Available for sale and held to maturity securities continuous unrealized loss position aggregate losses.

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Available for sale and held to maturity securities continuous unrealized loss position fair value.

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Available for sale and held to maturity securities continuous unrealized loss position less than twelve months aggregate losses.

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Available for sale and held to maturity securities continuous unrealized loss position twelve months or longer aggregate losses.

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Available for sale securities and held to maturity securities continuous unrealized loss position twelve months or longer fair value.

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Amount of the excess of amortized cost basis over fair value of securities that have been in a loss position for twelve months or longer for securities which are categorized neither as held-to-maturity nor trading securities.

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Amount of the excess of amortized cost basis over fair value of securities in a loss position and categorized neither as held-to-maturity nor trading securities.

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Securities - Available for Sale Securities (Unrealized Loss Position) (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
Schedule of Available-for-sale Securities [Line Items]
Fair value less than 12 months, total temporarily impaired securities	$ 9,140	$ 31	$ 21
Gross unrealized losses less than 12 months, total temporarily impaired securities	342
Fair value 12 months or longer, total temporarily impaired securities		3	3
Gross unrealized losses 12 months or longer, total temporarily impaired securities
Fair value, total temporarily impaired securities	9,140	34	24
Gross unrealized losses, total temporarily impaired securities	342
Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair value, less than 12 months	5,380		7
Gross unrealized losses, less than 12 months	225
Fair value, 12 months or longer
Gross unrealized losses, 12 months or longer
Fair Value	5,380		7
Gross unrealized losses, Total	225
Held-to-maturity Securities, Collateralized mortgage obligations Fair Value less than 12 months	3,659
Held-to-maturity Securities, Gross unrealized losses, less than 12 months	115
Held-to-maturity Securities, Collateralized mortgage obligations Fair Value 12 months or longer
Held-to-maturity Securities, Gross unrealized losses, 12 months or longer
Held-to-maturity Securities, Collateralized mortgage obligations Fair Value	3,659
Held-to-maturity Securities, Gross unrealized losses	115
Other Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair value, less than 12 months	94
Gross unrealized losses, less than 12 months	2
Fair value, 12 months or longer
Gross unrealized losses, 12 months or longer
Fair Value	94
Gross unrealized losses, Total	2
Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair value, less than 12 months	2	31	14
Gross unrealized losses, less than 12 months
Fair value, 12 months or longer		3	3
Gross unrealized losses, 12 months or longer
Fair Value	2	34	17
Gross unrealized losses, Total