Fair Value Measurements - Narrative (Details) $ in Thousands	12 Months Ended
Dec. 31, 2016 USD ($) loan	Dec. 31, 2015 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of non-performing loans held-for-sale \| loan	1
Multi-family mortgage loans (as a percent)		80.00%
Residential mortgage loans (as a percent)		20.00%
Weighted average discount rate	9.94%	9.97%
Weighted average constant prepayment rate on mortgages	10.63%	10.47%
Weighted average life	6 years	6 years 1 month 2 days
REO, net	$ 15,144	$ 19,798
Residential
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans (as a percent)	90.00%	81.00%
Impaired loans for which fair value adjustment was recognized (as a percent)	90.00%	80.00%
Period past due when estimates of collateral values on residential mortgage loans are updated	180 days
Period past due when loan servicer performs property inspections to monitor and manage collateral on residential loans	45 days
REO, net		$ 17,800
Multi-family and commercial real estate mortgage loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans (as a percent)	8.00%	17.00%
Impaired loans for which fair value adjustment was recognized (as a percent)	9.00%	19.00%
Home equity lines of credit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans (as a percent)	2.00%	2.00%
Impaired loans for which fair value adjustment was recognized (as a percent)	1.00%	1.00%
Recurring basis \| Total residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Composition of securities available-for-sale portfolio (as a percent)	90.00%	83.00%
GSE securities in available-for-sale residential mortgage-backed securities portfolio (as a percent)	99.00%	99.00%
Recurring basis \| Obligations of GSEs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Composition of securities available-for-sale portfolio (as a percent)	10.00%	17.00%

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

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

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Impaired Loans, Percent

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Impaired Loans for which Fair Value Adjustment is Recognized, Percent

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- Definition

Number of Non-performing Loans, Held-for-sale

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Percentage Of Available For Sale Residential Mortgage Backed Securities which are Government Sponsored Enterprise Securities.

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Percentage of debt securities comprising securities available-for-sale portfolio.

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- Definition

Percentage of Non-performing Loans Held-for-sale Comprising Multi-family Mortgage Loans

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Percentage of Non-performing Loans Held-for-sale Comprising Residential Mortgage Loans

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

Carrying amount as of the balance sheet date of land and buildings obtained through foreclosure proceedings or defeasance in full or partial satisfaction of a debt arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=49124121&loc=d3e5162-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4437-111522

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 28
-Article 12

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph c
-Subparagraph Schedule III
-Article 5

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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 Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 50
-Paragraph 2
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=56950315&loc=d3e122596-111746

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Estimated rate of prepayments of principal on servicing assets and servicing liabilities.

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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.

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