Loans Receivable and Allowance for Loan Losses (Narrative) (Detail) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2015 Borrowers SecurityLoan TDRs	Mar. 31, 2014	Dec. 31, 2014 Borrowers SecurityLoan TDRs	May 30, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Principal amount of nonaccrual loans	$ 50,900,000		$ 53,900,000
Loans less than 90 days past due	7,300,000		8,400,000
Impaired loan defined floor limit	1,000,000.0
Impaired loans number	153		147
Impaired loans	90,808,000		85,395,000
Number of troubled debt restructurings	131		123
Number of borrowers	123		120
Loans and leases receivable, impaired, nonperforming, accrual of interest	61,700,000		54,800,000
Weighted average modified interest rate	5.90%	4.31%
Weighted average prior modification rate	5.83%	5.23%
Interest and Dividend Income, Operating	72,231,000	64,523,000
Allowances for loan losses	6,653,000		7,127,000
Average balance of impaired loans	91,438,000	87,869,000
Team Capital Bank [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Allowance for Loan Losses, Decreases	225,000
Fair value of acquired PCI loans				5,220,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net	4,300,000			4,500,000
Interest and Dividend Income, Operating	76,000
Impaired Loans - Trouble Debt Restructurings [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Allowances for loan losses	31,000	41,000
No Allowance for Loan Losses Required [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired financing receivable with no related allowance	22,710,000		18,346,000
With Related Allowance For Loan Losses [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Allowances for loan losses	$ 6,653,000		$ 7,127,000