LOANS AND LEASES, Non-performing and Nonaccrual Loans and Leases (Details) (USD $)	9 Months Ended	12 Months Ended
	Sep. 30, 2011	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Non-performing loans and leases [Abstract]
Non-accrual loans and leases		$ 276,798,000	$ 347,499,000
Loans and leases 90 days or more past due, still accruing		3,434,000	8,500,000
Restructured loans and leases still accruing		42,018,000	38,376,000
Total non-performing loans and leases		322,250,000	394,375,000
Days past due of principal or interest at which loans and leases may be placed in non-accrual status (in days)	90D	90D
Nonaccrual loans and leases [Abstract]
Non-accrual loans and leases		276,798,000	347,499,000
Total interest earned on NPLs		12,600,000	11,200,000	4,100,000
Gross interest income which would have been recorded for NPLs		18,700,000	21,700,000	8,400,000
Commercial and industrial segment [Member]
Non-performing loans and leases [Abstract]
Non-accrual loans and leases		12,260,000	13,075,000
Loans and leases 90 days or more past due, still accruing		12,000	675,000
Nonaccrual loans and leases [Abstract]
Non-accrual loans and leases		12,260,000	13,075,000
Real estate segment [Member] | Consumer mortgages [Member]
Non-performing loans and leases [Abstract]
Non-accrual loans and leases		47,878,000	34,021,000
Loans and leases 90 days or more past due, still accruing		2,974,000	6,521,000
Nonaccrual loans and leases [Abstract]
Non-accrual loans and leases		47,878,000	34,021,000
Real estate segment [Member] | Home equity [Member]
Non-performing loans and leases [Abstract]
Non-accrual loans and leases		2,036,000	811,000
Loans and leases 90 days or more past due, still accruing		0	173,000
Nonaccrual loans and leases [Abstract]
Non-accrual loans and leases		2,036,000	811,000
Real estate segment [Member] | Agricultural [Member]
Non-performing loans and leases [Abstract]
Non-accrual loans and leases		4,179,000	7,589,000
Loans and leases 90 days or more past due, still accruing		0	123,000
Nonaccrual loans and leases [Abstract]
Non-accrual loans and leases		4,179,000	7,589,000
Real estate segment [Member] | Commercial and industrial-owner occupied [Member]
Non-performing loans and leases [Abstract]
Non-accrual loans and leases		33,112,000	20,338,000
Loans and leases 90 days or more past due, still accruing		0	20,000
Nonaccrual loans and leases [Abstract]
Non-accrual loans and leases		33,112,000	20,338,000
Real estate segment [Member] | Construction, acquisition and development [Member]
Non-performing loans and leases [Abstract]
Non-accrual loans and leases		133,110,000	211,547,000
Loans and leases 90 days or more past due, still accruing		0	197,000
Nonaccrual loans and leases [Abstract]
Non-accrual loans and leases		133,110,000	211,547,000
Real estate segment [Member] | Commercial [Member]
Non-performing loans and leases [Abstract]
Non-accrual loans and leases		40,616,000	57,766,000
Loans and leases 90 days or more past due, still accruing		0	0
Nonaccrual loans and leases [Abstract]
Non-accrual loans and leases		40,616,000	57,766,000
Credit cards segment [Member]
Non-performing loans and leases [Abstract]
Non-accrual loans and leases		594,000	720,000
Loans and leases 90 days or more past due, still accruing		299,000	330,000
Nonaccrual loans and leases [Abstract]
Non-accrual loans and leases		594,000	720,000
All other receivables [Member]
Non-performing loans and leases [Abstract]
Non-accrual loans and leases		3,013,000	1,632,000
Loans and leases 90 days or more past due, still accruing		149,000	461,000
Nonaccrual loans and leases [Abstract]
Non-accrual loans and leases		$ 3,013,000	$ 1,632,000