Loans and Leases (Outstanding Principal Balance and the Related Carrying Amount of Acquired Loans) (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Loans Individually Evaluated For Impairment [Member]
Acquired Loans Unpaid Principal Balance And Related Carrying Amount [Line Items]
Unpaid principal balance	$ 222,596	$ 238,538
Carrying amount	156,525	162,251
Loans Collectively Evaluated For Impairment [Member]
Acquired Loans Unpaid Principal Balance And Related Carrying Amount [Line Items]
Unpaid principal balance	1,851,539	1,976,132
Carrying amount	1,844,879	1,967,032
Purchased Loan [Member]
Acquired Loans Unpaid Principal Balance And Related Carrying Amount [Line Items]
Unpaid principal balance	2,074,135	2,214,670
Carrying amount	$ 2,001,404	$ 2,129,283

The recorded balance, net of any applicable reductions (for example, unamortized accretable yield and other-than-temporary impairments), for loans accounted for as debt securities with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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The undiscounted sum of all amounts, including amounts deemed principal, interest, fees, penalties, and other under the loan, owed to the investor at the reporting date, whether or not currently due and whether or not any such amounts have been written or charged off by the investor. This relates to loans accounted for as debt securities, with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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