Commitments, Contingencies and Concentrations of Credit Risk - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Other Commitments [Line Items]
Fixed-rate loan commitments	90 days
Rental expense	$ 2,300,000	$ 2,000,000	$ 2,400,000
Interest payments period	7 years
Accrual Status [Member]
Other Commitments [Line Items]
Amount of interest-only one-to-four family mortgage loans	$ 15,500,000	17,600,000
Amount of stated income loans	22,700,000	27,300,000
Non-Accrual Status [Member]
Other Commitments [Line Items]
Amount of interest-only non-accrual one-to-four family mortgage loans	0	0
Amount of stated income non-accrual loans	$ 19,000	$ 259,000
Minimum [Member]
Other Commitments [Line Items]
Interest rates	3.25%
Interest payments period	5 years
Maximum [Member]
Other Commitments [Line Items]
Interest rates	5.49%
Interest payments period	10 years