LOANS AND ALLOWANCE FOR LOAN LOSSES (Summary of Aging of the Loan Portfolio by Class) (Details) - USD ($) $ in Thousands	Mar. 31, 2016		Dec. 31, 2015		Mar. 31, 2015
Summary of aging of the loan portfolio, by class
Nonaccrual	$ 13,092		$ 11,936
Current	5,662,251		5,542,840
Total loans held for investment, net	5,780,502	[1]	5,671,462	[1]	$ 5,387,755
30 to 59 Days Past Due [Member]
Summary of aging of the loan portfolio, by class
Past Due	23,463		27,787
60 to 89 Days Past Due [Member]
Summary of aging of the loan portfolio, by class
Past Due	5,868		9,333
Greater Than 90 Days and still Accruing [Member]
Summary of aging of the loan portfolio, by class
Past Due	5,723		5,829
Purchased Impaired [Member]
Summary of aging of the loan portfolio, by class
Past Due	70,105		73,737
Current	61,827		64,455
Total loans held for investment, net	70,105		73,737		91,346
Purchased Impaired [Member] | Greater Than 90 Days and still Accruing [Member]
Summary of aging of the loan portfolio, by class
Past Due	3,502		4,257
Construction and Land Development [Member]
Summary of aging of the loan portfolio, by class
Nonaccrual	2,156		2,113
Current	765,461		737,958
Total loans held for investment, net	776,698		749,720		657,581
Construction and Land Development [Member] | 30 to 59 Days Past Due [Member]
Summary of aging of the loan portfolio, by class
Past Due	2,676		3,155
Construction and Land Development [Member] | 60 to 89 Days Past Due [Member]
Summary of aging of the loan portfolio, by class
Past Due	724		380
Construction and Land Development [Member] | Greater Than 90 Days and still Accruing [Member]
Summary of aging of the loan portfolio, by class
Past Due	544		128
Construction and Land Development [Member] | Purchased Impaired [Member]
Summary of aging of the loan portfolio, by class
Past Due	5,137		5,986
Current	4,544		5,376
Total loans held for investment, net	5,137		5,986		9,529
Construction and Land Development [Member] | Purchased Impaired [Member] | Greater Than 90 Days and still Accruing [Member]
Summary of aging of the loan portfolio, by class
Past Due	239		241
Commercial Real Estate - Owner Occupied [Member]
Summary of aging of the loan portfolio, by class
Nonaccrual	2,816		3,904
Current	816,180		826,859
Total loans held for investment, net	849,202		860,086		898,222
Commercial Real Estate - Owner Occupied [Member] | 30 to 59 Days Past Due [Member]
Summary of aging of the loan portfolio, by class
Past Due	1,787		1,714
Commercial Real Estate - Owner Occupied [Member] | 60 to 89 Days Past Due [Member]
Summary of aging of the loan portfolio, by class
Past Due	963		118
Commercial Real Estate - Owner Occupied [Member] | Greater Than 90 Days and still Accruing [Member]
Summary of aging of the loan portfolio, by class
Past Due	196		103
Commercial Real Estate - Owner Occupied [Member] | Purchased Impaired [Member]
Summary of aging of the loan portfolio, by class
Past Due	27,260		27,388
Current	24,434		24,837
Total loans held for investment, net	27,260		27,388		31,004
Commercial Real Estate - Owner Occupied [Member] | Purchased Impaired [Member] | Greater Than 90 Days and still Accruing [Member]
Summary of aging of the loan portfolio, by class
Past Due	1,425		1,412
Commercial Real Estate - Non-Owner Occupied [Member]
Summary of aging of the loan portfolio, by class
Nonaccrual			100
Current	1,281,592		1,255,367
Total loans held for investment, net	1,296,251		1,270,480		1,180,464
Commercial Real Estate - Non-Owner Occupied [Member] | 30 to 59 Days Past Due [Member]
Summary of aging of the loan portfolio, by class
Past Due	24		771
Commercial Real Estate - Non-Owner Occupied [Member] | 60 to 89 Days Past Due [Member]
Summary of aging of the loan portfolio, by class
Past Due	276
Commercial Real Estate - Non-Owner Occupied [Member] | Greater Than 90 Days and still Accruing [Member]
Summary of aging of the loan portfolio, by class
Past Due	723		723
Commercial Real Estate - Non-Owner Occupied [Member] | Purchased Impaired [Member]
Summary of aging of the loan portfolio, by class
Past Due	13,636		13,519
Current	12,686		12,562
Total loans held for investment, net	13,636		13,519		16,648
Commercial Real Estate - Non-Owner Occupied [Member] | Purchased Impaired [Member] | Greater Than 90 Days and still Accruing [Member]
Summary of aging of the loan portfolio, by class
Past Due	205		202
Multifamily Real Estate [Member]
Summary of aging of the loan portfolio, by class
Current	320,983		320,701
Total loans held for investment, net	323,270		322,528		298,651
Multifamily Real Estate [Member] | 30 to 59 Days Past Due [Member]
Summary of aging of the loan portfolio, by class
Past Due	155
Multifamily Real Estate [Member] | Greater Than 90 Days and still Accruing [Member]
