FAIR VALUE (Details) (USD $)	3 Months Ended		9 Months Ended				9 Months Ended								3 Months Ended				9 Months Ended				3 Months Ended		9 Months Ended
	Sep. 30, 2011		Sep. 30, 2011		Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2012 Pooled Trust Preferred Securities [Member]	Sep. 30, 2012 Impaired Loans [Member]	Sep. 30, 2012 Other Real Estate Owned [Member]	Sep. 30, 2012 Mortgage Servicing Rights [Member]	Sep. 30, 2012 Carrying [Member]	Dec. 31, 2011 Carrying [Member]	Sep. 30, 2012 Fair Value Disclosure [Member]	Dec. 31, 2011 Fair Value Disclosure [Member]	Sep. 30, 2012 Pooled Trust Preferred Securities [Member]		Sep. 30, 2011 Pooled Trust Preferred Securities [Member]		Sep. 30, 2012 Pooled Trust Preferred Securities [Member]		Sep. 30, 2011 Pooled Trust Preferred Securities [Member]		Sep. 30, 2011 Commitments to Originate Real Estate Loans for Sale [Member]		Sep. 30, 2011 Commitments to Originate Real Estate Loans for Sale [Member]		Sep. 30, 2012 Recurring [Member]	Dec. 31, 2011 Recurring [Member]	Sep. 30, 2012 Recurring [Member] Level 1 [Member]	Dec. 31, 2011 Recurring [Member] Level 1 [Member]	Sep. 30, 2012 Recurring [Member] Level 2 [Member]	Dec. 31, 2011 Recurring [Member] Level 2 [Member]	Sep. 30, 2012 Recurring [Member] Level 3 [Member]	Dec. 31, 2011 Recurring [Member] Level 3 [Member]	Sep. 30, 2012 Nonrecurring [Member]	Dec. 31, 2011 Nonrecurring [Member]	Sep. 30, 2012 Nonrecurring [Member] Level 1 [Member]	Dec. 31, 2011 Nonrecurring [Member] Level 1 [Member]	Sep. 30, 2012 Nonrecurring [Member] Level 2 [Member]	Dec. 31, 2011 Nonrecurring [Member] Level 2 [Member]	Sep. 30, 2012 Nonrecurring [Member] Level 3 [Member]	Dec. 31, 2011 Nonrecurring [Member] Level 3 [Member]
Available-for-sale investment securities:
U.S. Treasury and agency securities																											$ 1,085,753,000	$ 520,548,000	$ 896,521,000	$ 311,958,000	$ 189,232,000	$ 208,590,000	$ 0	$ 0
Obligations of state and political subdivisions																											707,321,000	573,012,000	0	0	707,321,000	573,012,000	0	0
Government agency mortgage-backed securities																											288,295,000	331,379,000	0	0	288,295,000	331,379,000	0	0
Pooled trust preferred securities																											50,837,000	43,846,000	0	0	0	0	50,837,000	43,846,000
Government agency collateralized mortgage obligations																											36,975,000	46,943,000	0	0	36,975,000	46,943,000	0	0
Corporate debt securities																											25,549,000	22,855,000	0	0	25,549,000	22,855,000	0	0
Marketable equity securities																											374,000	390,000	374,000	390,000	0	0	0	0
Total available-for-sale investment securities					2,195,104,000	1,538,973,000																					2,195,104,000	1,538,973,000	896,895,000	312,348,000	1,247,372,000	1,182,779,000	50,837,000	43,846,000
Mortgage loans held for sale																											113,000	532,000	0	0	113,000	532,000	0	0
Total																											2,195,217,000	1,539,505,000	896,895,000	312,348,000	1,247,485,000	1,183,311,000	50,837,000	43,846,000
Unpaid principal value of mortgage loans held for sale					113,000
Assets and Liabilities Measured on Nonrecurring Basis [Abstract]
Impaired loans																																			294,000	4,118,000	0	0	0	0	294,000	4,118,000
Other real estate owned																																			3,384,000	2,682,000	0	0	0	0	3,384,000	2,682,000
Mortgage servicing rights																																			1,178,000	1,747,000	0	0	0	0	1,178,000	1,747,000
Total							50,837,000	294,000	3,384,000	1,178,000																									4,856,000	8,547,000	0	0	0	0	4,856,000	8,547,000
