Long-Term Borrowings - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Overnight funds	$ 215,000,000	$ 100,000,000
FHLB advances	592,069,000	186,411,000
Number of statutory business trusts	12
Outstanding balances of debentures	198,628,000	198,515,000
Maximum time to defer payment of interest on subordinate debt	5 years
Trust Preferred Securities limit percentage	25.00%
Federal Home Loan Bank Borrowings [Member]
Debt Instrument [Line Items]
Carrying value of loans pledged as collateral for FHLB advances	3,065,080,000
Unused borrowing amount	1,413,927,000
Long-Term Borrowings [Member]
Debt Instrument [Line Items]
Interest paid	$ 8,846,000	$ 14,370,000	$ 16,335,000