LOANS AND LEASES (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010
Loans and leases, gross [Abstract]
Commercial and industrial	$ 1,540,048	$ 1,505,471	$ 1,499,152
Real estate
Consumer mortgages	1,971,499	1,951,563	1,981,475
Home equity	531,787	543,272	555,281
Agricultural	255,310	252,292	260,489
Commercial and industrial-owner occupied	1,366,734	1,331,473	1,407,704
Construction, acquisition and development	1,060,675	1,174,743	1,419,303
Commercial	1,764,648	1,816,951	1,794,644
Credit cards	101,955	106,345	102,784
All other	663,223	694,241	670,791
Total	9,255,879	9,376,351	9,691,623
Loans and leases, net of unearned income [Abstract]
Commercial and industrial	1,526,686
Real Estate [Abstract]
Consumer mortgages	1,971,499
Home equity	531,787
Agricultural	255,310
Commercial and industrial-owner occupied	1,366,734
Construction, acquisition and development	1,060,675
Commercial	1,764,648
Credit cards	101,955
All other	635,259
Total	9,214,553	9,333,107
Loan concentrations [Abstract]
Maximum percentage of loan concentrations (in hundredths)	10.00%
Alabama and Florida Panhandle [Member]
Loans and leases, net of unearned income [Abstract]
Commercial and industrial	63,477
Real Estate [Abstract]
Consumer mortgages	114,266
Home equity	64,043
Agricultural	7,338
Commercial and industrial-owner occupied	125,567
Construction, acquisition and development	133,335
Commercial	195,722
Credit cards	0
All other	14,936
Total	718,684
Arkansas [Member]
Loans and leases, net of unearned income [Abstract]
Commercial and industrial	219,533
Real Estate [Abstract]
Consumer mortgages	273,338
Home equity	43,224
Agricultural	73,285
Commercial and industrial-owner occupied	175,098
Construction, acquisition and development	86,795
Commercial	340,963
Credit cards	0
All other	42,680
Total	1,254,916
Mississippi [Member]
Loans and leases, net of unearned income [Abstract]
Commercial and industrial	322,786
Real Estate [Abstract]
Consumer mortgages	779,838
Home equity	178,305
Agricultural	75,142
Commercial and industrial-owner occupied	472,765
Construction, acquisition and development	273,624
Commercial	344,926
Credit cards	0
All other	79,088
Total	2,526,474
Missouri [Member]
Loans and leases, net of unearned income [Abstract]
Commercial and industrial	85,073
Real Estate [Abstract]
Consumer mortgages	66,163
Home equity	29,297
Agricultural	5,642
Commercial and industrial-owner occupied	74,684
Construction, acquisition and development	88,309
Commercial	241,209
Credit cards	0
All other	1,409
Total	591,786
Greater Memphis Area [Member]
Loans and leases, net of unearned income [Abstract]
Commercial and industrial	24,045
Real Estate [Abstract]
Consumer mortgages	87,596
Home equity	73,790
Agricultural	16,248
Commercial and industrial-owner occupied	109,132
Construction, acquisition and development	128,537
Commercial	132,670
Credit cards	0
All other	48,596
Total	620,614
Northeast Tennessee [Member]
Loans and leases, net of unearned income [Abstract]
Commercial and industrial	84,544
Real Estate [Abstract]
Consumer mortgages	164,453
Home equity	79,307
Agricultural	13,629
Commercial and industrial-owner occupied	101,806
Construction, acquisition and development	130,962
Commercial	105,507
Credit cards	0
All other	28,516
Total	708,724
Texas and Louisiana [Member]
Loans and leases, net of unearned income [Abstract]
Commercial and industrial	274,812
Real Estate [Abstract]
Consumer mortgages	412,493
Home equity	62,617
Agricultural	58,370
Commercial and industrial-owner occupied	246,369
Construction, acquisition and development	208,406
Commercial	354,065
Credit cards	0
All other	29,521
Total	1,646,653
Other Geographical Areas [Member]
Loans and leases, net of unearned income [Abstract]
Commercial and industrial	452,416
Real Estate [Abstract]
Consumer mortgages	73,352
Home equity	1,204
Agricultural	5,656
Commercial and industrial-owner occupied	61,313
Construction, acquisition and development	10,707
Commercial	49,586
Credit cards	101,955
All other	390,513
Total	$ 1,146,702