NONINTEREST INCOME - Components of Revenue from Contracts with Customers (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 367	$ 310	$ 1,136	$ 942
Total revenue from other sources	165	182	466	541
Total noninterest income	532	492	1,602	1,483
Bank-owned life insurance income	26	24	80	70
Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	6	1	14	1
Total revenue from other sources	34	33	92	92
Total noninterest income	40	34	106	93
Consumer Banking \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	225	198	647	586
Total revenue from other sources	60	80	173	216
Total noninterest income	285	278	820	802
Commercial Banking \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	136	111	475	355
Total revenue from other sources	71	69	201	233
Total noninterest income	207	180	676	588
Non-Core \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Total revenue from other sources	0	0	0	0
Total noninterest income	0	0	0	0
Service charges and fees
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	109	105	310	305
Service charges and fees \| Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	1	0	1
Service charges and fees \| Consumer Banking \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	75	73	213	206
Service charges and fees \| Commercial Banking \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	34	31	97	98
Service charges and fees \| Non-Core \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Card fees
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	91	74	266	223
Card fees \| Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	6	0	13	0
Card fees \| Consumer Banking \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	73	62	213	188
Card fees \| Commercial Banking \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	12	12	40	35
Card fees \| Non-Core \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Capital markets fees
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	88	64	330	211
Capital markets fees \| Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Capital markets fees \| Consumer Banking \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Capital markets fees \| Commercial Banking \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	88	64	330	211
Capital markets fees \| Non-Core \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Wealth fees
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	76	63	219	191
Wealth fees \| Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Wealth fees \| Consumer Banking \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	76	62	219	190
Wealth fees \| Commercial Banking \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	1	0	1
Wealth fees \| Non-Core \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Other banking fees
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3	4	11	12
Other banking fees \| Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	1	0
Other banking fees \| Consumer Banking \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1	1	2	2
Other banking fees \| Commercial Banking \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2	3	8	10
Other banking fees \| Non-Core \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 0	$ 0	$ 0	$ 0

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The total amount of noninterest income which may be derived from: (1) fees and commissions; (2) premiums earned; (3) insurance policy charges; (4) the sale or disposal of assets; and (5) other sources not otherwise specified.

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