OTHER BORROWINGS AND SUBORDINATED NOTES AND DEBENTURES - Narrative (Details) - USD ($)	1 Months Ended		3 Months Ended	12 Months Ended	33 Months Ended
	Sep. 30, 2025	Mar. 31, 2018	Sep. 30, 2025	Dec. 31, 2025	Dec. 31, 2025	Dec. 31, 2024	Apr. 30, 2022
Debt Instrument [Line Items]
Advances from FHLB				$ 286,600,000	$ 286,600,000	$ 727,900,000
Mortgage loans and investment securities securing FHLB advances				7,080,000,000.00	7,080,000,000.00
Additional advances from FHLB				6,000,000,000.00	6,000,000,000.00
Subordinated Debt
Debt Instrument [Line Items]
Face amount of debt	$ 325,000,000.0	$ 330,000,000.0	$ 325,000,000.0	$ 325,000,000.0	$ 325,000,000.0
Debt instrument, interest rate		5.00%
Offering price, percent	100.00%	100.00%	100.00%
Debt issuance costs incurred	$ 3,900,000	$ 3,600,000
Deferred debt issuance cost, writeoff			$ 565,000
Subordinated Debt | LIBOR
Debt Instrument [Line Items]
Floating rate (as percent)					2.15%
Subordinated Debt | SOFR
Debt Instrument [Line Items]
Floating rate (as percent)	3.02%				0.26161%
Subordinated Debt | Subordinated Notes Payable Due
Debt Instrument [Line Items]
Debt instrument, interest rate				6.00%	6.00%
Long-term debt, gross				$ 0	$ 0	$ 37,057,000
Subordinated Debt | Subordinated Notes Payable Due | Spirit of Texas Bancshares, Inc.
Debt Instrument [Line Items]
Debt instrument, interest rate							6.00%
Long-term debt, gross							$ 37,400,000
Subordinated Debt | Subordinated Notes Payable Due | SOFR
Debt Instrument [Line Items]
Floating rate (as percent)				5.92%