NONINTEREST INCOME - Components of Revenue from Contracts with Customers (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 1,635	$ 1,533	$ 1,266
Total noninterest income	2,394	2,176	1,983
Bank-owned life insurance	115	108	93
Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from other sources	759	643	717
Total noninterest income	2,394	2,176	1,983
Consumer Banking | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	955	869	783
Total revenue from other sources	297	262	284
Total noninterest income	1,252	1,131	1,067
Commercial Banking | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	680	639	483
Total revenue from other sources	315	269	301
Total noninterest income	995	908	784
Other | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	25	0
Total revenue from other sources	147	112	132
Total noninterest income	147	137	132
Service charges and fees
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	442	417	409
Service charges and fees | Consumer Banking | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	308	288	277
Service charges and fees | Commercial Banking | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	134	128	132
Service charges and fees | Other | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	1	0
Capital markets fees
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	485	445	293
Capital markets fees | Consumer Banking | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0
Capital markets fees | Commercial Banking | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	485	445	293
Capital markets fees | Other | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0
Wealth fees
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	360	294	259
Wealth fees | Consumer Banking | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	360	294	259
Wealth fees | Commercial Banking | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0
Wealth fees | Other | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0
Card fees
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	335	362	291
Card fees | Consumer Banking | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	284	284	244
Card fees | Commercial Banking | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	51	54	47
Card fees | Other | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	24	0
Other banking fees
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	13	15	14
Other banking fees | Consumer Banking | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3	3	3
Other banking fees | Commercial Banking | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	10	12	11
Other banking fees | Other | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 0	$ 0	$ 0