Loans and Allowance for Loan Losses - Additional Information (Detail)	6 Months Ended	12 Months Ended
	Jun. 30, 2015 USD ($) Segment	Dec. 31, 2014 USD ($)	Jun. 30, 2014 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of portfolio segments | Segment	8
Loans on which the accrual of interest has been discontinued	$ 3,818,000	$ 4,826,000
Accrued interest on loans	33,000	100,000
Interest income recorded	$ 300,000	200,000
Trouble Debt restructuring Modified period term	6 months
Period of repayment performance under the modified loan terms	6 months
Non-accruing loans restructured and remained on nonaccrual status	$ 1,200,000		$ 3,400,000
Repayments of loans	0	0
Troubled debt restructuring evaluated impairment	500,000	500,000
Allowance for loans losses	4,000	900,000
Restructured Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructuring evaluated impairment	0
Allowance for loans losses	0
Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan amount threshold for impairment analysis	500,000
Related Party Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Related party loans and commitments	3,000,000	3,100,000
New loans to parties	0	0
Repayments of loan	$ 100,000	$ 500,000
Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of loan portfolio	61.90%	68.50%