Fair Value (Quantitative Information About Recurring Level Three Fair Value Measurements ) (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended										6 Months Ended										3 Months Ended	6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013 Corporate	Dec. 31, 2012 Corporate	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Commercial [Member] Impaired Loans [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Residential Real Estate [Member] Home Equity Line Of Credit [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Non Residential Real Estate [Member] Commercial Mortgage Loans, Owner Occupied [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Non Residential Real Estate [Member] Commercial Mortgage Loans, Non Owner Occupied [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Construction [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Cost Sales Income Approach Valuation Technique [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Cost Sales Income Approach Valuation Technique [Member] Residential Other Real Estate Owned [Member] Other Real Estate [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Cost Sales Income Approach Valuation Technique [Member] Non Residential Other Real Estate Owned [Member] Other Real Estate [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Cost Sales Income Approach Valuation Technique [Member] Commercial [Member] Impaired Loans [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Cost Sales Income Approach Valuation Technique [Member] Residential Real Estate [Member] Residential Real Estate Other Financing Receivable [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Cost Sales Income Approach Valuation Technique [Member] Residential Real Estate [Member] Home Equity Line Of Credit [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Cost Sales Income Approach Valuation Technique [Member] Non Residential Real Estate [Member] Commercial Mortgage Loans, Owner Occupied [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Cost Sales Income Approach Valuation Technique [Member] Non Residential Real Estate [Member] Commercial Mortgage Loans, Non Owner Occupied [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Cost Sales Income Approach Valuation Technique [Member] Construction [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Corporate	Dec. 31, 2012 Significant Unobservable Inputs (Level 3) [Member] Corporate	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Corporate Discounted Cash Flows Valuation Technique [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Maximum [Member] Cost Sales Income Approach Valuation Technique [Member] Residential Other Real Estate Owned [Member] Other Real Estate [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Maximum [Member] Cost Sales Income Approach Valuation Technique [Member] Non Residential Other Real Estate Owned [Member] Other Real Estate [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Maximum [Member] Cost Sales Income Approach Valuation Technique [Member] Commercial [Member] Impaired Loans [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Maximum [Member] Cost Sales Income Approach Valuation Technique [Member] Residential Real Estate [Member] Residential Real Estate Other Financing Receivable [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Maximum [Member] Cost Sales Income Approach Valuation Technique [Member] Residential Real Estate [Member] Home Equity Line Of Credit [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Maximum [Member] Cost Sales Income Approach Valuation Technique [Member] Non Residential Real Estate [Member] Commercial Mortgage Loans, Owner Occupied [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Maximum [Member] Cost Sales Income Approach Valuation Technique [Member] Non Residential Real Estate [Member] Commercial Mortgage Loans, Non Owner Occupied [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Maximum [Member] Cost Sales Income Approach Valuation Technique [Member] Construction [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Minimum [Member] Cost Sales Income Approach Valuation Technique [Member] Residential Other Real Estate Owned [Member] Other Real Estate [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Minimum [Member] Cost Sales Income Approach Valuation Technique [Member] Non Residential Other Real Estate Owned [Member] Other Real Estate [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Minimum [Member] Cost Sales Income Approach Valuation Technique [Member] Commercial [Member] Impaired Loans [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Minimum [Member] Cost Sales Income Approach Valuation Technique [Member] Residential Real Estate [Member] Residential Real Estate Other Financing Receivable [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Minimum [Member] Cost Sales Income Approach Valuation Technique [Member] Residential Real Estate [Member] Home Equity Line Of Credit [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Minimum [Member] Cost Sales Income Approach Valuation Technique [Member] Non Residential Real Estate [Member] Commercial Mortgage Loans, Owner Occupied [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Minimum [Member] Cost Sales Income Approach Valuation Technique [Member] Non Residential Real Estate [Member] Commercial Mortgage Loans, Non Owner Occupied [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member] Minimum [Member] Cost Sales Income Approach Valuation Technique [Member] Construction [Member]	Jun. 30, 2013 Fair Value, Measurements, Recurring [Member] Significant Unobservable Inputs (Level 3) [Member] Corporate Discounted Cash Flows Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Investment securities available-for-sale	$ 306,546	$ 314,444	$ 995	$ 1,060															$ 995	$ 1,060																		$ 995
Probability of default																					0.00%
Impaired loans	$ 1,169,651	$ 1,182,273			$ 1,540	$ 184	$ 7,547	$ 749	$ 754	$ 17,288	$ 283	$ 2,121		$ 4,110
Unobservable Input, discounts ranging											0.00%	0.00%	50.00%	11.00%	8.00%	5.00%	4.00%	13.00%				0.00%	0.00%	100.00%	100.00%	100.00%	100.00%	100.00%	100.00%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%
Valuation Techniques	Valuation Technique(s)										Cost, sales, income approach	Cost, sales, income approach	Cost, sales, income approach	Cost, sales, income approach	Cost, sales, income approach	Cost, sales, income approach	Cost, sales, income approach	Cost, sales, income approach