LOANS (excluding covered loans) - Loan Delinquency, including Nonaccrual Loans (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans, excluding covered loans	$ 3,430,916,000	$ 3,179,064,000
Non Covered Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 days past due	12,574,000	12,367,000
60 - 89 days past due	5,246,000	5,411,000
> 90 days past due	42,692,000	41,660,000
Total Past due	60,512,000	59,438,000
Current	3,370,404,000	3,119,626,000
Total loans, excluding covered loans	3,430,916,000	3,179,064,000
> 90 days past due and still accruing	265,000	212,000
Non Covered Loans | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 days past due	1,018,000	1,770,000
60 - 89 days past due	678,000	832,000
> 90 days past due	9,294,000	4,197,000
Total Past due	10,990,000	6,799,000
Current	949,026,000	854,234,000
Total loans, excluding covered loans	960,016,000	861,033,000
> 90 days past due and still accruing	0	0
Non Covered Loans | Real estate-construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 days past due	23,000	0
60 - 89 days past due	0	0
> 90 days past due	1,098,000	892,000
Total Past due	1,121,000	892,000
Current	88,968,000	72,625,000
Total loans, excluding covered loans	90,089,000	73,517,000
> 90 days past due and still accruing	0	0
Non Covered Loans | Real estate-commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 days past due	8,280,000	2,549,000
60 - 89 days past due	2,747,000	1,931,000
> 90 days past due	23,569,000	27,966,000
Total Past due	34,596,000	32,446,000
Current	1,459,373,000	1,384,562,000
Total loans, excluding covered loans	1,493,969,000	1,417,008,000
> 90 days past due and still accruing	0	0
Non Covered Loans | Real estate-residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans, excluding covered loans	352,830,000	318,210,000
Non Covered Loans | Real estate - residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 days past due	1,705,000	6,071,000
60 - 89 days past due	1,230,000	1,463,000
> 90 days past due	6,484,000	6,113,000
Total Past due	9,419,000	13,647,000
Current	343,411,000	304,563,000
Total loans, excluding covered loans	352,830,000	318,210,000
> 90 days past due and still accruing	0	0
Non Covered Loans | Installment
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 days past due	389,000	280,000
60 - 89 days past due	38,000	148,000
> 90 days past due	371,000	344,000
Total Past due	798,000	772,000
Current	48,475,000	56,038,000
Total loans, excluding covered loans	49,273,000	56,810,000
> 90 days past due and still accruing	0	0
Non Covered Loans | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 days past due	735,000	1,311,000
60 - 89 days past due	442,000	869,000
> 90 days past due	1,525,000	1,440,000
Total Past due	2,702,000	3,620,000
Current	371,137,000	363,880,000
Total loans, excluding covered loans	373,839,000	367,500,000
> 90 days past due and still accruing	0	0
Non Covered Loans | All other
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 days past due	424,000	386,000
60 - 89 days past due	111,000	168,000
> 90 days past due	351,000	708,000
Total Past due	886,000	1,262,000
Current	110,014,000	83,724,000
Total loans, excluding covered loans	110,900,000	84,986,000
> 90 days past due and still accruing	$ 265,000	$ 212,000