FAIR VALUE ACCOUNTING AND MEASUREMENT (Non-recurring Basis) (Details) (USD $)	3 Months Ended			9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012	Sep. 30, 2013		Sep. 30, 2012	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans individually evaluated for impairment	$ 59,525,000		$ 58,747,000	$ 59,525,000		$ 58,747,000
Allowance for credit losses, write-downs	1,725,000		4,912,000	6,502,000		20,255,000
Impaired Financing Receivable, Related Allowance	6,720,000			6,720,000			8,338,000
Allowance individually evaluated for impairment	5,823,000		5,363,000	5,823,000		5,363,000
Loans collectively evaluated for impairment	3,215,911,000		3,154,776,000	3,215,911,000		3,154,776,000
Allowance collectively evaluated for impairment	70,834,000		73,420,000	70,834,000		73,420,000
Impaired Financing Receivable, with Related Allowance, Recorded Investment	75,292,000			75,292,000			91,852,000
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	79,941,000			79,941,000			98,232,000
Nonrecurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Classifed loans	107,000,000			107,000,000
Allowance for credit losses, write-downs				2,000,000
Impairment of real estate owned	191,000		1,300,000
With Specific Allowance Reserve , Individually Evaluated for Impairment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Financing Receivable, Related Allowance	5,824,000	[1]		5,824,000	[1]		5,725,000	[1]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	59,526,000	[1]		59,526,000	[1]		63,123,000	[1]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	61,931,000	[1]		61,931,000	[1]		66,012,000	[1]
Loans Without Specific Allowance Reserve, Collectively Evaluated for Impairment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Financing Receivable, Related Allowance	896,000	[2]		896,000	[2]		2,613,000	[2]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	15,766,000	[2]		15,766,000	[2]		28,729,000	[2]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	18,010,000	[2]		18,010,000	[2]		32,220,000	[2]
Servicing Contracts for Third Parties [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Serviced For Others	1,086,000,000		850,000,000	1,086,000,000		850,000,000	918,000,000
Mortgage Servicing Rights [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Valuation adjustments in the period	400,000		0	1,000,000		0
Custodial Accounts	$ 3,600,000		$ 7,300,000	$ 3,600,000		$ 7,300,000	$ 4,700,000

[1] Loans with a specific allowance reserve have been individually evaluated for impairment using either a discounted cash flow analysis or, for collateral dependent loans, current appraisals to establish realizable value. These analyses may identify a specific impairment amount needed or may conclude that no reserve is needed. Any specific impairment that is identified is included in the category’s Related Allowance column.

[2] Loans without a specific allowance reserve have not been individually evaluated for impairment, but have been included in pools of homogeneous loans for evaluation of related allowance reserves.