Loans - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2015 SecurityLoan	Dec. 31, 2014 SecurityLoan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Troubled debt restructuring loans	$ 3,667,000	$ 3,736,000
Number of loans modified as troubled debt restructurings	0	0
Number of non-accruing troubled debt restructured loans	3	3
Non-accruing troubled debt restructured loans	521,000	548,000
Troubled debt restructuring, number of loans agreed to pay	2
Payment of troubled debt restructurings	448,000
Troubled debt restructurings, payment default period	90 days
Troubled debt restructurings, subsequent payment default	0	231,000
Allowance for credit losses, recoveries		60,000
Troubled debt restructuring loans	3,667,000	3,736,000
Troubled Debt Restructurings [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Troubled debt restructuring loans	2,863,000	2,904,000
Troubled debt restructuring loans reserve	253,000	293,000
Troubled debt restructuring loans	$ 2,863,000	$ 2,904,000