Loans and Leases (Outstanding Principal Balance and the Related Carrying Amount of Acquired Loans) (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Loans Individually Evaluated For Impairment [Member]
Acquired Loans Unpaid Principal Balance And Related Carrying Amount [Line Items]
Unpaid principal balance	$ 129,457	$ 176,351
Carrying amount	106,836	138,445
Loans Collectively Evaluated For Impairment [Member]
Acquired Loans Unpaid Principal Balance And Related Carrying Amount [Line Items]
Unpaid principal balance	1,322,877	1,509,870
Carrying amount	1,325,716	1,506,695
Purchased Loan [Member]
Acquired Loans Unpaid Principal Balance And Related Carrying Amount [Line Items]
Unpaid principal balance	1,452,334	1,686,221
Carrying amount	$ 1,432,552	$ 1,645,140