LEASES - Schedule of Operating and Finance Lease Assets and Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Lease assets:
Operating lease ROU assets	$ 305	$ 316
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Other assets	Other assets
Finance leases	$ 67	$ 15
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Premises and equipment, net	Premises and equipment, net
Total lease assets	$ 372	$ 331
Lease liabilities:
Operating leases	$ 342	$ 357
Operating Lease, Liability, Statement of Financial Position [Extensible List]	Other liabilities	Other liabilities
Finance leases	$ 67	$ 15
Finance Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Other Borrowings	Other Borrowings
Total lease liabilities	$ 409	$ 372
Weighted-average remaining lease terms:
Operating leases	7 years 3 months 18 days	7 years 4 months 24 days
Finance leases	8 years 1 month 6 days	11 years 8 months 12 days
Weighted-average discount rate:
Operating leases	3.10%	2.94%
Finance leases	4.20%	3.96%