Loans Receivable and Allowance for Loan Losses - Troubled Debt Restructuring (Details) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018 USD ($) loan	Sep. 30, 2017 USD ($) loan	Sep. 30, 2018 USD ($) loan	Sep. 30, 2017 USD ($) loan
Financing Receivable, Modifications [Line Items]
No. of Loans \| loan	0	3,000	5,000	7,000
Pre-modification recorded investment	$ 0	$ 4,192	$ 1,050	$ 4,773
Post-modification recorded investment	$ 0	$ 4,192	$ 1,050	$ 791
Real estate loans \| One-to-four family
Financing Receivable, Modifications [Line Items]
No. of Loans \| loan	0	0	4,000	3,000
Pre-modification recorded investment	$ 0	$ 0	$ 462	$ 543
Post-modification recorded investment	$ 0	$ 0	$ 462	$ 543
Real estate loans \| Multifamily and commercial
Financing Receivable, Modifications [Line Items]
No. of Loans \| loan	0	1,000	0	1,000
Pre-modification recorded investment	$ 0	$ 3,964	$ 0	$ 3,964
Post-modification recorded investment	$ 0	$ 3,964	$ 0	$ 0
Commercial business loans \| Commercial Real Estate
Financing Receivable, Modifications [Line Items]
No. of Loans \| loan	0	1,000	0	1,000
Pre-modification recorded investment	$ 0	$ 18	$ 0	$ 18
Post-modification recorded investment	$ 0	$ 18	$ 0	$ 0
Consumer loans \| Home equity loans and advances
Financing Receivable, Modifications [Line Items]
No. of Loans \| loan	0	1,000	1,000	2,000
Pre-modification recorded investment	$ 0	$ 210	$ 588	$ 248
Post-modification recorded investment	$ 0	$ 210	$ 588	$ 248

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Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953676-111524

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Post-modification amount of investment in financing receivables modified by troubled debt restructurings.

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