LOANS AND LEASES, Aging (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011
Aging of loan and lease portfolio [Abstract]
30-59 Days Past Due	$ 36,418	$ 37,336
60-89 Days Past Due	11,272	20,207
90 Plus Days Past Due	57,711	78,309
Total Past Due	105,401	135,852
Current	8,632,522	8,734,459
Total Outstanding	8,737,923	8,870,311
90 Plus Days Past Due still Accruing	1,698	3,434	4,829
Commercial and industrial segment [Member]
Aging of loan and lease portfolio [Abstract]
30-59 Days Past Due	3,831	5,571
60-89 Days Past Due	1,511	4,209
90 Plus Days Past Due	3,392	4,193
Total Past Due	8,734	13,973
Current	1,432,993	1,459,755
Total Outstanding	1,441,727	1,473,728
90 Plus Days Past Due still Accruing	10	12
Real estate segment [Member] | Consumer mortgages [Member]
Aging of loan and lease portfolio [Abstract]
30-59 Days Past Due	10,482	15,740
60-89 Days Past Due	4,776	6,485
90 Plus Days Past Due	17,830	14,569
Total Past Due	33,088	36,794
Current	1,904,909	1,908,396
Total Outstanding	1,937,997	1,945,190
90 Plus Days Past Due still Accruing	1,314	2,974
Real estate segment [Member] | Home equity [Member]
Aging of loan and lease portfolio [Abstract]
30-59 Days Past Due	1,832	1,837
60-89 Days Past Due	769	265
90 Plus Days Past Due	288	594
Total Past Due	2,889	2,696
Current	498,442	511,666
Total Outstanding	501,331	514,362
90 Plus Days Past Due still Accruing	0	0
Real estate segment [Member] | Agricultural [Member]
Aging of loan and lease portfolio [Abstract]
30-59 Days Past Due	638	666
60-89 Days Past Due	25	54
90 Plus Days Past Due	1,518	719
Total Past Due	2,181	1,439
Current	254,502	238,048
Total Outstanding	256,683	239,487
90 Plus Days Past Due still Accruing	0	0
Real estate segment [Member] | Commercial and industrial-owner occupied [Member]
Aging of loan and lease portfolio [Abstract]
30-59 Days Past Due	2,493	2,199
60-89 Days Past Due	1,601	844
90 Plus Days Past Due	8,603	12,977
Total Past Due	12,697	16,020
Current	1,274,845	1,285,555
Total Outstanding	1,287,542	1,301,575
90 Plus Days Past Due still Accruing	0	0
Real estate segment [Member] | Construction, acquisition and development [Member]
Aging of loan and lease portfolio [Abstract]
30-59 Days Past Due	9,860	4,826
60-89 Days Past Due	331	4,955
90 Plus Days Past Due	16,142	33,584
Total Past Due	26,333	43,365
Current	831,777	864,997
Total Outstanding	858,110	908,362
90 Plus Days Past Due still Accruing	0	0
Real estate segment [Member] | Commercial [Member]
Aging of loan and lease portfolio [Abstract]
30-59 Days Past Due	5,165	3,778
60-89 Days Past Due	1,540	2,702
90 Plus Days Past Due	8,979	9,397
Total Past Due	15,684	15,877
Current	1,726,317	1,738,145
Total Outstanding	1,742,001	1,754,022
90 Plus Days Past Due still Accruing	0	0
Credit cards segment [Member]
Aging of loan and lease portfolio [Abstract]
30-59 Days Past Due	377	595
60-89 Days Past Due	360	303
90 Plus Days Past Due	587	697
Total Past Due	1,324	1,595
Current	99,203	104,686
Total Outstanding	100,527	106,281
90 Plus Days Past Due still Accruing	228	299
All other receivables [Member]
Aging of loan and lease portfolio [Abstract]
30-59 Days Past Due	1,740	2,124
60-89 Days Past Due	359	390
90 Plus Days Past Due	372	1,579
Total Past Due	2,471	4,093
Current	609,534	623,211
Total Outstanding	612,005	627,304
90 Plus Days Past Due still Accruing	$ 146	$ 149