LEASES - Schedule of Operating and Finance Lease Assets and Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024
Lease assets:
Operating lease ROU assets	$ 318	$ 316
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Other assets	Other assets
Finance leases	$ 60	$ 15
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Premises and equipment, net	Premises and equipment, net
Total lease assets	$ 378	$ 331
Lease liabilities:
Operating leases	$ 356	$ 357
Operating Lease, Liability, Statement of Financial Position [Extensible List]	Other liabilities	Other liabilities
Finance leases	$ 63	$ 15
Finance Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Other Borrowings	Other Borrowings
Total lease liabilities	$ 419	$ 372
Weighted-average remaining lease terms:
Operating leases	7 years 2 months 12 days	7 years 4 months 24 days
Finance leases	8 years	11 years 8 months 12 days
Weighted-average discount rate:
Operating leases	2.97%	2.94%
Finance leases	4.33%	3.96%