BUSINESS COMBINATIONS - Narrative (Veritex) (Details) - USD ($) $ in Millions	Oct. 20, 2025	Mar. 31, 2026	Dec. 31, 2025
Business Combination [Line Items]
Preliminary goodwill		$ 9,527	$ 5,997
Veritex Holdings, Inc.
Business Combination [Line Items]
Share issuance ratio	1.95
Consideration transferred	$ 1,684
Preliminary goodwill	$ 450
Veritex Holdings, Inc. | Veritex Shareholders Common Stock
Business Combination [Line Items]
Shares issued (in shares)	107,000,000
Veritex Holdings, Inc. | Conversion of Certain Veritex Equity Awards
Business Combination [Line Items]
Shares issued (in shares)	1,000,000