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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

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 not 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.

Loans - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
Loans - Additional Information (Detail) (USD $)	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of purchased credit impaired loans not covered			91.00%
Average expected life of non covered PCI loans at date of acquisition			4 years
Average expected life of non covered PCI loans at reporting date			2 years 2 months
Non-covered loans net of unearned discount and deferred loan fees	$ 7,300,000		$ 7,300,000		$ 5,600,000
Non-covered loans	11,750,875,000		11,750,875,000		11,471,447,000
Sales of loans	0	0	0	0
Non-interest income, increase (decrease)	7,711,000	2,000,000	7,800,000	5,200,000
Reimbursable portion of valuation write-downs on certain covered OREO properties	(2,192,000)	0	(936,000)	0
Combined loan-to-value ratio home equity loan	75.00%		75.00%
TDRs not reported as non-accrual loans	108,500,000		108,500,000		107,000,000
Non-performing TDRs	23,600,000		23,600,000		48,400,000
Specific reserves for loan losses	2,300,000	3,700,000
Partial loan charge-offs related to loans modified as TDRs	861,000	1,100,000
Number of days loans placed on non-accrual status	90 days		90 days
Contributions to qualified plan	0
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unsecured loans	312,800,000		312,800,000		314,600,000
Commercial and Industrial [Member] \| Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired loans	250,000		250,000
PCI Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding contractual principal balances	92,600,000		92,600,000		227,200,000
Non-covered loans	666,400,000		666,400,000		796,100,000
Consumer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	1,710,904,000		1,710,904,000		1,565,492,000
Unsecured loans	32,400,000		32,400,000		21,400,000
Credit Card [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unsecured loans	$ 7,600,000		$ 7,600,000		$ 8,300,000