GOODWILL AND CORE DEPOSIT INTANGIBLES - Schedule of Gross Carrying Amount and Accumulated Amortization of Core Deposit Intangibles (Details) - Core deposit intangible - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Acquired Finite-Lived Intangible Assets [Line Items]
Gross balance	$ 501	$ 501
Less: accumulated amortization	221	189
Balance, net of accumulated amortization	$ 280	$ 312