ALLOWANCE FOR CREDIT LOSSES (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Changes in the allowance for credit losses [Roll Forward]
Balance at beginning of year	$ 196,913	$ 176,043	$ 132,793
Provision charged to expense	130,081	204,016	117,324
Recoveries	10,179	7,876	4,139
Loans and leases charged off	(142,055)	(191,022)	(78,213)
Balance at end of year	195,118	196,913	176,043
Commercial and industrial segment [Member]
Changes in the allowance for credit losses [Roll Forward]
Balance at beginning of year	22,479	21,154
Provision charged to expense	14,015	11,874
Recoveries	1,567	1,330
Loans and leases charged off	(17,337)	(11,879)
Balance at end of year	20,724	22,479
Real estate segment [Member] | Consumer mortgages [Member]
Changes in the allowance for credit losses [Roll Forward]
Balance at beginning of year	35,540	37,048
Provision charged to expense	10,064	13,324
Recoveries	1,111	1,448
Loans and leases charged off	(10,186)	(16,280)
Balance at end of year	36,529	35,540
Real estate segment [Member] | Home equity [Member]
Changes in the allowance for credit losses [Roll Forward]
Balance at beginning of year	7,305	7,218
Provision charged to expense	6,992	5,123
Recoveries	185	179
Loans and leases charged off	(5,852)	(5,215)
Balance at end of year	8,630	7,305
Real estate segment [Member] | Agricultural [Member]
Changes in the allowance for credit losses [Roll Forward]
Balance at beginning of year	4,997	4,192
Provision charged to expense	2,221	1,994
Recoveries	123	12
Loans and leases charged off	(3,420)	(1,201)
Balance at end of year	3,921	4,997
Real estate segment [Member] | Commercial and industrial-owner occupied [Member]
Changes in the allowance for credit losses [Roll Forward]
Balance at beginning of year	20,403	22,989
Provision charged to expense	11,435	6,215
Recoveries	393	399
Loans and leases charged off	(10,302)	(9,200)
Balance at end of year	21,929	20,403
Real estate segment [Member] | Construction, acquisition and development [Member]
Changes in the allowance for credit losses [Roll Forward]
Balance at beginning of year	59,048	46,193
Provision charged to expense	49,925	133,745
Recoveries	3,951	1,706
Loans and leases charged off	(67,362)	(122,596)
Balance at end of year	45,562	59,048
Real estate segment [Member] | Commercial [Member]
Changes in the allowance for credit losses [Roll Forward]
Balance at beginning of year	33,439	26,694
Provision charged to expense	22,396	19,984
Recoveries	1,045	845
Loans and leases charged off	(17,436)	(14,084)
Balance at end of year	39,444	33,439
Credit cards segment [Member]
Changes in the allowance for credit losses [Roll Forward]
Balance at beginning of year	4,126	3,481
Provision charged to expense	2,164	4,375
Recoveries	803	829
Loans and leases charged off	(3,072)	(4,559)
Balance at end of year	4,021	4,126
All other receivables [Member]
Changes in the allowance for credit losses [Roll Forward]
Balance at beginning of year	9,576	7,074
Provision charged to expense	10,869	7,382
Recoveries	1,001	1,128
Loans and leases charged off	(7,088)	(6,008)
Balance at end of year	$ 14,358	$ 9,576