Loans and Leases - Summary of Payment Status of Total TDRs (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings ("TDRs")	$ 42,991	$ 41,152
Performing [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings ("TDRs")	11,669	9,441
Non-Performing [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings ("TDRs")	22,916	23,439
Non-Accrual [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings ("TDRs")	$ 8,406	$ 8,272