Shareholders' Equity (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Shareholders' equity activity [Roll Forward]
Balance at beginning of period			$ 13,216	$ 10,387
Transactions with shareholders			241	299
Comprehensive income	603	682	1,984	1,937
Payments of dividends to shareholders			(250)	(247)
Balance at end of period	15,191	12,376	15,191	12,376
Company shareholders' equity
Shareholders' equity activity [Roll Forward]
Balance at beginning of period			13,198	10,373
Transactions with shareholders			243	299
Comprehensive income			1,977	1,933
Payments of dividends to shareholders			(250)	(247)
Balance at end of period	15,168	12,358	15,168	12,358
Noncontrolling interest in consolidated subsidiaries
Shareholders' equity activity [Roll Forward]
Balance at beginning of period			18	14
Transactions with shareholders			(2)	0
Comprehensive income			7	4
Payments of dividends to shareholders			0	0
Balance at end of period	$ 23	$ 18	$ 23	$ 18

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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