Impaired Loans Valuation Allowance					430,000
Discount on appraisal value of foreclosed real estate, minimum (in hundredths)					3.00%
Discount on appraisal value of foreclosed real estate, maximum (in hundredths)					64.00%
Level 3 Assets Measured at Fair Value on a Recurring Basis [Abstract]
Beginning balance	49,114,000		42,051,000												48,786,000		48,972,000		43,846,000		41,993,000		142,000		58,000
Total gains (losses) included in earnings	(119,000)	[1],[2]	(187,000)	[1],[2]											32,000	[1],[2]	23,000	[1],[2]	176,000	[1],[2]	71,000	[1],[2]	(142,000)	[1],[2]	(258,000)	[1],[2]
Total gains included in other comprehensive income	(1,627,000)	[3]	6,052,000	[3]											2,769,000	[3]	(1,627,000)	[3]	11,136,000	[3]	6,052,000	[3]	0	[3]	0	[3]
Principal reductions	(345,000)		(1,093,000)												(750,000)		(345,000)		(4,321,000)		(1,093,000)		0		0
Commitments to originate real estate loans held for sale, net			200,000																0		0				200,000
Ending balance	47,023,000		47,023,000												50,837,000		47,023,000		50,837,000		47,023,000		0		0
Financial assets:
Net loans											3,812,457,000	3,471,025,000	3,835,406,000	3,491,729,000
Financial liabilities:
Deposits											5,708,629,000	4,795,245,000	5,716,925,000	4,810,856,000
Borrowings											728,116,000	728,281,000	827,739,000	828,018,000
Subordinated debt held by unconsolidated subsidiary trusts											102,067,000	102,048,000	93,154,000	73,211,000
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Assets, Fair Value Disclosure							$ 50,837,000	$ 294,000	$ 3,384,000	$ 1,178,000																									$ 4,856,000	$ 8,547,000	$ 0	$ 0	$ 0	$ 0	$ 4,856,000	$ 8,547,000
Pooled Trust Preferred Securities, Valuation Techniques							Consensus pricing
Impaired Loans, Valuation Techniques								Fair value of collateral
Other Real Estate Owned, Valuation Techniques									Fair value of collateral
Mortgage Servicing Rights, Valuation Techniques										Discounted cash flow
Significant Unobservable Inputs, Inputs Description							Weighting of offered quotes	Discount	Discount	Weighted average constant prepayment rate / Weighted average discount rate / Adequate compensation
Significant Unobservable Input Range, Minimum (in hundredths)							60.30%	25.00%	3.00%
Significant Unobservable Input Range, Maximum (in hundredths)							85.60%	25.00%	64.00%
Significant Unobservable Input Range, Weighted Average (in hundredths)							77.80%	25.00%	27.00%
Constant Prepayment Input Range Minimum (in hundredths)										20.50%
Constant Prepayment Input Range Maximum (in hundredths)										36.00%
Constant Prepayment Input Range Weighted Average (in hundredths)										31.10%
Weighted average discount rate Input Range Minimum (in hundredths)										2.40%
Weighted average discount rate Input Range Maximum (in hundredths)										3.17%
Weighted average discount rate Input Range Weighted Average (in hundredths)										2.98%
Adequate Compensation Input Range										$7/loan

[1] Amounts included in earnings associated with the commitments to originate real estate loans for sale are reported as a component of other banking service fees.

[2] Amounts included in earnings associated with the pooled trust preferred securities relate to accretion of related discount and are reported in interest and dividends on taxable investments.

[3] Amounts included in other comprehensive income associated with the pooled trust preferred securities are relate to changes in unrealized loss and are reported as a component of unrealized gains on securities in the Statement of Comprehensive Income.