INCOME TAXES - Effective Income Tax Reconciliation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Amount
U.S. Federal income tax expense	$ 489	$ 396	$ 426
State and local income taxes, net of federal income tax effect	82	46	58
Tax credits
Low income housing tax-advantaged investments	(56)	(52)	(56)
Renewable energy tax-advantaged investments	(19)	(30)	(21)
Other	(2)	(2)	(3)
Changes in valuation allowances	1	3	0
Nontaxable or nondeductible items
FDIC insurance premiums	32	34	35
Bank-owned life insurance	(24)	(22)	(20)
Other	(3)	(3)	(3)
Changes in unrecognized tax benefits	0	0	5
Other adjustments	(3)	9	1
Effective tax rate	$ 497	$ 379	$ 422
Rate
U.S. Federal income tax rate	21.00%	21.00%	21.00%
State and local income taxes, net of federal income tax effect	3.50%	2.50%	2.90%
Tax credits
Low income housing tax-advantaged investments	(2.40%)	(2.80%)	(2.80%)
Renewable energy tax-advantaged investments	(0.80%)	(1.60%)	(1.00%)
Other	(0.10%)	(0.10%)	(0.10%)
Changes in valuation allowances	0.00%	0.10%	0.00%
Nontaxable or nondeductible items
FDIC insurance premiums	1.30%	1.80%	1.70%
Bank-owned life insurance	(1.00%)	(1.20%)	(1.00%)
Other	(0.10%)	(0.10%)	(0.20%)
Changes in unrecognized tax benefits	0.00%	0.00%	0.20%
Other adjustments	(0.10%)	0.50%	0.10%
Effective tax rate	21.30%	20.10%	20.80%