BUSINESS COMBINATIONS - Assets Acquired and Liabilities Assumed (Veritex) (Details) - USD ($) $ in Millions	Oct. 20, 2025	Mar. 31, 2026	Dec. 31, 2025
Liabilities assumed
Preliminary goodwill		$ 9,527	$ 5,997
Veritex Holdings, Inc.
Business Combination [Line Items]
Cash	$ 2
Total consideration	1,684
Assets acquired
Cash and due from banks	19
Interest-earning deposits with banks	943
Available-for-sale securities	1,274
Other securities	76
Loans held for sale	83
Loans and leases	9,300
Allowance for loan and lease losses	(143)
Net loans and leases	9,157
Bank-owned life insurance	87
Premises and equipment	135
Servicing rights and other intangible assets	105
Other assets	147
Total assets acquired	12,026
Liabilities assumed
Deposits	10,516
Long-term debt	159
Other liabilities	117
Total liabilities assumed	10,792
Preliminary fair value of net assets acquired	1,234
Preliminary goodwill	450
Veritex Holdings, Inc. | Common Stock
Business Combination [Line Items]
Fair value of equity interests	1,659
Veritex Holdings, Inc. | Equity-based Awards
Business Combination [Line Items]
Fair value of equity interests	$ 23