LOAN PORTFOLIO - Credit Risk Payment Activity (Parenthetical) (Detail) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Financing Receivable Recorded Investment [Line Items]
Residential mortgage loans insured by FHA or guaranteed by the VA	$ 30,100,000	$ 40,400,000
Period of residential mortgage loan that are no longer accruing interest	1 year 6 months 0 days	1 year 6 months 0 days
Loans considered to be defaulted if borrower has failed to make payment for a period or more than the period	0 years 2 months 29 days	0 years 2 months 29 days
Loans held for sale	81,723,000	76,956,000
Non Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans held for sale	54,600,000	54,600,000
Non Accrual [Member] | Commercial Construction [Member]
Financing Receivable Recorded Investment [Line Items]
Loans held for sale	39,100,000	39,100,000
Non Accrual [Member] | Residential Construction [Member]
Financing Receivable Recorded Investment [Line Items]
Loans held for sale	900,000	900,000
Non Accrual [Member] | Land Construction [Member]
Financing Receivable Recorded Investment [Line Items]
Loans held for sale	7,800,000	7,800,000
Non Accrual [Member] | Commercial mortgage [Member]
Financing Receivable Recorded Investment [Line Items]
Loans held for sale		$ 6,800,000	$ 6,800,000