Loans - Loans Receivable to Loans Held for Sale (Detail) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013 Real Estate Loans [Member]	Mar. 31, 2012 Real Estate Loans [Member]	Mar. 31, 2013 Commercial and Industrial Loans [Member]	Mar. 31, 2012 Commercial and Industrial Loans [Member]	Dec. 31, 2012 Consumer Loans [Member]	Dec. 31, 2011 Consumer Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Balance at Beginning of Period	$ 8,306,000	$ 22,587,000		$ 11,068,000	$ 8,306,000	$ 11,519,000
Origination of Loans Held For Sale	23,144,000	25,866,000			23,144,000	25,866,000
Reclassification from Loans Receivable to Loans Held for Sale	3,373,000	37,481,000		17,076,000	3,373,000	20,405,000
Reclassification from Loans Receivable to Other Real Estate Owned		(360,000)		(360,000)
Sales of Loans Held for Sale	(28,765,000)	(28,697,000)		(16,794,000)	(28,765,000)	(11,903,000)
Principal Payoffs and Amortization	(15,000)	(227,000)		(111,000)	(15,000)	(116,000)
Valuation Adjustments		(657,000)				(657,000)
Balance at End of Period	$ 6,043,000	$ 55,993,000		$ 10,879,000	$ 6,043,000	$ 45,114,000