Loans - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013 Contract	Dec. 31, 2012 Contract	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans net of unearned discount and deferred loan fees	$ 5,600,000	$ 3,400,000
Non-covered loans	11,471,447,000	10,842,125,000
Loan portfolio transfer		124,300,000
Sales of loans	0	0
Percentage of total PCI loans not covered	88.00%
Average expected life of non-covered PCI loans at date of acquisition	2 years 6 months
Average expected life of non-covered PCI loans at reporting date	4 years
Decrease in expected credit losses for non covered pools	20,100,000
Non-interest income, increase (decrease)	(8,400,000)	(7,500,000)
Combined loan-to-value ratio home equity loan	75.00%
Accrued interest on non-accrual loans	4,800,000	7,200,000	6,900,000
Interest income recognized and classified as non-accrual	1,300,000	590,000
TDRs not reported as non-accrual loans	107,000,000	105,400,000
Non-performing TDRs	48,400,000	41,800,000
Specific reserves for loan losses	7,900,000	15,000,000
Number of loans modified	82	100
Number of days loans placed on non-accrual status	90 days
Commercial and industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans modified	1
Troubled debt restructuring, charge-offs	1,100,000
Commercial loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans modified	2
Troubled debt restructuring, charge-offs	6,100,000	0
Number of borrowers whose loans were modified	1
PCI Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding contractual principal balances	796,100,000	321,900,000
Non-covered loans	227,200,000	1,100,000,000
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unsecured loans	314,600,000	307,000,000
Commercial and Industrial [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired loans	250,000
Consumer loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-covered loans	1,565,492,000	1,451,717,000
Unsecured loans	21,400,000	44,000,000
Credit Card [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unsecured loans	8,300,000	8,600,000
Covered by FDIC Loss Share [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-interest income, increase (decrease)		$ (5,500,000)