ALLOWANCE FOR CREDIT LOSS (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended		12 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Changes in the allowance for credit losses [Roll Forward]
Balance at beginning of period	$ 195,118	$ 196,913	$ 196,913
Charge-offs	(50,726)	(90,003)	(142,055)
Recoveries	15,455	4,998	10,179
Provision	16,000	85,719	130,081
Balance at end of year	175,847	197,627	195,118
Commercial and industrial segment [Member]
Changes in the allowance for credit losses [Roll Forward]
Balance at beginning of period	20,724	22,479	22,479
Charge-offs	(5,854)	(14,365)	(17,337)
Recoveries	2,582	773	1,567
Provision	8,363	13,953	14,015
Balance at end of year	25,815	22,840	20,724
Real estate [Member] | Consumer mortgages [Member]
Changes in the allowance for credit losses [Roll Forward]
Balance at beginning of period	36,529	35,540	35,540
Charge-offs	(7,034)	(4,889)	(10,186)
Recoveries	761	363	1,111
Provision	4,175	6,031	10,064
Balance at end of year	34,431	37,045	36,529
Real estate [Member] | Home equity [Member]
Changes in the allowance for credit losses [Roll Forward]
Balance at beginning of period	8,630	7,305	7,305
Charge-offs	(1,387)	(2,473)	(5,852)
Recoveries	393	91	185
Provision	(300)	2,697	6,992
Balance at end of year	7,336	7,620	8,630
Real estate [Member] | Agricultural [Member]
Changes in the allowance for credit losses [Roll Forward]
Balance at beginning of period	3,921	4,997	4,997
Charge-offs	(482)	(965)	(3,420)
Recoveries	63	47	123
Provision	(243)	630	2,221
Balance at end of year	3,259	4,709	3,921
Real estate [Member] | Commercial and industrial-owner occupied [Member]
Changes in the allowance for credit losses [Roll Forward]
Balance at beginning of period	21,929	20,403	20,403
Charge-offs	(6,600)	(4,944)	(10,302)
Recoveries	1,865	194	393
Provision	165	8,991	11,435
Balance at end of year	17,359	24,644	21,929
Real estate [Member] | Construction, acquisition and development [Member]
Changes in the allowance for credit losses [Roll Forward]
Balance at beginning of period	45,562	59,048	59,048
Charge-offs	(20,954)	(49,126)	(67,362)
Recoveries	4,110	2,057	3,951
Provision	4,037	41,941	49,925
Balance at end of year	32,755	53,920	45,562
Real estate [Member] | Commercial Real Estate [Member]
Changes in the allowance for credit losses [Roll Forward]
Balance at beginning of period	39,444	33,439	33,439
Charge-offs	(6,069)	(6,111)	(17,436)
Recoveries	4,887	405	1,045
Provision	(1,096)	7,560	22,396
Balance at end of year	37,166	35,293	39,444
Credit cards segment [Member]
Changes in the allowance for credit losses [Roll Forward]
Balance at beginning of period	4,021	4,126	4,126
Charge-offs	(1,150)	(1,606)	(3,072)
Recoveries	239	494	803
Provision	49	473	2,164
Balance at end of year	3,159	3,487	4,021
All other receivables [Member]
Changes in the allowance for credit losses [Roll Forward]
Balance at beginning of period	14,358	9,576	9,576
Charge-offs	(1,196)	(5,524)	(7,088)
Recoveries	555	574	1,001
Provision	850	3,443	10,869
Balance at end of year	$ 14,567	$ 8,069	$ 14,358