FAIR VALUE - Fair Value (Detail) - USD ($) $ in Thousands	Sep. 30, 2016		Dec. 31, 2015	Sep. 30, 2015
Assets:
Investment securities available for sale	$ 1,843,853		$ 1,886,395
Held To Maturity Securities	156,190		161,483
Less: allowance for loan and lease losses	(214,070)		(240,710)
Derivatives, included in assets	195		806
Liabilities:
Other borrowings	216,187		226,492
Derivatives, included in liabilities	335		921
Fair Value Inputs Level 1 [Member]
Assets:
Loans held for sale	0			$ 0	[1]
Loans held for investment, net of allowance	0	[2]		0	[3]
Fair Value Inputs Level 2 [Member]
Assets:
Loans held for sale	0			0	[1]
Loans held for investment, net of allowance	0	[2]		0	[3]
Fair Value Inputs Level 3 [Member]
Assets:
Loans held for sale	0			8,027	[1]
Loans held for investment, net of allowance	426,444	[2]		$ 332,688	[3]
Carrying Reported Amount Fair Value Disclosure [Member]
Assets:
Cash and due from banks and money market investments	528,943		752,458
Investment securities available for sale	1,843,853		1,886,395
Held To Maturity Securities	156,190		161,483
Other equity securities	28,717		32,169
Loans held for sale	56,779		35,869
Loans, held for investment	8,863,654		9,112,382
Less: allowance for loan and lease losses	(214,070)		(240,710)
Loans held for investment, net of allowance	8,649,584		8,871,672
Derivatives, included in assets	195		806
Liabilities:
Deposits	8,981,313		9,338,124
Securities sold under agreements to repurchase	600,000		700,000
Advances from FHLB	355,000		455,000
Other borrowings	216,187		226,492
Derivatives, included in liabilities	335		921
Estimate Of Fair Value Fair Value Disclosure [Member]
Assets:
Cash and due from banks and money market investments	528,943		752,458
Investment securities available for sale	1,843,853		1,886,395
Held To Maturity Securities	132,241		131,544
Other equity securities	28,717		32,169
Loans held for sale	60,283		36,844
Loans held for investment, net of allowance	8,462,434		8,768,152
Derivatives, included in assets	195		806
Liabilities:
Deposits	9,003,706		9,334,073
Securities sold under agreements to repurchase	646,505		752,048
Advances from FHLB	356,925		453,182
Other borrowings	174,997		142,846
Derivatives, included in liabilities	335		921
Estimate Of Fair Value Fair Value Disclosure [Member] | Fair Value Inputs Level 1 [Member]
Assets:
Cash and due from banks and money market investments	528,943		752,458
Investment securities available for sale	7,933		7,497
Held To Maturity Securities	0		0
Other equity securities	0		0
Loans held for sale	0		0
Loans held for investment, net of allowance	0		0
Derivatives, included in assets	0		0
Liabilities:
Deposits	0		0
Securities sold under agreements to repurchase	0		0
Advances from FHLB	0		0
Other borrowings	0		0
Derivatives, included in liabilities	0		0
Estimate Of Fair Value Fair Value Disclosure [Member] | Fair Value Inputs Level 2 [Member]
Assets:
Cash and due from banks and money market investments	0		0
Investment securities available for sale	1,811,442		1,851,601
Held To Maturity Securities	0		0
Other equity securities	28,717		32,169
Loans held for sale	50,497		28,709
Loans held for investment, net of allowance	0		0
Derivatives, included in assets	195		806
Liabilities:
Deposits	9,003,706		9,334,073
Securities sold under agreements to repurchase	646,505		752,048
Advances from FHLB	356,925		453,182
Other borrowings	0		0
Derivatives, included in liabilities	335		921
Estimate Of Fair Value Fair Value Disclosure [Member] | Fair Value Inputs Level 3 [Member]
Assets:
Cash and due from banks and money market investments	0		0
Investment securities available for sale	24,478		27,297
Held To Maturity Securities	132,241		131,544
Other equity securities	0		0
Loans held for sale	9,786		8,135
Loans held for investment, net of allowance	8,462,434		8,768,152
Derivatives, included in assets	0		0
Liabilities:
Deposits	0		0
Securities sold under agreements to repurchase	0		0
Advances from FHLB	0		0
Other borrowings	174,997		142,846
Derivatives, included in liabilities	$ 0		$ 0

[1] The value of these loans was derived from external appraisals, adjusted for specific characteristics of the loans.

[2] Consist mainly of impaired commercial and construction loans. The impairment was generally measured based on the fair value of the collateral. The fair value was derived from external appraisals that take into consideration prices in observed transactions involving similar assets in similar locations but adjusted for specific characteristics and assumptions of the collateral (e.g. absorption rates), which are not market observable.

[3] Consist mainly of impaired commercial and construction loans. The impairment was generally measured based on the fair value of the collateral. The fair value was derived from external appraisals that take into consideration prices in observed transactions involving similar assets in similar locations but adjusted for specific characteristics and assumptions of the collateral (e.g. absorption rates), which are not market observable.