Loans and Allowance for Credit Losses - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans increased	$ 170,700,000		$ 170,700,000
Percentage of loans decreased	4.00%		4.00%
Charge-offs	4,670,000	10,346,000	13,411,000	30,148,000
Nonperforming loans paid off	900,000
Nonprofit loan, current balance	3,900,000		3,900,000
Loans held for sale	0		0		13,412,000
Nonaccrual	86,730,000		86,730,000		78,476,000
Financing receivable recorded investment nonaccrual status remaining portion	20,800,000		20,800,000
Loans with modifications to rate and payment due to reamortization	700,000	0
Minimum days required for conversion of trouble debt to be in default			90 days
Construction Loan in Florida [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Charge-offs				10,800,000
Real estate construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Charge-offs			1,400,000	4,300,000
Commercial loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Charge-offs			1,200,000	2,000,000
Central pennsylvania [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Charge-offs				5,200,000
Nonaccrual Consumer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	4,800,000		4,800,000
Residential Real Estate Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	4,700,000		4,700,000
Nonaccrual loans status			150
Criticized Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans increased	23,000,000		23,000,000
Percentage of loans decreased	8.00%		8.00%
Loans designated as substandard or doubtful	269,000,000		269,000,000
Percentage of loan portfolio			6.00%
Increase in nonperforming loan			10,300,000
Increase in specific reserves due to troubled debt restructuring			3,200,000
Accruing Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans increased	10,200,000		10,200,000
Percentage of loans decreased	29.00%		29.00%
Non Accrual Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans increased	8,300,000		8,300,000
Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Increase in nonperforming loan			4,900,000
Nonperforming loans	93,900,000		93,900,000		98,800,000
Increase decrease in nonperforming loans	11,300,000		10,300,000
Decrease in specific allowance for nonperforming loans			300,000
Unfunded commitments related to nonperforming loans	5,100,000		5,100,000
Loans held for sale	2,900,000		2,900,000		13,400,000
Nonaccrual	19,300,000		19,300,000
Troubled debt restructured loans decreased			13,100,000
Commitments related to troubled debt restructured loans increased			11,300,000
Loans with modifications to rate and payment due to reamortization			800,000	300,000
Impaired Loans [Member] | Reserve for off balance sheet activities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Off balance sheet reserve to nonperforming loans	44,000		44,000
Impaired Loans [Member] | Waste Management Company In Pennsylvania [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Increase in nonperforming loan			11,300,000
Impaired Loans [Member] | Western Pennsylvania [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired loans under nonperforming status			2,800,000
Nonperforming loans paid off	2,200,000
Financing receivable recorded investment nonaccrual status remaining portion	44,100,000		44,100,000
Principal payment of nonaccrual loans			8,000,000
Nonaccrual loans charge off			15,400,000
Impaired Loans [Member] | Construction Loan in Florida [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual	4,300,000		4,300,000
Financing receivable recorded investment nonaccrual status remaining portion	16,500,000		16,500,000
Impaired Loans [Member] | Commercial real estate loan for retail development in Western Pennsylvania [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired loans under nonperforming status			6,700,000
Nonaccrual	3,900,000		3,900,000
Impaired Loans [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonperforming commercial real estate loans			4,900,000
Impaired Loans [Member] | Medical Equipment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired loans under nonperforming status			2,500,000
Impaired Loans [Member] | Eastern Pennsylvania [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual	16,000,000		16,000,000
Nonaccrual loans charge off			$ 4,200,000