FAIR VALUE - Fair Value (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Assets:
Investment securities available for sale	$ 6,453,761	$ 4,647,019
Less: allowance for credit losses on held to maturity securities	(8,571)	(8,845)
Held To Maturity Securities Net Of Allowance For Credit Losses	169,562	180,643
Less: allowance for loan and lease losses	(269,030)	(385,887)	$ (155,139)	$ (196,362)
Loans, net of allowance for credit losses	10,791,628	11,391,402
Financial Instruments Financial Liabilities Balance Sheet Groupings [Abstract]
Other borrowings	183,762	183,762
Carrying Reported Amount Fair Value Disclosure [Member]
Assets:
Cash and due from banks and money market investments	2,543,058	1,493,833
Investment securities available for sale	6,453,761	4,647,019
Held To Maturity Securities Amortized	178,133	189,488
Less: allowance for credit losses on held to maturity securities	(8,571)	(8,845)
Held To Maturity Securities Net Of Allowance For Credit Losses	169,562	180,643
Equity Securities	32,169	37,588
Loans held for sale	35,155	50,289
Total gross loans held for investment portfolio	11,060,658	11,777,289
Less: allowance for loan and lease losses	(269,030)	(385,887)
Loans, net of allowance for credit losses	10,791,628	11,391,402
Derivative Assets	1,505	2,842
Financial Instruments Financial Liabilities Balance Sheet Groupings [Abstract]
Deposits	17,784,894	15,317,383
Securities sold under agreements to repurchase	300,000	300,000
Advances from FHLB	200,000	440,000
Other borrowings	183,762	183,762
Derivative Liabilities	1,178	1,920
Estimate Of Fair Value Fair Value Disclosure [Member]
Assets:
Cash and due from banks and money market investments	2,543,058	1,493,833
Investment securities available for sale	6,453,761	4,647,019
Held To Maturity Securities Amortized	0	0
Held To Maturity Securities Net Of Allowance For Credit Losses	167,147	173,806
Equity Securities	32,169	37,588
Loans held for sale	36,147	52,322
Loans, net of allowance for credit losses	10,900,400	11,564,635
Derivative Assets	1,505	2,842
Financial Instruments Financial Liabilities Balance Sheet Groupings [Abstract]
Deposits	17,800,706	15,363,236
Securities sold under agreements to repurchase	322,105	329,493
Advances from FHLB	202,044	446,703
Other borrowings	177,689	151,645
Derivative Liabilities	1,178	1,920
Estimate Of Fair Value Fair Value Disclosure [Member] | Fair Value Inputs Level 1 [Member]
Assets:
Cash and due from banks and money market investments	2,543,058	1,493,833
Investment securities available for sale	148,486	7,507
Held To Maturity Securities Amortized	0	0
Held To Maturity Securities Net Of Allowance For Credit Losses	0	0
Equity Securities	5,378	1,474
Loans held for sale	0	0
Loans, net of allowance for credit losses	0	0
Derivative Assets	0	0
Financial Instruments Financial Liabilities Balance Sheet Groupings [Abstract]
Deposits	0	0
Securities sold under agreements to repurchase	0	0
Advances from FHLB	0	0
Other borrowings	0	0
Derivative 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	6,294,191	4,627,535
Held To Maturity Securities Amortized	0	0
Held To Maturity Securities Net Of Allowance For Credit Losses	0	0
Equity Securities	26,791	36,114
Loans held for sale	36,147	52,322
Loans, net of allowance for credit losses	0	0
Derivative Assets	1,505	2,482
Financial Instruments Financial Liabilities Balance Sheet Groupings [Abstract]
Deposits	17,800,706	15,363,236
Securities sold under agreements to repurchase	322,105	329,493
Advances from FHLB	202,044	446,703
Other borrowings	0	0
Derivative Liabilities	1,178	1,920
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	11,084	11,977
Held To Maturity Securities Amortized	0	0
Held To Maturity Securities Net Of Allowance For Credit Losses	167,147	173,806
Equity Securities	0	0
Loans held for sale	0	0
Loans, net of allowance for credit losses	10,900,400	11,564,635
Derivative Assets	0	0
Financial Instruments Financial Liabilities Balance Sheet Groupings [Abstract]
Deposits	0	0
Securities sold under agreements to repurchase	0	0
Advances from FHLB	0	0
Other borrowings	177,689	151,645
Derivative Liabilities	$ 0	$ 0