DISCLOSURES ABOUT FAIR VALUE OF FINANCIAL INSTRUMENTS - Estimated Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Assets:
Cash and cash equivalents, Carrying Amount	$ 3,088,022	$ 3,846,346
Cash and cash equivalents, Estimated Fair Value	3,088,022	3,846,346
Debt securities, available for sale	2,377,733	2,376,860
Debt securities, held to maturity	1,064,437	1,103,170
Debt securities, held to maturity, fair value	1,027,514	1,046,439
Loans held for sale	275,420	340,317
Total loans and leases receivable, net of allowance for credit losses on loans and leases, Carrying Amount	13,644,538	12,726,456
Total loans and leases receivable, net of allowance for credit losses on loans and leases, Estimated Fair Value	13,511,102	12,513,386
FHLB, Federal Reserve Bank and other restricted stock, Carrying Amount	95,035	109,548
FHLB, Federal Reserve Bank and other restricted stock, Estimated Fair Value	95,035	109,548
Derivative assets	15,546	17,931
Liabilities:
Deposits, Carrying Amount	18,069,389	17,920,236
Deposits, Estimated Fair Value	18,096,656	17,922,005
FHLB advances, Carrying Amount	1,117,229	1,203,207
FHLB advances, Estimated Fair Value	1,121,074	1,188,517
Other borrowings, Carrying Amount	99,033	123,840
Other borrowings, Estimated Fair Value	78,000	103,674
Subordinated debt, Carrying Amount	182,439	182,230
Subordinated debt, Estimated Fair Value	157,542	164,233
Derivative liabilities	21,486	27,110
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash and cash equivalents, Estimated Fair Value	3,088,022	3,846,346
Debt securities, available for sale	0	0
Debt securities, held to maturity, fair value	0	0
Loans held for sale	0	0
Total loans and leases receivable, net of allowance for credit losses on loans and leases, Estimated Fair Value	0	0
FHLB, Federal Reserve Bank and other restricted stock, Estimated Fair Value	0	0
Derivative assets	0	0
Liabilities:
Deposits, Estimated Fair Value	15,638,305	14,632,357
FHLB advances, Estimated Fair Value	0	0
Other borrowings, Estimated Fair Value	0	0
Subordinated debt, Estimated Fair Value	0	0
Derivative liabilities	0	0
Significant Other Observable Inputs (Level 2)
Assets:
Cash and cash equivalents, Estimated Fair Value	0	0
Debt securities, available for sale	2,360,908	2,341,911
Debt securities, held to maturity, fair value	487,238	472,311
Loans held for sale	2,523	1,215
Total loans and leases receivable, net of allowance for credit losses on loans and leases, Estimated Fair Value	1,250,413	897,912
FHLB, Federal Reserve Bank and other restricted stock, Estimated Fair Value	95,035	109,548
Derivative assets	15,474	17,906
Liabilities:
Deposits, Estimated Fair Value	2,458,351	3,289,648
FHLB advances, Estimated Fair Value	1,121,074	1,188,517
Other borrowings, Estimated Fair Value	78,000	103,674
Subordinated debt, Estimated Fair Value	157,542	164,233
Derivative liabilities	21,486	27,110
Significant Unobservable Inputs (Level 3)
Assets:
Cash and cash equivalents, Estimated Fair Value	0	0
Debt securities, available for sale	16,825	34,949
Debt securities, held to maturity, fair value	540,276	574,128
Loans held for sale	272,897	339,102
Total loans and leases receivable, net of allowance for credit losses on loans and leases, Estimated Fair Value	12,260,689	11,615,474
FHLB, Federal Reserve Bank and other restricted stock, Estimated Fair Value	0	0
Derivative assets	72	25
Liabilities:
Deposits, Estimated Fair Value	0	0
FHLB advances, Estimated Fair Value	0	0
Other borrowings, Estimated Fair Value	0	0
Subordinated debt, Estimated Fair Value	0	0
Derivative liabilities	$ 0	$ 0