Troubled Debt Restructurings, Subsequently Defaulted (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	4	1
Defaulted payment following modification for troubled debt restructurings	$ 1,942	$ 527
Commercial and Industrial Loans and Leases [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	1	1
Defaulted payment following modification for troubled debt restructurings	565	527
Commercial Real Estate Loans [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	3	0
Defaulted payment following modification for troubled debt restructurings	$ 1,377	$ 0