LOANS AND LEASES - Net of Unearned Income (Details) - USD ($) $ in Millions		Jun. 30, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized cost loans and leases, carrying amount	[1]	$ 31,354	$ 30,255
Total commercial loans and leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized cost loans and leases, carrying amount		19,676	19,290
Total commercial loans and leases | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized cost loans and leases, carrying amount		11,689	11,526
Total commercial loans and leases | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized cost loans and leases, carrying amount		7,248	7,131
Total commercial loans and leases | Commercial leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized cost loans and leases, carrying amount		618	519
Total commercial loans and leases | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized cost loans and leases, carrying amount		121	114
Total consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized cost loans and leases, carrying amount		11,678	10,965
Total consumer loans | Direct installment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized cost loans and leases, carrying amount		2,747	2,784
Total consumer loans | Residential mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized cost loans and leases, carrying amount		6,089	5,297
Total consumer loans | Indirect installment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized cost loans and leases, carrying amount		1,539	1,553
Total consumer loans | Consumer lines of credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized cost loans and leases, carrying amount		$ 1,303	$ 1,331

[1] Amount represents loans for which we have elected the fair value option. See Note 19.