Summary of aging of the loan portfolio, by class
Past Due			272
Multifamily Real Estate [Member] | Purchased Impaired [Member]
Summary of aging of the loan portfolio, by class
Past Due	2,132		1,555
Current	2,132		1,555
Total loans held for investment, net	2,132		1,555		3,021
Commercial & Industrial [Member]
Summary of aging of the loan portfolio, by class
Nonaccrual	810		429
Current	449,136		431,916
Total loans held for investment, net	453,208		435,365		409,867
Commercial & Industrial [Member] | 30 to 59 Days Past Due [Member]
Summary of aging of the loan portfolio, by class
Past Due	985		1,056
Commercial & Industrial [Member] | 60 to 89 Days Past Due [Member]
Summary of aging of the loan portfolio, by class
Past Due	284		27
Commercial & Industrial [Member] | Greater Than 90 Days and still Accruing [Member]
Summary of aging of the loan portfolio, by class
Past Due	422		124
Commercial & Industrial [Member] | Purchased Impaired [Member]
Summary of aging of the loan portfolio, by class
Past Due	1,571		1,813
Current	1,336		1,583
Total loans held for investment, net	1,571		1,813		3,251
Commercial & Industrial [Member] | Purchased Impaired [Member] | Greater Than 90 Days and still Accruing [Member]
Summary of aging of the loan portfolio, by class
Past Due	39		21
Residential 1-4 Family [Member]
Summary of aging of the loan portfolio, by class
Nonaccrual	5,696		3,563
Current	937,408		928,312
Total loans held for investment, net	978,478		978,469		970,928
Residential 1-4 Family [Member] | 30 to 59 Days Past Due [Member]
Summary of aging of the loan portfolio, by class
Past Due	13,711		15,023
Residential 1-4 Family [Member] | 60 to 89 Days Past Due [Member]
Summary of aging of the loan portfolio, by class
Past Due	1,111		6,774
Residential 1-4 Family [Member] | Greater Than 90 Days and still Accruing [Member]
Summary of aging of the loan portfolio, by class
Past Due	2,247		3,638
Residential 1-4 Family [Member] | Purchased Impaired [Member]
Summary of aging of the loan portfolio, by class
Past Due	18,305		21,159
Current	15,340		17,093
Total loans held for investment, net	18,305		21,159		24,654
Residential 1-4 Family [Member] | Purchased Impaired [Member] | Greater Than 90 Days and still Accruing [Member]
Summary of aging of the loan portfolio, by class
Past Due	1,048		1,923
Auto [Member]
Summary of aging of the loan portfolio, by class
Nonaccrual	162		192
Current	239,877		231,264
Total loans held for investment, net	241,737		234,061		211,293
Auto [Member] | 30 to 59 Days Past Due [Member]
Summary of aging of the loan portfolio, by class
Past Due	1,519		2,312
Auto [Member] | 60 to 89 Days Past Due [Member]
Summary of aging of the loan portfolio, by class
Past Due	126		233
Auto [Member] | Greater Than 90 Days and still Accruing [Member]
Summary of aging of the loan portfolio, by class
Past Due	53		60
HELOC [Member]
Summary of aging of the loan portfolio, by class
Nonaccrual	973		1,348
Current	511,041		509,124
Total loans held for investment, net	517,122		516,726		514,750
HELOC [Member] | 30 to 59 Days Past Due [Member]
Summary of aging of the loan portfolio, by class
Past Due	1,870		2,589
HELOC [Member] | 60 to 89 Days Past Due [Member]
Summary of aging of the loan portfolio, by class
Past Due	388		1,112
HELOC [Member] | Greater Than 90 Days and still Accruing [Member]
Summary of aging of the loan portfolio, by class
Past Due	1,315		762
HELOC [Member] | Purchased Impaired [Member]
Summary of aging of the loan portfolio, by class
Past Due	1,535		1,791
Current	826		923
Total loans held for investment, net	1,535		1,791		1,889
HELOC [Member] | Purchased Impaired [Member] | Greater Than 90 Days and still Accruing [Member]
Summary of aging of the loan portfolio, by class
Past Due	546		458
Consumer and all Other [Member]
Summary of aging of the loan portfolio, by class
Nonaccrual	479		287
Current	340,573		301,339
Total loans held for investment, net	344,536		304,027		245,999
Consumer and all Other [Member] | 30 to 59 Days Past Due [Member]
Summary of aging of the loan portfolio, by class
Past Due	736		1,167
Consumer and all Other [Member] | 60 to 89 Days Past Due [Member]
Summary of aging of the loan portfolio, by class
Past Due	1,996		689
Consumer and all Other [Member] | Greater Than 90 Days and still Accruing [Member]
Summary of aging of the loan portfolio, by class
Past Due	223		19
Consumer and all Other [Member] | Purchased Impaired [Member]
Summary of aging of the loan portfolio, by class
Past Due	529		526
Current	529		526
Total loans held for investment, net	$ 529		$ 526		$ 1,350

[1] Loans, as presented, are net of deferred fees and costs totaling $3.6 million and $3.0 million as of March 31, 2016 and December 31, 2015, respectively.