FAIR VALUE MEASUREMENTS - Schedule of Financial Instruments not Recorded at Fair Value (Details) - USD ($) $ in Millions		Dec. 31, 2024	Dec. 31, 2023
Financial assets:
Debt securities held to maturity	[1]	$ 8,599	$ 9,184
Debt securities held-to-maturity, fair value		7,540	8,350
Loans held for sale		33	103
Loans held for sale, fair value		33	103
Net loans and leases	[2]	137,142	143,861
Net loans and leases, fair value		136,293	140,504
Other investment securities, at cost, carrying value		710	869
Other investment securities, at cost, estimated fair value		710	869
Financial liabilities:
Deposits, carrying value		174,776	177,342
Deposits, fair value		174,651	177,096
Short-term borrowed funds		0	505
Short-term borrowed funds, fair value		0	505
Long-term borrowed funds, carrying value	[2]	12,401	13,467
Long-term borrowed funds, fair value		12,247	13,012
Level 1
Financial assets:
Debt securities held to maturity		0	0
Debt securities held-to-maturity, fair value		0	0
Loans held for sale		0	0
Loans held for sale, fair value		0	0
Net loans and leases		0	0
Net loans and leases, fair value		0	0
Other investment securities, at cost, carrying value		0	0
Other investment securities, at cost, estimated fair value		0	0
Financial liabilities:
Deposits, carrying value		0	0
Deposits, fair value		0	0
Short-term borrowed funds			0
Short-term borrowed funds, fair value		0	0
Long-term borrowed funds, carrying value		0	0
Long-term borrowed funds, fair value		0	0
Level 2
Financial assets:
Debt securities held to maturity		8,187	8,696
Debt securities held-to-maturity, fair value		7,136	7,887
Loans held for sale		0	0
Loans held for sale, fair value		0	0
Net loans and leases		979	789
Net loans and leases, fair value		979	789
Other investment securities, at cost, carrying value		689	851
Other investment securities, at cost, estimated fair value		689	851
Financial liabilities:
Deposits, carrying value		174,776	177,342
Deposits, fair value		174,651	177,096
Short-term borrowed funds			505
Short-term borrowed funds, fair value		0	505
Long-term borrowed funds, carrying value		12,401	13,467
Long-term borrowed funds, fair value		12,247	13,012
Level 3
Financial assets:
Debt securities held to maturity		412	488
Debt securities held-to-maturity, fair value		404	463
Loans held for sale		33	103
Loans held for sale, fair value		33	103
Net loans and leases		136,163	143,072
Net loans and leases, fair value		135,314	139,715
Other investment securities, at cost, carrying value		21	18
Other investment securities, at cost, estimated fair value		21	18
Financial liabilities:
Deposits, carrying value		0	0
Deposits, fair value		0	0
Short-term borrowed funds			0
Short-term borrowed funds, fair value		0	0
Long-term borrowed funds, carrying value		0	0
Long-term borrowed funds, fair value		$ 0	$ 0

[1] Includes only collateral pledged by the Company where counterparties have the right to sell or pledge the collateral.

[2] Includes amounts in consolidated VIEs. See Note 11 for additional information.