LOANS AND LEASES, Aging (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Aging of loan and lease portfolio [Abstract]
30-59 Days Past Due	$ 29,315	$ 37,336
60-89 Days Past Due	11,524	20,207
90 Plus Days Past Due	51,345	78,309
Total Past Due	92,184	135,852
Current	8,544,805	8,734,459
Total Outstanding	8,636,989	8,870,311
90 Plus Days Past Due still Accruing	1,210	3,434
Commercial and industrial segment [Member]
Aging of loan and lease portfolio [Abstract]
30-59 Days Past Due	3,531	5,571
60-89 Days Past Due	476	4,209
90 Plus Days Past Due	4,118	4,193
Total Past Due	8,125	13,973
Current	1,468,486	1,459,755
Total Outstanding	1,476,611	1,473,728
90 Plus Days Past Due still Accruing	414	12
Real estate segment [Member] | Consumer mortgages [Member]
Aging of loan and lease portfolio [Abstract]
30-59 Days Past Due	11,308	15,740
60-89 Days Past Due	3,643	6,485
90 Plus Days Past Due	13,821	14,569
Total Past Due	28,772	36,794
Current	1,845,103	1,908,396
Total Outstanding	1,873,875	1,945,190
90 Plus Days Past Due still Accruing	512	2,974
Real estate segment [Member] | Home equity [Member]
Aging of loan and lease portfolio [Abstract]
30-59 Days Past Due	1,337	1,837
60-89 Days Past Due	371	265
90 Plus Days Past Due	350	594
Total Past Due	2,058	2,696
Current	484,016	511,666
Total Outstanding	486,074	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	400	666
60-89 Days Past Due	287	54
90 Plus Days Past Due	3,946	719
Total Past Due	4,633	1,439
Current	251,563	238,048
Total Outstanding	256,196	239,487
90 Plus Days Past Due still Accruing	10	0
Real estate segment [Member] | Commercial and industrial-owner occupied [Member]
Aging of loan and lease portfolio [Abstract]
30-59 Days Past Due	2,629	2,199
60-89 Days Past Due	3,587	844
90 Plus Days Past Due	2,933	12,977
Total Past Due	9,149	16,020
Current	1,323,954	1,285,555
Total Outstanding	1,333,103	1,301,575
90 Plus Days Past Due still Accruing	19	0
Real estate segment [Member] | Construction, acquisition and development [Member]
Aging of loan and lease portfolio [Abstract]
30-59 Days Past Due	2,547	4,826
60-89 Days Past Due	2,472	4,955
90 Plus Days Past Due	14,790	33,584
Total Past Due	19,809	43,365
Current	715,999	864,997
Total Outstanding	735,808	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	4,673	3,778
60-89 Days Past Due	56	2,702
90 Plus Days Past Due	10,469	9,397
Total Past Due	15,198	15,877
Current	1,733,683	1,738,145
Total Outstanding	1,748,881	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	536	595
60-89 Days Past Due	379	303
90 Plus Days Past Due	473	697
Total Past Due	1,388	1,595
Current	103,496	104,686
Total Outstanding	104,884	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	2,354	2,124
60-89 Days Past Due	253	390
90 Plus Days Past Due	445	1,579
Total Past Due	3,052	4,093
Current	618,505	623,211
Total Outstanding	621,557	627,304
90 Plus Days Past Due still Accruing	$ 27	$ 149