Loans (Narrative) (Detail) (USD $)			6 Months Ended				6 Months Ended		6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2012 Loan Rated Five [Member]	Jun. 30, 2012 Special Mention [Member]	Jun. 30, 2012 Potential Problem And Nonperforming [Member]	Jun. 30, 2012 Doubtful [Member]	Jun. 30, 2012 Maximum [Member]	Jun. 30, 2012 Maximum [Member] Nonperforming Financing Receivable [Member]	Jun. 30, 2012 Minimum [Member]	Jun. 30, 2012 Minimum [Member] Pass [Member]	Jun. 30, 2012 Minimum [Member] Nonperforming Financing Receivable [Member]
Loans [Line Items]
Loans receivable risk rating			5				8		1	1
Debt instrument, credit rating				6	7	6		8			7
Loans and leases receivable, impaired, commitment to lend	$ 9,100,000	$ 16,100,000
Specific reserves on nonaccrual troubled debt restructurings	27,500,000	25,700,000
Specific reserves for accruing TDRs	$ 47,000