Goodwill Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2008
Commercial Banking [Member]
Goodwill [Line Items]
Long-term growth rate used in Step 1 of the Goodwill Impairment Test	0.30%
Goodwill Impairment Test Fair Value In Excess Of Carrying Amount Percentage	9.00%
Goodwill, Impairment Loss		$ 750
Branch Banking [Member]
Goodwill [Line Items]
Long-term growth rate used in Step 1 of the Goodwill Impairment Test	1.40%
Goodwill Impairment Test Fair Value In Excess Of Carrying Amount Percentage	4.00%
Consumer Lending [Member]
Goodwill [Line Items]
Goodwill, Impairment Loss		$ 215

Loss recognized during the period that results from the write-down of goodwill after comparing the implied fair value of reporting unit goodwill with the carrying amount of that goodwill. Goodwill is assessed at least annually for impairment.

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+ Details