FAIR VALUE - Fair Value (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Assets:
Investment securities available for sale	$ 1,881,920	$ 1,886,395
Less: allowance for loan and lease losses	(205,603)	(240,710)
Derivatives, included in assets	554	806
Held To Maturity Securities	156,190	161,483
Liabilities:
Other borrowings	216,187	226,492
Derivatives, included in liabilities	753	921
Carrying Reported Amount Fair Value Disclosure [Member]
Assets:
Cash and due from banks and money market investments	299,685	752,458
Investment securities available for sale	1,881,920	1,886,395
Other equity securities	42,992	32,169
Loans held for sale	50,006	35,869
Loans, held for investment	8,886,873	9,112,382
Less: allowance for loan and lease losses	(205,603)	(240,710)
Loans held for investment, net of allowance	8,681,270	8,871,672
Derivatives, included in assets	554	806
Held To Maturity Securities	156,190	161,483
Liabilities:
Deposits	8,831,205	9,338,124
Securities sold under agreements to repurchase	300,000	700,000
Advances from FHLB	670,000	455,000
Other borrowings	216,187	226,492
Derivatives, included in liabilities	753	921
Estimate Of Fair Value Fair Value Disclosure [Member]
Assets:
Cash and due from banks and money market investments	299,685	752,458
Investment securities available for sale	1,881,920	1,886,395
Other equity securities	42,992	32,169
Loans held for sale	52,707	36,844
Loans held for investment, net of allowance	8,455,104	8,768,152
Derivatives, included in assets	554	806
Held To Maturity Securities	132,759	131,544
Liabilities:
Deposits	8,838,606	9,334,073
Securities sold under agreements to repurchase	335,840	752,048
Advances from FHLB	669,687	453,182
Other borrowings	171,374	142,846
Derivatives, included in liabilities	753	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	299,685	752,458
Investment securities available for sale	7,917	7,497
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
Held To Maturity Securities	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	1,851,089	1,851,601
Other equity securities	42,992	32,169
Loans held for sale	42,921	28,709
Loans held for investment, net of allowance	0	0
Derivatives, included in assets	554	806
Held To Maturity Securities	0	0
Liabilities:
Deposits	8,838,606	9,334,073
Securities sold under agreements to repurchase	335,840	752,048
Advances from FHLB	669,687	453,182
Other borrowings	0	0
Derivatives, included in liabilities	753	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	22,914	27,297
Other equity securities	0	0
Loans held for sale	9,786	8,135
Loans held for investment, net of allowance	8,455,104	8,768,152
Derivatives, included in assets	0	0
Held To Maturity Securities	132,759	131,544
Liabilities:
Deposits	0	0
Securities sold under agreements to repurchase	0	0
Advances from FHLB	0	0
Other borrowings	171,374	142,846
Derivatives, included in liabilities	$ 0	$ 0