FAIR VALUE - Fair Value (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Assets:
Investment securities available for sale	$ 5,229,984	$ 5,599,520
Held To Maturity Securities Amortized	354,178	437,537
Less: allowance for credit losses on held to maturity securities	(2,197)	(8,286)
Loans held for investment	12,185,483	11,552,825
ACL for loans and finance leases	(261,843)	(260,464)	$ (269,030)	$ (385,887)
Loans held for investment, net of ACL	11,923,640	11,292,361
Mortgage servicing rights	26,941	29,037	$ 30,986	$ 33,071
Advances from the Federal Home Loan Bank ("FHLB"):
Other long-term borrowings	161,700	183,762
Carrying Reported Amount Fair Value Disclosure [Member]
Assets:
Cash and due from banks and money market investments	663,164	480,505
Investment securities available for sale	5,229,984	5,599,520
Held To Maturity Securities Amortized	354,178	437,537
Less: allowance for credit losses on held to maturity securities	(2,197)	(8,286)
Investment securities held to maturity, net of ACL	351,981	429,251
Equity securities	44,782	50,428
Other investment securities	4,893	4,861
Loans held for sale	7,368	12,306
Loans held for investment	12,185,483	11,552,825
ACL for loans and finance leases	(261,843)	(260,464)
Loans held for investment, net of ACL	11,923,640	11,292,361
Mortgage servicing rights	26,941	29,037
Derivative Assets	341	633
Financial Instruments Financial Liabilities Balance Sheet Groupings [Abstract]
Deposits	16,555,985	16,143,467
Short-term securities sold under agreements to repurchase (amortized cost)		75,133
Advances from the Federal Home Loan Bank ("FHLB"):
Short-term		475,000
Long-term	500,000	200,000
Other long-term borrowings	161,700	183,762
Derivative Liabilities	317	476
Federal Home Loan Bank Stock	34,600	42,900
Estimate Of Fair Value Fair Value Disclosure [Member]
Assets:
Cash and due from banks and money market investments	663,164	480,505
Investment securities available for sale	5,229,984	5,599,520
Investment securities held to maturity, net of ACL	346,132	427,115
Equity securities	44,782	50,428
Other investment securities	4,893	4,861
Loans held for sale	7,476	12,306
Loans held for investment, net of ACL	11,762,855	11,106,809
Mortgage servicing rights	45,244	44,710
Derivative Assets	341	633
Financial Instruments Financial Liabilities Balance Sheet Groupings [Abstract]
Deposits	16,565,435	16,139,937
Short-term securities sold under agreements to repurchase (amortized cost)		75,230
Advances from the Federal Home Loan Bank ("FHLB"):
Short-term		474,731
Long-term	500,522	199,865
Other long-term borrowings	159,999	187,246
Derivative Liabilities	317	476
Estimate Of Fair Value Fair Value Disclosure [Member] | Fair Value Inputs Level 1 [Member]
Assets:
Cash and due from banks and money market investments	663,164	480,505
Investment securities available for sale	135,393	138,875
Investment securities held to maturity, net of ACL	0	0
Equity securities	0	0
Other investment securities	4,893	4,861
Loans held for sale	0	0
Loans held for investment, net of ACL	0	0
Mortgage servicing rights	0	0
Derivative Assets	0	0
Financial Instruments Financial Liabilities Balance Sheet Groupings [Abstract]
Deposits	0	0
Short-term securities sold under agreements to repurchase (amortized cost)		0
Advances from the Federal Home Loan Bank ("FHLB"):
Short-term		0
Long-term	0	0
Other long-term 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	5,088,391	5,452,150
Investment securities held to maturity, net of ACL	235,239	260,106
Equity securities	44,782	50,428
Other investment securities	0	0
Loans held for sale	7,476	12,306
Loans held for investment, net of ACL	0	0
Mortgage servicing rights	0	0
Derivative Assets	341	633
Financial Instruments Financial Liabilities Balance Sheet Groupings [Abstract]
Deposits	16,565,435	16,139,937
Short-term securities sold under agreements to repurchase (amortized cost)		75,230
Advances from the Federal Home Loan Bank ("FHLB"):
Short-term		474,731
Long-term	500,522	199,865
Other long-term borrowings	0	0
Derivative Liabilities	317	476
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	6,200	8,495
Investment securities held to maturity, net of ACL	110,893	167,009
Equity securities	0	0
Other investment securities	0	0
Loans held for sale	0	0
Loans held for investment, net of ACL	11,762,855	11,106,809
Mortgage servicing rights	45,244	44,710
Derivative Assets	0	0
Financial Instruments Financial Liabilities Balance Sheet Groupings [Abstract]
Deposits	0	0
Short-term securities sold under agreements to repurchase (amortized cost)		0
Advances from the Federal Home Loan Bank ("FHLB"):
Short-term		0
Long-term	0	0
Other long-term borrowings	159,999	187,246
Derivative Liabilities	$ 0	$ 0