Fair Value Measurements (Details 4)	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011
Valuation methodologies used for assets measured at fair value
Impaired loans comprising residential mortgage loans (as a percent)	78.00%	81.00%
Impaired loans comprising multi-family and commercial real estate loans (as a percent)	22.00%	19.00%
Impaired loans for which fair value adjustment is recognized comprising residential mortgage loans (as a percent)	84.00%	93.00%
Impaired loans for which fair value adjustment is recognized comprising multi-family and commercial real estate loans (as a percent)	16.00%	7.00%
Weighted average
Valuation methodologies used for assets measured at fair value
Assumption to estimate fair value of servicing asset, weighted average discount rate (as a percent)	10.95%	10.94%
Assumption to estimate fair value of servicing asset, weighted average constant prepayment rate (as a percent)	23.12%	20.30%
Assumption to estimate fair value of servicing asset, weighted average life	3 years 4 months 24 days	3 years 8 months 12 days
Residential
Valuation methodologies used for assets measured at fair value
Period after which loans are individually evaluated for impairment	180 days
Period past due when loan servicer performs property inspections	45 days

The past due period of time after which all loans are individually evaluated for impairment.

No definition available.

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- Definition

Represents the period of time past due when loan servicer performs property inspections to monitor and manage collateral.

+ References

No definition available.

+ Details

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- Definition

Represents the percentage of impaired loans comprising multi-family and commercial real estate loans.

+ References

No definition available.

+ Details

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- Definition

Represents the percentage of impaired loans comprising residential mortgage loans.

+ References

No definition available.

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- Definition

Represents the percentage of impaired loans for which fair value adjustment is recognized, comprising multi-family and commercial real estate loans.

+ References

No definition available.

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- Definition

Represents the percentage of impaired loans for which fair value adjustment is recognized, comprising residential mortgage loans.

+ References

No definition available.

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- Definition

The discount rate used to estimate the fair value of servicing assets and servicing liabilities.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 140

-Paragraph 17

-Subparagraph f

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS140-4/FIN46R-8

-Paragraph B8

-Subparagraph d

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Definition

The estimated speed of prepayments of principal on financial assets which may be one of the factors applied in estimating the fair value of servicing assets and servicing liabilities.

+ References

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- Definition

Weighted average life of financial assets and financial liabilities, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

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