Mortgage Servicing Assets (Details) (USD $)	9 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Mar. 31, 2011
Changes in the carrying amount of mortgage servicing assets
Balance at beginning of Period	$ 196,000,000	$ 221,000,000
Servicing retained from loan sales	15,000,000	5,000,000
Purchases	7,000,000	10,000,000
Amortization	(41,000,000)	(33,000,000)
Balance at end of Period	177,000,000	203,000,000
Fair value at end of Period	260,000,000	295,000,000
Mortgage Servicing Assets (Textual) [Abstract]
Prepayment speed, rate, min	0.00%
Prepayment speed, rate, max	25.00%
Expected credit losses, rate, min	2.00%
Expected credit losses, rate, max	3.00%
Residual cash flows discount rate, min	7.00%
Residual cash flows discount rate, max	15.00%
Interest rate for mortgage funds, min	0.24%
Interest rate for mortgage funds, max	7.18%
Decrease in the assumed default rate of commercial mortgage loans	1.00%
Increase in assumed default rate of commercial mortgage loans	1.00%
Decrease in the fair value of mortgage servicing assets	28,000,000
Decrease in the fair value of mortgage servicing assets due to increase in the assumed default rate of commercial mortgage loans	2,000,000
Contractual fee income from servicing commercial mortgage loans	72,000,000	54,000,000
Escrow Deposit			$ 1,500,000,000

Contractual Fee Income From Servicing Commercial Mortgage Loans.

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- Definition

Decrease In Assumed Default Rate Of Commercial Mortgage Loans.

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- Definition

Decrease In Fair Value Of Mortgage Servicing Assets.

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- Definition

Decrease In Fair Value Of Mortgage Servicing Assets due to increase in the assumed default rate of commercial mortgage loans.

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- Definition

Increase in assumed default rate of commercial mortgage loans.

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- Definition

Mortgage Servicing Assets Expected Credit Losses Maximum.

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Mortgage Servicing Assets Expected Credit Losses Minimum.

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- Definition

Mortgage Servicing Assets Interest Rate For Mortgage Funds Maximum.

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Mortgage Servicing Assets Interest rate for mortgage funds Minimum.

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- Definition

Mortgage Servicing Assets Prepayment Speed Rate Max.

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Mortgage Servicing Assets Prepayment Speed Rate Min.

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Mortgage Servicing Assets Residual Cash Flows Discount Rate Max.

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Mortgage Servicing Assets Residual Cash Flows Discount Rate Min.

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Mortgage Servicing Assets Textual Abstract

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- Definition

Servicing Retained From Loan Sales.

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- Definition

The designation of funds furnished by a borrower to a lender to assure future payments of the borrower's real estate taxes and insurance obligations with respect to a mortgaged property. Escrow deposits may be made for a variety of other purposes such as earnest money and contingent payments. This element excludes replacement reserves which are an escrow separately provided for within the US GAAP taxonomy.

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- Definition

Amortized carrying amount (balance) as of the balance sheet date of an asset representing net future revenues from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements. Rights may be obtained via (1) acquisition or assumption of a servicing obligation that does not relate to financial assets of the servicer or its consolidated affiliates; or (2) by originating loans and then (a) transferring the loans to a qualifying special purpose entity in a transaction that meets the necessary transfer and classification requirements, or (b) transferring the loans in a transaction that meets the requirements for sale accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS140-4 and FIN46(R)-8

-Paragraph B10

-Subparagraph a(1)

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 140

-Paragraph 13A, 13B

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 140

-Paragraph 17

-Subparagraph g(1)(a)

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- Definition

The value of new servicing assets acquired or created during the current period through purchases, assumptions of servicing obligations, and servicing obligations that result from transfers of financial assets.

+ References

+ Details

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- Definition

Decreases in the value of servicing assets due to the periodic mark down in value in proportion to and over the period of estimated net servicing income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 140

-Paragraph 17

-Subparagraph g(1)(d)

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS140-4 and FIN46(R)-8

-Paragraph B10

-Subparagraph a(4)

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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- Definition

Fair value of the servicing asset that has been amortized as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 140

-Paragraph 17

-Subparagraph g(2)

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 140

-Paragraph 68

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