Loans - Schedule of Portfolio of Loans (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014
Financing Receivable Allowance For Credit Losses [Line Items]
Total loans	$ 1,413,505		$ 1,332,593
Allowance for loan losses	17,172	$ 16,903	17,712	$ 16,881	$ 17,221	$ 17,687
Deferred loan costs, net	(1,773)		(1,311)
Total	15,399		16,401
Loans, net	1,398,106		1,316,192
Commercial Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Total loans	437,428		369,752
Allowance for loan losses	8,958	8,521	8,077	6,389	5,945	5,690
Commercial Loans [Member] | Multifamily [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Total loans	81,022		80,170
Commercial Loans [Member] | Nonresidential [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Total loans	196,110		175,456
Commercial Loans [Member] | Land [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Total loans	9,748		9,301
Commercial Loans [Member] | Construction [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Total loans	61,744		38,812
Commercial Loans [Member] | Secured [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Total loans	84,390		63,182
Commercial Loans [Member] | Unsecured [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Total loans	4,414		2,831
Residential Mortgage Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Total loans	782,805		774,583
Allowance for loan losses	5,644	5,736	6,630	7,082	7,666	8,517
Residential Mortgage Loans [Member] | Construction [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Total loans	35,275		40,898
Residential Mortgage Loans [Member] | One-to Four-Family [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Total loans	747,530		733,685
Consumer Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Total loans	193,272		188,258
Allowance for loan losses	2,570	$ 2,646	3,005	$ 3,410	$ 3,610	$ 3,480
Consumer Loans [Member] | Home Equity [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Total loans	160,206		161,338
Consumer Loans [Member] | Auto [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Total loans	19,580		11,348
Consumer Loans [Member] | Marine [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Total loans	2,208		2,699
Consumer Loans [Member] | Recreational Vehicle [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Total loans	8,691		10,656
Consumer Loans [Member] | Other [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Total loans	$ 2,587		$ 2,217