LOANS AND LEASES (Loan And Lease Portfolio, Net Of Unearned Income, By Segment, Class And Internally Assigned Grade) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total	$ 10,811,991	$ 10,372,778
Alabama and Florida Panhandle [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total	1,299,388
Arkansas [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total	1,329,883
Mississippi [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total	3,576,862
Missouri [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total	468,148
Texas [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total	1,781,610
Other Geographical Areas [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total	211,245
Pass [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total	10,528,334	10,093,619
Special Mention [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total	4,824
Substandard [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total	240,214	227,141
Doubtful [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total	382	626
Impaired [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total	38,237	51,392
Commercial And Industrial [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total	1,612,295	1,747,774
Credit Cards [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total	109,656	112,165
Agricultural [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total		259,360
Agricultural [Member] | Pass [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total		250,579
Agricultural [Member] | Substandard [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total		7,909
Agricultural [Member] | Impaired [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total		872
Commercial And Industrial-Owner Occupied [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total		1,617,429
Commercial And Industrial-Owner Occupied [Member] | Pass [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total		1,554,984
Commercial And Industrial-Owner Occupied [Member] | Substandard [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total		50,304
Commercial And Industrial-Owner Occupied [Member] | Impaired [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total		12,141
All Other [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total	$ 412,619	441,003
All Other [Member] | Pass [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total		433,333
All Other [Member] | Substandard [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total		7,465
All Other [Member] | Doubtful [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total		102
All Other [Member] | Impaired [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total		103
Construction, Acquisition And Development [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total		945,045
Construction, Acquisition And Development [Member] | Pass [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total		920,372
Construction, Acquisition And Development [Member] | Substandard [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total		17,090
Construction, Acquisition And Development [Member] | Impaired [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total		7,583
Commercial Real Estate [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total		2,188,048
Commercial Real Estate [Member] | Pass [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total		2,124,448
Commercial Real Estate [Member] | Substandard [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total		45,658
Commercial Real Estate [Member] | Doubtful [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total		161
Commercial Real Estate [Member] | Impaired [Member]
Loan and lease portfolio, net of unearned income, by grade [Abstract]
Total		$ 17,781