Investment Securities - Additional Information (Detail) - USD ($)	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Held to maturity mortgage-backed securities sales		$ 1,400,000
Mortgage-backed securities principal paid down		90.00%
Gain on sales of mortgage-backed securities		$ 73,000
Securities, carrying value	$ 351,500,000		$ 356,100,000
Purchase price of equities	2,700,000
Market value of equities	4,800,000
Equity securities included in investment funds	13,500,000
Investment in community development loans	$ 2,900,000
Redemption of funds	60 days
Investment in government guaranteed loans, mortgage-backed securities, small business loans	$ 10,600,000
Amortized cost of securities	10,800,000
Fair value of securities	10,600,000
Unfunded commitments	$ 0