Employee Stock Ownership Plan - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	May. 12, 1998
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Purchase of common stock shares	2,013,137
Fixed interest rate	8.25%
Contributions to ESOP	$ 510,000	$ 512,000
Dividends paid unallocated ESOP shares	204,000	209,000
Outstanding loan	$ 3,500,000	$ 3,700,000
Unallocated shares of ESOP	360,995	394,816
Fair value of unallocated shares	$ 7,200,000
Shares allocated to participants	2,252,070
Shares committed to be released	33,821
Minimum [Member]
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Extended loan term	12 years
Maximum [Member]
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Extended loan term	30 years
Employee Stock Ownership Plan [Member]
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Minimum age limit for employees to participate in ESOP	21 years
Minimum number of working hours	1000 hours
ESOP original borrowings	$ 13,400,000
Additional common stock shares				633,750
Additional borrowings				$ 8,200,000
Expiration period	2026
Compensation expense related to ESOP	$ 603,000	$ 570,000	$ 538,000
Increase in the average fair value	$ 318,000	$ 284,000	$ 250,000