Shareholders' Equity (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2012	Mar. 31, 2011
Shareholders' equity activity [Roll Forward]
Balance at beginning of period	$ 13,216	$ 10,387
Transactions with shareholders	94	122
Comprehensive income	637	513
Payments of dividends to shareholders	(83)	(82)
Balance at end of period	13,864	10,940
Company shareholders' equity [Member]
Shareholders' equity activity [Roll Forward]
Balance at beginning of period	13,198	10,373
Transactions with shareholders	95	120
Comprehensive income	634	513
Payments of dividends to shareholders	(83)	(82)
Balance at end of period	13,844	10,924
Noncontrolling interest in consolidated subsidiaries [Member]
Shareholders' equity activity [Roll Forward]
Balance at beginning of period	18	14
Transactions with shareholders	(1)	2
Comprehensive income	3	0
Payments of dividends to shareholders	0	0
Balance at end of period	$ 20	$ 16

The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to the economic entity, including both controlling (parent) and noncontrolling interests. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, including any and all transactions which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

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Total of Stockholders' Equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity including portions attributable to both the parent and noncontrolling interests (previously referred to as minority interest), if any. The entity including portions attributable to the parent and noncontrolling interests is sometimes referred to as the economic entity. This excludes temporary equity and is sometimes called permanent equity.

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