Summary of Financial Effects of Troubled Debt Restructurings (Detail) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018 USD ($) Investment	Jun. 30, 2017 USD ($) Investment	Jun. 30, 2018 USD ($) Investment	Jun. 30, 2017 USD ($) Investment
Financing Receivable, Modifications [Line Items]
Number of loans classified as a non-accrual TDRs \| Investment		16	13	34
Pre-Modification Recorded Investment		$ 23,296	$ 6,680	$ 31,523
Post-Modification Recorded Investment		19,379	4,074	24,145
Trouble debt restructuring, charge-off amount		825	$ 2,476	4,104
Capitalized interest		$ 7		$ 12
Acquisition, Development and Construction
Financing Receivable, Modifications [Line Items]
Number of loans classified as a non-accrual TDRs \| Investment			1
Pre-Modification Recorded Investment			$ 900
Post-Modification Recorded Investment			$ 900
Weighted Average Interest Rate, Pre-Modification			4.50%
Weighted Average Interest Rate, Post-Modification			4.50%
Commercial and Industrial
Financing Receivable, Modifications [Line Items]
Number of loans classified as a non-accrual TDRs \| Investment	6	13	12	30
Pre-Modification Recorded Investment	$ 2,613	$ 22,752	$ 5,780	$ 30,714
Post-Modification Recorded Investment	$ 1,420	$ 18,722	$ 3,174	$ 23,151
Weighted Average Interest Rate, Pre-Modification	3.27%	3.49%	3.27%	3.45%
Weighted Average Interest Rate, Post-Modification	3.05%	3.45%	3.14%	3.45%
Trouble debt restructuring, charge-off amount	$ 1,158	$ 825	$ 2,476	$ 4,104
One-to-four family
Financing Receivable, Modifications [Line Items]
Number of loans classified as a non-accrual TDRs \| Investment		3
Pre-Modification Recorded Investment		$ 544
Post-Modification Recorded Investment		$ 657
Weighted Average Interest Rate, Pre-Modification		5.90%
Weighted Average Interest Rate, Post-Modification		2.00%
Capitalized interest		$ 7
Multi-Family
Financing Receivable, Modifications [Line Items]
Number of loans classified as a non-accrual TDRs \| Investment				4
Pre-Modification Recorded Investment				$ 809
Post-Modification Recorded Investment				$ 994
Weighted Average Interest Rate, Pre-Modification				5.93%
Weighted Average Interest Rate, Post-Modification				2.21%
Capitalized interest				$ 12

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

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
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Post-modification amount of investment in financing receivables modified by troubled debt restructurings.

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Reflects the amount of the write-down related to a troubled debt restructuring.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=82895541&loc=d3e18845-111554

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The gross interest income that would have been recorded in the period on troubled debt restructurings, if the loans had been current in accordance with their original terms and had been outstanding throughout the period or since origination, if held for part of the period.

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