FAIR VALUES OF ASSETS AND LIABILITIES - Balance Sheet Location (Details) - USD ($) $ in Millions		Sep. 30, 2025	Dec. 31, 2024
Reported Value Measurement
Financial Assets
Cash and short-term assets		$ 13,232	$ 13,332
Trading account securities		81	53
Available-for-sale securities		26,085	27,273
Held-to-maturity securities		15,597	16,368
Other securities		870	823
Loans held for sale		823	654
Net loans and leases		135,582	127,798
Derivative assets, net		211	266
Assets held in trust for deferred compensation plans		211	191
Financial Liabilities
Total deposits		165,212	162,448
Short-term borrowings		252	199
Long-term borrowings		17,315	16,374
Derivative liabilities, net		345	578
Estimate of Fair Value Measurement
Financial Assets
Cash and short-term assets		13,232	13,332
Trading account securities		81	53
Available-for-sale securities		26,085	27,273
Held-to-maturity securities		13,869	14,086
Other securities		870	823
Loans held for sale		823	654
Net loans and leases		134,953	125,557
Derivative assets, net		211	266
Assets held in trust for deferred compensation plans		211	191
Other securities		32	31
Financial Liabilities
Total deposits		165,212	162,455
Short-term borrowings		252	199
Long-term borrowings		17,571	16,573
Derivative liabilities, net		345	578
Estimate of Fair Value Measurement | Level 1
Financial Assets
Trading account securities		2	1
Available-for-sale securities		5,410	6,556
Held-to-maturity securities		2,354	2,023
Loans held for sale		0	0
Net loans and leases		0	0
Other securities		30	29
Financial Liabilities
Total deposits		0	0
Short-term borrowings		57	0
Long-term borrowings		0	0
Estimate of Fair Value Measurement | Level 2
Financial Assets
Trading account securities		79	52
Available-for-sale securities		16,524	16,693
Held-to-maturity securities		11,515	12,063
Loans held for sale		817	652
Net loans and leases		108	113
Other securities		2	2
Financial Liabilities
Total deposits		151,413	147,045
Short-term borrowings		195	199
Long-term borrowings		12,415	11,242
Estimate of Fair Value Measurement | Level 3
Financial Assets
Trading account securities		0	0
Available-for-sale securities		4,151	4,024
Held-to-maturity securities		0	0
Loans held for sale		6	2
Net loans and leases		134,845	125,444
Other securities		0	0
Financial Liabilities
Total deposits		13,799	15,410
Short-term borrowings		0	0
Long-term borrowings		5,156	5,331
Available-for-sale securities		26,085	27,273
Held-to-maturity securities		15,597	16,368
Loans held for sale		823	654
Net loans and leases	[1]	135,582	127,798
Derivative assets, gross		502	610
Derivative assets, netting adjustments		(291)	(344)
Derivative assets, net		211	266
Total deposits		165,212	162,448
Short-term borrowings		252	199
Long-term borrowings	[1]	17,315	16,374
Derivative liabilities, gross		508	668
Derivative liabilities, netting adjustments		(163)	(90)
Derivative liabilities, net		345	578
Time deposits in excess of the FDIC insurance coverage limit		1,300	1,500
Fair Value, Recurring | Estimate of Fair Value Measurement
Financial Assets
Derivative assets, netting adjustments		(291)	(344)
Derivative assets, net		211	266
Financial Liabilities
Derivative liabilities, netting adjustments		(163)	(90)
Derivative liabilities, net		345	578
Fair Value, Recurring | Estimate of Fair Value Measurement | Level 2
Financial Assets
Derivative assets, gross		493	606
Financial Liabilities
Derivative liabilities, gross		502	666
Fair Value, Recurring | Estimate of Fair Value Measurement | Level 3
Financial Assets
Derivative assets, gross		9	4
Financial Liabilities
Derivative liabilities, gross		6	2
Fair Value, Recurring
Financial Assets
Available-for-sale securities		26,085	27,273
Derivative assets, gross			266
Derivative assets, netting adjustments		(291)	(344)
Derivative assets, net		211
Financial Liabilities
Short-term borrowings		69
Long-term borrowings		1,299	821
Derivative liabilities, gross			578
Derivative liabilities, netting adjustments		(163)	(90)
Derivative liabilities, net		345
Fair Value, Recurring | Level 1
Financial Assets
Available-for-sale securities		5,410	6,556
Derivative assets, gross		0	0
Financial Liabilities
Short-term borrowings		57
Long-term borrowings		0	0
Derivative liabilities, gross		0	0
Fair Value, Recurring | Level 2
Financial Assets
Available-for-sale securities		16,524	16,693
Derivative assets, gross		493	606
Financial Liabilities
Short-term borrowings		12
Long-term borrowings		1,299	821
Derivative liabilities, gross		502	666
Fair Value, Recurring | Level 3
Financial Assets
Available-for-sale securities		4,151	4,024
Derivative assets, gross		9	4
Financial Liabilities
Short-term borrowings		0
Long-term borrowings		0	0
Derivative liabilities, gross		6	2
Amortized Cost | Reported Value Measurement
Financial Assets
Cash and short-term assets		13,232	13,332
Held-to-maturity securities		15,597	16,368
Other securities		838	792
Net loans and leases		135,411	127,625
Financial Liabilities
Total deposits		165,212	162,448
Short-term borrowings		183	199
Long-term borrowings		16,016	15,553
Lower of Cost or Market | Reported Value Measurement
Financial Assets
Loans held for sale		6	2
Fair Value or Fair Value Option | Reported Value Measurement
Financial Assets
Trading account securities		81	53
Available-for-sale securities		26,085	27,273
Other securities		32	31
Loans held for sale		817	652
Net loans and leases		171	173
Derivative assets, net		211	266
Assets held in trust for deferred compensation plans		211	191
Financial Liabilities
Short-term borrowings		69
Long-term borrowings		1,299	821
Derivative liabilities, net		$ 345	$ 578

[1] Includes VIE balances in net loans and leases, other assets, long-term debt, and other liabilities of $769 million, $334 million, $694 million, and $123 million, respectively, at September 30, 2025, and $1.1 billion, $264 million, $1.0 billion, and $109 million, respectively, at December 31, 2024. See Note 15 - “Variable Interest Entities” for additional information.