FAIR VALUE MEASUREMENTS (Details 5) (USD $)	3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013
Financial Assets:
Interest-earning deposits in financial institutions	$ 228,579,000	$ 50,998,000
Loans and leases, net	4,079,887,000	4,230,318,000	3,374,744,000
Other real estate owned
Period of appraisals for Level 2 measurement	12 months
Non-PCI Loans
Financial Assets:
Loans and leases, net	3,768,571,000	3,869,315,000
Impaired loans (excluding PCI loans)
Nonaccrual loans	58,100,000	46,800,000
Amount of nonaccrual loans written down to fair values through charge-offs	0
Minimum
Impaired loans (excluding PCI loans)
Threshold of unpaid principal balance of non-purchased credit impaired nonaccrual loans for individual evaluation of impairment	250,000
Minimum | Non-PCI Loans
Impaired loans (excluding PCI loans)
Threshold of unpaid principal balance of non-purchased credit impaired nonaccrual loans for individual evaluation of impairment	250,000
Maximum
Impaired loans (excluding PCI loans)
Threshold of unpaid principal balance of non-purchased credit impaired nonaccrual loans for collective evaluation of impairment	250,000
Maximum | Non-PCI Loans
Impaired loans (excluding PCI loans)
Threshold of unpaid principal balance of non-purchased credit impaired nonaccrual loans for collective evaluation of impairment	250,000
Total
Financial Assets:
Cash and due from banks	113,508,000	96,424,000
Interest-earning deposits in financial institutions	228,579,000	50,998,000
Securities available-for-sale	1,477,473,000	1,494,745,000
Investment in FHLB stock	25,000,000	27,939,000
Loans and leases, net	4,089,647,000	4,231,078,000
SBA loan servicing asset	764,000	807,000
Financial Liabilities:
Demand, money market, interest checking and savings deposits	4,719,833,000	4,616,616,000
Time deposits	649,824,000	665,148,000
Borrowings	5,748,000	113,726,000
Subordinated debentures	132,649,000	132,498,000
Level 1
Financial Assets:
Cash and due from banks	113,508,000	96,424,000
Interest-earning deposits in financial institutions	228,579,000	50,998,000
Securities available-for-sale	509,000	507,000
Financial Liabilities:
Borrowings		106,600,000
Level 2
Financial Assets:
Securities available-for-sale	1,439,370,000	1,456,334,000
Investment in FHLB stock	25,000,000	27,939,000
Loans and leases, net	5,284,000	2,051,000
Financial Liabilities:
Demand, money market, interest checking and savings deposits	4,719,833,000	4,616,616,000
Time deposits	649,824,000	665,148,000
Borrowings	5,748,000	7,126,000
Subordinated debentures	132,649,000	132,498,000
Level 3
Financial Assets:
Securities available-for-sale	37,594,000	37,904,000
Loans and leases, net	4,084,363,000	4,229,027,000
SBA loan servicing asset	764,000	807,000
Carrying or Contract Amount
Financial Assets:
Cash and due from banks	113,508,000	96,424,000
Interest-earning deposits in financial institutions	228,579,000	50,998,000
Securities available-for-sale	1,477,473,000	1,494,745,000
Investment in FHLB stock	25,000,000	27,939,000
Loans and leases, net	4,079,887,000	4,230,318,000
SBA loan servicing asset	764,000	807,000
Financial Liabilities:
Demand, money market, interest checking and savings deposits	4,719,833,000	4,616,616,000
Time deposits	649,575,000	664,371,000
Borrowings	5,748,000	113,726,000
Subordinated debentures	$ 132,790,000	$ 132,645,000