Fair Value Measurement - Quantitative Information About Level 3 Fair Value Measurements for Financial Instruments Measured at Fair Value on Nonrecurring Basis (Detail) - Fair Value, Measurements, Nonrecurring [Member] - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Impaired Loans [Member] | Multifamily [Member] | Commercial Loans [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value	$ 424
Impaired Loans [Member] | Multifamily [Member] | Commercial Loans [Member] | Minimum [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	0.00%
Impaired Loans [Member] | Multifamily [Member] | Commercial Loans [Member] | Maximum [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	35.00%
Impaired Loans [Member] | Multifamily [Member] | Commercial Loans [Member] | Weighted Average [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	15.00%
Impaired Loans [Member] | Home Equity [Member] | Consumer Loans [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value	$ 16	$ 228
Impaired Loans [Member] | Home Equity [Member] | Consumer Loans [Member] | Minimum [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	0.00%	0.00%
Impaired Loans [Member] | Home Equity [Member] | Consumer Loans [Member] | Maximum [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	17.85%	17.85%
Impaired Loans [Member] | Home Equity [Member] | Consumer Loans [Member] | Weighted Average [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	8.93%	8.93%
Impaired Loans [Member] | Marine [Member] | Consumer Loans [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value	$ 169
Impaired Loans [Member] | Marine [Member] | Consumer Loans [Member] | Minimum [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	0.00%
Impaired Loans [Member] | Marine [Member] | Consumer Loans [Member] | Maximum [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	37.00%
Impaired Loans [Member] | Marine [Member] | Consumer Loans [Member] | Weighted Average [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	37.00%
Impaired Loans [Member] | Nonresidential [Member] | Commercial Loans [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value		$ 2,257
Impaired Loans [Member] | Nonresidential [Member] | Commercial Loans [Member] | Minimum [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales		0.00%
Impaired Loans [Member] | Nonresidential [Member] | Commercial Loans [Member] | Maximum [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales		35.00%
Impaired Loans [Member] | Nonresidential [Member] | Commercial Loans [Member] | Weighted Average [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales		15.00%
Impaired Loans [Member] | Secured [Member] | Commercial Loans [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value		$ 284
Impaired Loans [Member] | Secured [Member] | Commercial Loans [Member] | Minimum [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales		0.00%
Impaired Loans [Member] | Secured [Member] | Commercial Loans [Member] | Maximum [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales		64.00%
Impaired Loans [Member] | Secured [Member] | Commercial Loans [Member] | Weighted Average [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales		16.00%
Impaired Loans [Member] | Residential Mortgage Loans [Member] | One-to Four-Family [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value	$ 601	$ 919
Impaired Loans [Member] | Residential Mortgage Loans [Member] | One-to Four-Family [Member] | Minimum [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	0.00%	0.00%
Impaired Loans [Member] | Residential Mortgage Loans [Member] | One-to Four-Family [Member] | Maximum [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	10.77%	10.77%
Impaired Loans [Member] | Residential Mortgage Loans [Member] | One-to Four-Family [Member] | Weighted Average [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	4.27%	4.27%
Other Real Estate Owned [Member] | Construction [Member] | Commercial Loans [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value	$ 471	$ 748
Other Real Estate Owned [Member] | Construction [Member] | Commercial Loans [Member] | Minimum [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	0.00%	0.00%
Other Real Estate Owned [Member] | Construction [Member] | Commercial Loans [Member] | Minimum [Member] | Cost Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales		0.00%
Other Real Estate Owned [Member] | Construction [Member] | Commercial Loans [Member] | Maximum [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	24.80%	90.40%
Other Real Estate Owned [Member] | Construction [Member] | Commercial Loans [Member] | Maximum [Member] | Cost Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales		33.33%
Other Real Estate Owned [Member] | Construction [Member] | Commercial Loans [Member] | Weighted Average [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	26.94%	27.46%
Other Real Estate Owned [Member] | Construction [Member] | Commercial Loans [Member] | Weighted Average [Member] | Cost Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales		16.67%
Other Real Estate Owned [Member] | Residential Mortgage Loans [Member] | One-to Four-Family [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value	$ 132	$ 281
Other Real Estate Owned [Member] | Residential Mortgage Loans [Member] | One-to Four-Family [Member] | Minimum [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	0.00%	0.00%
Other Real Estate Owned [Member] | Residential Mortgage Loans [Member] | One-to Four-Family [Member] | Maximum [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	21.00%	27.00%
Other Real Estate Owned [Member] | Residential Mortgage Loans [Member] | One-to Four-Family [Member] | Weighted Average [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	3.85%	7.74%