Investments in equity securities (Detail) (USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010
Investments in equity securities [Line Items]
Cost Basis	$ 45,960	$ 35,544
Unrealized Gains	24,646	26,641
Unrealized Losses	(2,544)	(672)
Fair Value	68,062	61,513
Equity Securities [Member] \| Banks, insurance and finance [Member]
Investments in equity securities [Line Items]
Cost Basis	15,985	15,519
Unrealized Gains	8,370	9,549
Unrealized Losses	(2,308)	(454)
Fair Value	22,047	24,614
Equity Securities [Member] \| Consumer products [Member]
Investments in equity securities [Line Items]
Cost Basis	12,564	13,551
Unrealized Gains	12,986	12,410
Unrealized Losses	(18)	(212)
Fair Value	25,532	25,749
Equity Securities [Member] \| Commercial, industrial and other [Member]
Investments in equity securities [Line Items]
Cost Basis	17,411	6,474
Unrealized Gains	3,290	4,682
Unrealized Losses	(218)	(6)
Fair Value	$ 20,483	$ 11,150

Investments in equity securities [Line Items]

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- Definition

For an unclassified balance sheet, this item represents the cost basis, net of adjustments made for accretion, amortization, other-than-temporary impairments, and hedging, if any, of investments in common and preferred stocks and other forms of securities that provide ownership interests in a corporation.

+ Details

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- Definition

This item represents the total unrealized holding gain on marketable equity securities, at reporting date.

+ Details

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- Definition

This item represents the total unrealized holding loss on marketable equity securities, at reporting date.

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- Definition

For an unclassified balance sheet, this item represents investments in common and preferred stocks and other forms of securities that provide ownership interests in a corporation.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 7

-Section 03

-Paragraph 1

-Subparagraph b

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.1(b))

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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