Federal Home Loan Bank Advances (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
First Mortgage [Member]
Debt Instrument [Line Items]
Collateral	$ 46,900,000
Multi-family mortgage loans [Member]
Debt Instrument [Line Items]
Collateral	$ 358,900,000
Federal Home Loan Bank Advances [Member] \| Within 1 year [Member]
Debt Instrument [Line Items]
Borrowings, Contractual Rate	2.51%	1.34%
Borrowings, Amount	$ 20,000,000	$ 60,000,000
Federal Home Loan Bank Borrowings [Member]
Debt Instrument [Line Items]
Increase in line of credit	311,800,000
Letter of Credit [Member] \| Federal Home Loan Bank Advances [Member]
Debt Instrument [Line Items]
Outstanding balance	$ 0	$ 0

Amount of assets pledged to secure a debt instrument.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 470
-Section 50
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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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Amount of unused borrowing capacity under the long-term financing arrangement that is available to the entity as of the balance sheet date.

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Represents the aggregate of total long-term debt, including current maturities and short-term debt.

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Weighted average interest rate of debt outstanding.

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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