FAIR VALUE MEASUREMENTS - Schedule of Financial Instruments not Recorded at Fair Value (Details) - USD ($) $ in Millions		Dec. 31, 2022	Dec. 31, 2021
Financial assets:
Asset-backed investments included in HTM securities	[1]	$ 9,834	$ 2,242
Debt securities held-to-maturity, fair value	[1]	9,042	2,289
Other loans held for sale, carrying value		208	735
Other loans held for sale, fair value		208	735
Loans and leases		156,662	128,163
Loans and leases, fair value		151,601	128,156
Other investment securities, at cost, carrying value		1,058	624
Other investment securities, at cost, estimated fair value		1,058	624
Financial liabilities:
Deposits, carrying value		180,724	154,361
Deposits, fair value		180,566	154,366
Short-term borrowed funds		3	74
Short-term borrowed funds, fair value		3	74
Long-term borrowed funds, carrying value		15,887	6,932
Long-term borrowed funds, fair value		15,469	7,188
Level 1
Financial assets:
Asset-backed investments included in HTM securities		0	0
Debt securities held-to-maturity, fair value		0	0
Other loans held for sale, carrying value		0	0
Other loans held for sale, fair value		0	0
Loans and leases		0	0
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	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:
Asset-backed investments included in HTM securities		9,253	1,505
Debt securities held-to-maturity, fair value		8,506	1,557
Other loans held for sale, carrying value		0	0
Other loans held for sale, fair value		0	0
Loans and leases		582	645
Loans and leases, fair value		582	645
Other investment securities, at cost, carrying value		1,038	609
Other investment securities, at cost, estimated fair value		1,038	609
Financial liabilities:
Deposits, carrying value		180,724	154,361
Deposits, fair value		180,566	154,366
Short-term borrowed funds		3	74
Short-term borrowed funds, fair value		3	74
Long-term borrowed funds, carrying value		15,887	6,932
Long-term borrowed funds, fair value		15,469	7,188
Level 3
Financial assets:
Asset-backed investments included in HTM securities		581	737
Debt securities held-to-maturity, fair value		536	732
Other loans held for sale, carrying value		208	735
Other loans held for sale, fair value		208	735
Loans and leases		156,080	127,518
Loans and leases, fair value		151,019	127,511
Other investment securities, at cost, carrying value		20	15
Other investment securities, at cost, estimated fair value		20	15
Financial liabilities:
Deposits, carrying value		0	0
Deposits, fair value		0	0
Short-term borrowed funds		0	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.