|
AFS Securities (Key valuation assumptions) (Details) (Auction Rate Securities [Member])
|
3 Months Ended |
|---|---|
|
Mar. 31, 2012
|
|
|
Discounted Cash Flow [Member]
|
|
| Sensitivity Analysis of Fair Value of Interests Continued to be Held by Transferor, Servicing Assets or Liabilities, Impact of Adverse Change in Assumption [Line Items] | |
| Discount rate, valuation basis | LIBOR |
| Discount rate, basis spread on valuation | 6.35% |
|
Credit Yield Analysis [Member]
|
|
| Sensitivity Analysis of Fair Value of Interests Continued to be Held by Transferor, Servicing Assets or Liabilities, Impact of Adverse Change in Assumption [Line Items] | |
| Discount rate, valuation basis | LIBOR |
| Discount rate, basis spread on valuation | 4.00% |
| Average observed discounts based on closed transactions | 14.00% |