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Receivables from Brokerage Clients - Additional Information (Detail) (USD $)
In Billions, unless otherwise specified |
12 Months Ended | |
|---|---|---|
|
Dec. 31, 2012
|
Dec. 31, 2011
|
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| Receivables from Brokerage Clients [Line Items] | ||
| Margin loans to brokerage clients | $ 11.6 | $ 10.2 |
| Average yield earned on margin loans | 4.08% | 4.39% |