FAIR VALUE - Fair Value (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014 Fair Value Inputs Level 1 [Member]		Sep. 30, 2013 Fair Value Inputs Level 1 [Member]		Sep. 30, 2014 Fair Value Inputs Level 2 [Member]		Sep. 30, 2013 Fair Value Inputs Level 2 [Member]		Sep. 30, 2014 Fair Value Inputs Level 3 [Member]		Sep. 30, 2013 Fair Value Inputs Level 3 [Member]		Sep. 30, 2014 Carrying Reported Amount Fair Value Disclosure [Member]	Dec. 31, 2013 Carrying Reported Amount Fair Value Disclosure [Member]	Sep. 30, 2014 Estimate Of Fair Value Fair Value Disclosure [Member]	Dec. 31, 2013 Estimate Of Fair Value Fair Value Disclosure [Member]	Sep. 30, 2014 Estimate Of Fair Value Fair Value Disclosure [Member] Fair Value Inputs Level 1 [Member]	Dec. 31, 2013 Estimate Of Fair Value Fair Value Disclosure [Member] Fair Value Inputs Level 1 [Member]	Sep. 30, 2014 Estimate Of Fair Value Fair Value Disclosure [Member] Fair Value Inputs Level 2 [Member]	Dec. 31, 2013 Estimate Of Fair Value Fair Value Disclosure [Member] Fair Value Inputs Level 2 [Member]	Sep. 30, 2014 Estimate Of Fair Value Fair Value Disclosure [Member] Fair Value Inputs Level 3 [Member]	Dec. 31, 2013 Estimate Of Fair Value Fair Value Disclosure [Member] Fair Value Inputs Level 3 [Member]
Assets:
Cash and due from banks and money market investments															$ 969,995	$ 655,671	$ 969,995	$ 655,671	$ 969,995	$ 655,671	$ 0	$ 0	$ 0	$ 0
Investment securities available for sale	1,977,137	1,978,282													1,977,137	1,978,282	1,977,137	1,978,282	7,512	7,532	1,930,743	1,927,458	38,882	43,292
Other equity securities															25,752	28,691	25,752	28,691	0	0	25,752	28,691	0	0
Loans held for sale			0	[1]	0	[2]	0	[1]	0	[2]	54,641	[1]	80,234	[2]	80,014	75,969	80,937	76,684	0	0	26,296	21,883	54,641	54,801
Loans, held for investment															9,315,402	9,636,170
Less: allowance for loan and lease losses	(225,434)	(285,858)													(225,434)	(285,858)
Loans held for investment, net of allowance			0	[3]	0	[4]	0	[3]	0	[4]	461,882	[3]	450,267	[4]	9,089,968	9,350,312	8,853,184	9,127,234	0	0	0	0	8,853,184	9,127,234
Derivatives, included in assets	102	394													102	394	102	394	0	0	102	394	0	0
Liabilities:
Deposits															9,703,174	9,879,924	9,702,567	9,898,615	0	0	9,702,567	9,898,615	0	0
Securities sold under agreements to repurchase															900,000	900,000	964,946	976,151	0	0	964,946	976,151	0	0
Advances from FHLB															325,000	300,000	323,656	297,523	0	0	323,656	297,523	0	0
Other borrowings	231,959	231,959													231,959	231,959	137,127	106,772	0	0	0	0	137,127	106,772
Derivatives, included in liabilities	$ 2,911	$ 4,023													$ 2,911	$ 4,023	$ 2,911	$ 4,023	$ 0	$ 0	$ 2,911	$ 4,023	$ 0	$ 0

[1] The value of these loans was derived from external appraisals, adjusted for specific characteristics of the loans, and for loans with signed sale agreements, the value was determined based on the sales price on such agreements.

[2] The value of these loans was derived from external appraisals, adjusted for specific characteristics of the loans, and, for loans with signed sale agreements, the value was determined based on the sales price on such agreements.

[3] Mainly 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.

[4]  Mainly 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.