Key Economic Assumptions - Mortgage Servicing Assets (Details)	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Securitizations and Variable Interest Entities [Abstract]
Prepayment speed (annual CPR)	13.10%	13.60%	12.00%	13.00%
Life (in years)	5.9	5.4	6.2	5.6
Discount rate	7.90%	8.00%	7.90%	8.20%

The discount rate which is used to value residual cash flows generated by financial assets of the securitization, asset-backed financing arrangement, or similar transfer. This is used as a key assumption in measuring the fair value of assets or liabilities that relate to a transferor's assets obtained or liabilities incurred, if any, at the time of securitization, asset-backed financing, or similar transfer.

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Estimated speed of prepayments of principal on financial assets. This is used as a key assumption in measuring the fair value of assets obtained or liabilities incurred that relate to a transferor's continuing involvement, if any, at the time of securitization, asset-backed financing, or similar transfer.

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- Definition

The weighted average life of securitized assets. This is used as a key input and assumption in measuring the fair value of assets obtained or liabilities incurred that relate to a transferor's continuing involvement, if any, at the time of securitization, asset-backed financing, or similar transfer.

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