Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Detail) - Credit Quality Indicators by Class, Excluding Covered Loans (Continued) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Home equity
Credit Quality Indicators by Class, Excluding Covered Loans [Line Items]
Credit Quality Indicators by Class	$ 427,020	$ 390,033
1-4 family mortgages
Credit Quality Indicators by Class, Excluding Covered Loans [Line Items]
Credit Quality Indicators by Class	275,992	282,948
Installment
Credit Quality Indicators by Class, Excluding Covered Loans [Line Items]
Credit Quality Indicators by Class	44,827	38,394
Total consumer loans
Credit Quality Indicators by Class, Excluding Covered Loans [Line Items]
Credit Quality Indicators by Class	747,839	711,375
Performing | Home equity
Credit Quality Indicators by Class, Excluding Covered Loans [Line Items]
Credit Quality Indicators by Class	420,156	383,844
Performing | 1-4 family mortgages
Credit Quality Indicators by Class, Excluding Covered Loans [Line Items]
Credit Quality Indicators by Class	270,794	278,074
Performing | Installment
Credit Quality Indicators by Class, Excluding Covered Loans [Line Items]
Credit Quality Indicators by Class	42,751	38,394
Performing | Total consumer loans
Credit Quality Indicators by Class, Excluding Covered Loans [Line Items]
Credit Quality Indicators by Class	733,701	700,312
Non-accrual | Home equity
Credit Quality Indicators by Class, Excluding Covered Loans [Line Items]
Credit Quality Indicators by Class	6,864	6,189
Non-accrual | 1-4 family mortgages
Credit Quality Indicators by Class, Excluding Covered Loans [Line Items]
Credit Quality Indicators by Class	5,198	4,874
Non-accrual | Installment
Credit Quality Indicators by Class, Excluding Covered Loans [Line Items]
Credit Quality Indicators by Class	2,076	0
Non-accrual | Total consumer loans
Credit Quality Indicators by Class, Excluding Covered Loans [Line Items]
Credit Quality Indicators by Class	$ 14,138	$ 11,063