ALLOWANCE FOR CREDIT LOSSES, by Segment, Class and Impairment Status (Details) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010	Dec. 31, 2009
Financing Receivable, Impaired [Line Items]
Recorded balance of impaired loans	$ 303,657	$ 273,405
Allowance for impaired loans and leases	46,810	40,719
Allowance for all other loans and leases	150,817	156,194
Total allowance	197,627	196,913	200,744	176,043
Commercial and industrial segment [Member]
Financing Receivable, Impaired [Line Items]
Recorded balance of impaired loans	5,985	2,136
Allowance for impaired loans and leases	456	125
Allowance for all other loans and leases	22,384	22,354
Total allowance	22,840	22,479	22,518	21,154
Consumer mortgage [Member] | Real estate segment [Member]
Financing Receivable, Impaired [Line Items]
Recorded balance of impaired loans	23,743	28,223
Allowance for impaired loans and leases	2,278	4,226
Allowance for all other loans and leases	34,767	31,314
Total allowance	37,045	35,540	32,595	37,048
Home equity [Member] | Real estate segment [Member]
Financing Receivable, Impaired [Line Items]
Recorded balance of impaired loans	670	851
Allowance for impaired loans and leases	39	41
Allowance for all other loans and leases	7,581	7,264
Total allowance	7,620	7,305	6,779	7,218
Agricultural [Member] | Real estate segment [Member]
Financing Receivable, Impaired [Line Items]
Recorded balance of impaired loans	7,316	4,295
Allowance for impaired loans and leases	1,729	544
Allowance for all other loans and leases	2,980	4,453
Total allowance	4,709	4,997	3,767	4,192
Commercial and industrial-owner occupied [Member] | Real estate segment [Member]
Financing Receivable, Impaired [Line Items]
Recorded balance of impaired loans	21,190	16,073
Allowance for impaired loans and leases	3,151	1,361
Allowance for all other loans and leases	21,493	19,042
Total allowance	24,644	20,403	22,533	22,989
Construction, acquisition and development [Member] | Real estate segment [Member]
Financing Receivable, Impaired [Line Items]
Recorded balance of impaired loans	197,031	184,918
Allowance for impaired loans and leases	27,721	29,195
Allowance for all other loans and leases	26,199	29,853
Total allowance	53,920	59,048	68,305	46,193
Commercial [Member] | Real estate segment [Member]
Financing Receivable, Impaired [Line Items]
Recorded balance of impaired loans	45,853	36,207
Allowance for impaired loans and leases	10,642	5,227
Allowance for all other loans and leases	24,651	28,212
Total allowance	35,293	33,439	28,643	26,694
Credit cards segment [Member]
Financing Receivable, Impaired [Line Items]
Allowance for all other loans and leases	3,487	4,126
Total allowance	3,487	4,126	3,311	3,481
All other receivables [Member]
Financing Receivable, Impaired [Line Items]
Recorded balance of impaired loans	1,869	702
Allowance for impaired loans and leases	794	0
Allowance for all other loans and leases	7,275	9,576
Total allowance	$ 8,069	$ 9,576	$ 12,293	$ 7,074