FAIR VALUE MEASUREMENTS (Details 5) (USD $)	3 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011
Financial Assets:
Interest-earning deposits in financial institutions	$ 71,036,000	$ 203,275,000
Loans and leases, net	3,549,145,000	3,425,423,000	3,564,586,000	3,622,661,000
Non-covered impaired loans
Nonaccrual loans	37,000,000	58,300,000
Amount of nonaccrual loans written down to fair values through charge-offs	3,500,000
Other real estate owned
Period of appraisals for Level 2 measurement	12 months
Minimum
Non-covered impaired loans
Threshold of unpaid principal balance of non-covered nonaccrual loans for individual evaluation of impairment	250,000
Maximum
Non-covered impaired loans
Threshold of unpaid principal balance of non-covered nonaccrual loans for collective evaluation of impairment	250,000
Total
Financial Assets:
Cash and due from banks	89,370,000	92,342,000
Interest-earning deposits in financial institutions	71,036,000	203,275,000
Securities available-for-sale	1,357,211,000	1,326,358,000
Investment in FHLB stock	40,923,000	46,106,000
Loans and leases, net	3,609,672,000	3,469,754,000
SBA loan servicing asset	1,059,000	1,613,000
Financial Liabilities:
Demand, money market and savings deposits	3,925,007,000	3,609,559,000
Time deposits	868,038,000	977,589,000
Borrowings	18,024,000	249,000,000
Subordinated debentures	108,195,000	135,532,000
Level 1
Financial Assets:
Cash and due from banks	89,370,000	92,342,000
Interest-earning deposits in financial institutions	71,036,000	203,275,000
Securities available-for-sale	8,159,000	2,976,000
Level 2
Financial Assets:
Securities available-for-sale	1,303,165,000	1,278,233,000
Investment in FHLB stock	40,923,000	46,106,000
Loans and leases, net	5,247,000	13,803,000
Financial Liabilities:
Demand, money market and savings deposits	3,925,007,000	3,609,559,000
Time deposits	868,038,000	977,589,000
Borrowings	18,024,000	249,000,000
Subordinated debentures	108,195,000	135,532,000
Level 3
Financial Assets:
Securities available-for-sale	45,887,000	45,149,000
Loans and leases, net	3,604,425,000	3,455,951,000
SBA loan servicing asset	1,059,000	1,613,000
Carrying or Contract Amount
Financial Assets:
Cash and due from banks	89,370,000	92,342,000
Interest-earning deposits in financial institutions	71,036,000	203,275,000
Securities available-for-sale	1,357,211,000	1,326,358,000
Investment in FHLB stock	40,923,000	46,106,000
Loans and leases, net	3,549,145,000	3,425,423,000
SBA loan servicing asset	1,059,000	1,613,000
Financial Liabilities:
Demand, money market and savings deposits	3,925,007,000	3,609,559,000
Time deposits	862,341,000	967,894,000
Borrowings	17,996,000	225,000,000
Subordinated debentures	$ 108,250,000	$ 129,271,000