Recorded Investment and Principal Balance of Impaired Loans by Portfolio Segment Their Related Allowance for Loan and Lease Losses and Interest Income Recognized (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012		Sep. 30, 2012
Financing Receivable, Impaired [Line Items]
Recorded investment of impaired lease with related allowance	$ 19,408	[1]	$ 21,790	[2]	$ 21,637	[1]
Impaired loans with related allowance
Financing Receivable, Impaired [Line Items]
Recorded investment of impaired lease with related allowance	7,660	[1]	11,967	[2]	9,413	[1]
Impaired loans without related allowance
Financing Receivable, Impaired [Line Items]
Recorded investment of impaired lease with related allowance	11,748	[1],[3],[4]	9,823	[2],[5]	12,224	[1],[3],[6]
Leases | Impaired loans with related allowance
Financing Receivable, Impaired [Line Items]
Recorded investment of impaired lease with related allowance					223
Leases | Impaired loans without related allowance
Financing Receivable, Impaired [Line Items]
Recorded investment of impaired lease with related allowance	$ 62		$ 168

[1] Recorded investment equals principal balance less partial charge-offs and interest payments on non-performing loans that have been applied to principal.

[2] Recorded investment equals principal balance less partial charge-offs and interest payments on non-performing loans that have been applied to principal

[3] This table excludes all purchased credit-impaired loans, which are discussed in Note 5D, above.

[4] The table above does not include the recorded investment of $62 thousand of impaired leases without a related Allowance.

[5] The table above does not include the recorded investment of $168 thousand of impaired leases without a related Allowance.

[6] The table above does not include the recorded investment of $223 thousand of impaired leases without a related allowance for loan and lease losses.