LOANS, LEASES, AND ALLOWANCE FOR CREDIT LOSSES (Summary of Major Portfolio Segment and Specific Loan Class) (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans held for sale	$ 97	$ 53
Total loans and leases	58,884	57,779
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	30,785	30,588
Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	16,757	16,684
Commercial | Leasing
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	377	383
Commercial | Owner-occupied
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	9,381	9,219
Commercial | Municipal
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	4,270	4,302
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	13,483	13,371
Commercial real estate | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	2,833	2,669
Commercial real estate | Term
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	10,650	10,702
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	14,616	13,820
Consumer | Home equity credit line
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	3,543	3,356
Consumer | 1-4 family residential
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	9,489	8,415
Consumer | Construction and other consumer real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	997	1,442
Consumer | Bankcard and other revolving plans
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	461	474
Consumer | Other
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	$ 126	$ 133