LOANS AND LEASES, Aging (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012
Aging of loan and lease portfolio [Abstract]
30-59 Days Past Due	$ 28,279	$ 29,315
60-89 Days Past Due	7,584	11,524
90 Plus Days Past Due	44,294	51,345
Total Past Due	80,157	92,184
Current	8,598,557	8,544,805
Total	8,678,714	8,636,989
90 Plus Days Past Due still Accruing	1,440	1,210	1,632
Commercial and industrial segment [Member]
Aging of loan and lease portfolio [Abstract]
30-59 Days Past Due	1,482	3,531
60-89 Days Past Due	144	476
90 Plus Days Past Due	1,994	4,118
Total Past Due	3,620	8,125
Current	1,549,142	1,468,486
Total	1,552,762	1,476,611
90 Plus Days Past Due still Accruing		414
Real estate segment [Member] | Consumer mortgages [Member]
Aging of loan and lease portfolio [Abstract]
30-59 Days Past Due	12,808	11,308
60-89 Days Past Due	3,750	3,643
90 Plus Days Past Due	13,210	13,821
Total Past Due	29,768	28,772
Current	1,850,570	1,845,103
Total	1,880,338	1,873,875
90 Plus Days Past Due still Accruing	1,107	512
Real estate segment [Member] | Home equity [Member]
Aging of loan and lease portfolio [Abstract]
30-59 Days Past Due	1,062	1,337
60-89 Days Past Due	329	371
90 Plus Days Past Due	1,059	350
Total Past Due	2,450	2,058
Current	479,618	484,016
Total	482,068	486,074
Real estate segment [Member] | Agricultural [Member]
Aging of loan and lease portfolio [Abstract]
30-59 Days Past Due	550	400
60-89 Days Past Due	135	287
90 Plus Days Past Due	3,255	3,946
Total Past Due	3,940	4,633
Current	233,974	251,563
Total	237,914	256,196
90 Plus Days Past Due still Accruing		10
Real estate segment [Member] | Commercial and industrial-owner occupied [Member]
Aging of loan and lease portfolio [Abstract]
30-59 Days Past Due	2,337	2,629
60-89 Days Past Due	299	3,587
90 Plus Days Past Due	1,753	2,933
Total Past Due	4,389	9,149
Current	1,371,322	1,323,954
Total	1,375,711	1,333,103
90 Plus Days Past Due still Accruing		19
Real estate segment [Member] | Construction, acquisition and development [Member]
Aging of loan and lease portfolio [Abstract]
30-59 Days Past Due	2,458	2,547
60-89 Days Past Due	251	2,472
90 Plus Days Past Due	12,651	14,790
Total Past Due	15,360	19,809
Current	694,139	715,999
Total	709,499	735,808
Real estate segment [Member] | Commercial real estate [Member]
Aging of loan and lease portfolio [Abstract]
30-59 Days Past Due	5,582	4,673
60-89 Days Past Due	2,055	56
90 Plus Days Past Due	9,334	10,469
Total Past Due	16,971	15,198
Current	1,737,870	1,733,683
Total	1,754,841	1,748,881
90 Plus Days Past Due still Accruing	120
Credit cards segment [Member]
Aging of loan and lease portfolio [Abstract]
30-59 Days Past Due	466	536
60-89 Days Past Due	311	379
90 Plus Days Past Due	425	473
Total Past Due	1,202	1,388
Current	102,049	103,496
Total	103,251	104,884
90 Plus Days Past Due still Accruing	213	228
All other [Member]
Aging of loan and lease portfolio [Abstract]
30-59 Days Past Due	1,534	2,354
60-89 Days Past Due	310	253
90 Plus Days Past Due	613	445
Total Past Due	2,457	3,052
Current	579,873	618,505
Total	582,330	621,557
90 Plus Days Past Due still Accruing		$ 27