FAIR VALUE - Fair Value (Detail) - USD ($) $ in Thousands	Jun. 30, 2017		Dec. 31, 2016	Jun. 30, 2016	[2]
Assets:
Investment securities available for sale	$ 1,760,045		$ 1,881,920
Held To Maturity Securities	156,049		156,190
Less: allowance for loan and lease losses	(173,485)		(205,603)
Derivatives, included in assets	398		554
Liabilities:
Other borrowings	216,187		216,187
Derivatives, included in liabilities	290		753
Fair Value Inputs Level 1 [Member]
Assets:
Loans held for investment, net of allowance	0	[1]		$ 0
Fair Value Inputs Level 2 [Member]
Assets:
Loans held for investment, net of allowance	0	[1]		0
Fair Value Inputs Level 3 [Member]
Assets:
Loans held for investment, net of allowance	359,302	[1]		$ 464,467
Carrying Reported Amount Fair Value Disclosure [Member]
Assets:
Cash and due from banks and money market investments	432,564		299,685
Investment securities available for sale	1,760,045		1,881,920
Held To Maturity Securities	156,049		156,190
Other equity securities	43,072		42,992
Loans held for sale	37,272		50,006
Loans, held for investment	8,861,176		8,886,873
Less: allowance for loan and lease losses	(173,485)		(205,603)
Loans held for investment, net of allowance	8,687,691		8,681,270
Derivatives, included in assets	398		554
Liabilities:
Deposits	8,742,893		8,831,205
Securities sold under agreements to repurchase	300,000		300,000
Advances from FHLB	675,000		670,000
Other borrowings	216,187		216,187
Derivatives, included in liabilities	290		753
Estimate Of Fair Value Fair Value Disclosure [Member]
Assets:
Cash and due from banks and money market investments	432,564		299,685
Investment securities available for sale	1,760,045		1,881,920
Held To Maturity Securities	134,944		132,759
Other equity securities	43,072		42,992
Loans held for sale	39,805		52,707
Loans held for investment, net of allowance	8,403,999		8,455,104
Derivatives, included in assets	398		554
Liabilities:
Deposits	8,750,833		8,838,606
Securities sold under agreements to repurchase	333,114		335,840
Advances from FHLB	674,573		669,687
Other borrowings	187,612		171,374
Derivatives, included in liabilities	290		753
Estimate Of Fair Value Fair Value Disclosure [Member] | Fair Value Inputs Level 1 [Member]
Assets:
Cash and due from banks and money market investments	432,564		299,685
Investment securities available for sale	7,846		7,917
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	1,732,428		1,851,089
Held To Maturity Securities	0		0
Other equity securities	43,072		42,992
Loans held for sale	30,019		42,921
Loans held for investment, net of allowance	0		0
Derivatives, included in assets	398		554
Liabilities:
Deposits	8,750,833		8,838,606
Securities sold under agreements to repurchase	333,114		335,840
Advances from FHLB	674,573		669,687
Other borrowings	0		0
Derivatives, included in liabilities	290		753
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	19,771		22,914
Held To Maturity Securities	134,944		132,759
Other equity securities	0		0
Loans held for sale	9,786		9,786
Loans held for investment, net of allowance	8,403,999		8,455,104
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	187,612		171,374
Derivatives, included in liabilities	$ 0		$ 0

[1] 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.

[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.