based compensation plans:
Stock issuances			11	30						11	30	0	0
Stock repurchases			(136)	(2)						(136)	(2)	0	0
Contributions from noncontrolling interest			25	11						0	0	25	11
Other comprehensive income	(102)	19	23	110						23	110	0	0
Balance as of end of period	$ 16,623	$ 15,992	$ 16,623	$ 15,992						$ 16,577	$ 15,982	$ 46	$ 10
Share Activity Rollforward
Common stock, shares, beginning balance						673,000,000	673,000,000
Treasury stock, shares, beginning balance			116,689,450					(117,000,000)	(105,000,000)
Stock issuances, stock-based compensation						0	0	1,000,000	2,000,000
Stock purchases, stock-based compensation								(6,000,000)	0
Common stock, shares, ending balance						673,000,000	673,000,000
Treasury Stock, shares, ending balance	122,106,373		122,106,373					(122,000,000)	(103,000,000)
Equity (Textual)
Dividends payable, date declared					Jul. 26, 2012
Dividends payable, amount per share					$ 0.175
Dividends payable, date to be paid					Sep. 12, 2012
Dividends payable, date of record					Aug. 15, 2012