LEASES - Schedule of Operating and Finance Lease Assets and Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Lease assets:
Operating lease ROU assets	$ 344	$ 354
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Other assets	Other assets
Finance leases	$ 8	$ 9
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Premises and equipment, net	Premises and equipment, net
Total lease assets	$ 352	$ 363
Lease liabilities:
Operating leases	$ 385	$ 396
Operating Lease, Liability, Statement of Financial Position [Extensible List]	Other liabilities	Other liabilities
Finance leases	$ 8	$ 9
Finance Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Other Borrowings	Other Borrowings
Total lease liabilities	$ 393	$ 405
Weighted-average remaining lease terms:
Operating leases	7 years 8 months 12 days	8 years 1 month 6 days
Finance leases	16 years 1 month 6 days	15 years 4 months 24 days
Weighted-average discount rate:
Operating leases	2.79%	2.70%
Finance leases	3.59%	3.52%