Fair Value Measures - Quantitative Information about Level 3 Fair Value Measurements for Financial Instruments Measured at Fair Value on a Non-recurring Basis (Detail) (Fair Value, Measurements, Nonrecurring [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Impaired Loans [Member] | Multi-Family [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value	$ 2,102	$ 2,102
Valuation Technique	Sales comparison approach	Sales comparison approach
Unobservable Inputs	Adjustment for differences between the comparable sales	Adjustment for differences between the comparable sales
Impaired Loans [Member] | Multi-Family [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Range	(11.60%)	(11.60%)
Impaired Loans [Member] | Multi-Family [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Range	20.70%	20.70%
Impaired Loans [Member] | One-To-Four-Family [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value		272
Valuation Technique		Sales comparison approach
Unobservable Inputs		Adjustment for differences between the comparable sales
Impaired Loans [Member] | One-To-Four-Family [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Range		(18.90%)
Impaired Loans [Member] | One-To-Four-Family [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Range		15.00%
Other Real Estate Owned [Member] | Land [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value	102	102
Valuation Technique	Sales comparison approach	Sales comparison approach
Unobservable Inputs	Adjustment for differences between the comparable sales	Adjustment for differences between the comparable sales
Other Real Estate Owned [Member] | Land [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Range	(48.20%)	(48.20%)
Other Real Estate Owned [Member] | Land [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Range	4.50%	4.50%
Other Real Estate Owned [Member] | Commercial Real Estate [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value	$ 389	$ 389
Valuation Technique	Sales comparison approach	Sales comparison approach
Unobservable Inputs	Adjustment for differences between the comparable sales	Adjustment for differences between the comparable sales
Other Real Estate Owned [Member] | Commercial Real Estate [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Range	(1.20%)	(1.20%)
Other Real Estate Owned [Member] | Commercial Real Estate [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Range	(21.70%)	21.70%