FAIR VALUE - Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2024	Dec. 31, 2025
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	$ 33,750	$ 31,790
Marketable equity securities	101	127
Total derivative assets	660	534
Total derivative liabilities	$ 625	494
Derivative Liability Statement Of Financial Position Extensible Enumeration Not Disclosed Flag [Extensible Enumeration]	Total derivative liabilities
U.S. Treasury
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	$ 13,903	10,673
Residential mortgage-backed securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	15,620	17,623
Commercial mortgage-backed securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	3,666	3,299
Municipal bonds
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	17	12
Fair Value, Recurring
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	33,750	31,790
Marketable equity securities	101	127
Loans held for sale	55	87
Loans		22
Total derivative assets	660	534
Total derivative liabilities	625	494
Fair Value, Recurring \| Non-qualifying Hedges
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total derivative assets	659	534
Total derivative liabilities	625	494
Fair Value, Recurring \| Interest rate contracts \| Qualifying Hedges
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total derivative assets	1	0
Total derivative liabilities	0	0
Fair Value, Recurring \| Interest rate contracts \| Non-qualifying Hedges
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total derivative assets	491	385
Total derivative liabilities	516	381
Fair Value, Recurring \| Foreign exchange contract \| Non-qualifying Hedges
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total derivative assets	152	122
Total derivative liabilities	108	113
Fair Value, Recurring \| Other derivative \| Non-qualifying Hedges
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total derivative assets	16	27
Total derivative liabilities	1	0
Fair Value, Recurring \| Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	0	0
Marketable equity securities	48	50
Loans held for sale	0	0
Loans		0
Total derivative assets	0	0
Total derivative liabilities	0	0
Fair Value, Recurring \| Level 1 \| Non-qualifying Hedges
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total derivative assets	0	0
Total derivative liabilities	0	0
Fair Value, Recurring \| Level 1 \| Interest rate contracts \| Qualifying Hedges
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total derivative assets	0	0
Total derivative liabilities	0	0
Fair Value, Recurring \| Level 1 \| Interest rate contracts \| Non-qualifying Hedges
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total derivative assets	0	0
Total derivative liabilities	0	0
Fair Value, Recurring \| Level 1 \| Foreign exchange contract \| Non-qualifying Hedges
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total derivative assets	0	0
Total derivative liabilities	0	0
Fair Value, Recurring \| Level 1 \| Other derivative \| Non-qualifying Hedges
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total derivative assets	0	0
Total derivative liabilities	0	0
Fair Value, Recurring \| Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	33,582	31,767
Marketable equity securities	53	77
Loans held for sale	55	87
Loans		22
Total derivative assets	643	505
Total derivative liabilities	624	494
Fair Value, Recurring \| Level 2 \| Non-qualifying Hedges
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total derivative assets	642	505
Total derivative liabilities	624	494
Fair Value, Recurring \| Level 2 \| Interest rate contracts \| Qualifying Hedges
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total derivative assets	1	0
Total derivative liabilities	0	0
Fair Value, Recurring \| Level 2 \| Interest rate contracts \| Non-qualifying Hedges
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total derivative assets	490	383
Total derivative liabilities	516	381
Fair Value, Recurring \| Level 2 \| Foreign exchange contract \| Non-qualifying Hedges
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total derivative assets	152	122
Total derivative liabilities	108	113
Fair Value, Recurring \| Level 2 \| Other derivative \| Non-qualifying Hedges
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total derivative assets	0	0
Total derivative liabilities	0	0
Fair Value, Recurring \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	168	23
Marketable equity securities	0	0
Loans held for sale	0	0
Loans		0
Total derivative assets	17	29
Total derivative liabilities	1	0
Fair Value, Recurring \| Level 3 \| Non-qualifying Hedges
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total derivative assets	17	29
Total derivative liabilities	1	0
Fair Value, Recurring \| Level 3 \| Interest rate contracts \| Qualifying Hedges
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total derivative assets	0	0
Total derivative liabilities	0	0
Fair Value, Recurring \| Level 3 \| Interest rate contracts \| Non-qualifying Hedges
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total derivative assets	1	2
Total derivative liabilities	0	0
Fair Value, Recurring \| Level 3 \| Foreign exchange contract \| Non-qualifying Hedges
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total derivative assets	0	0
Total derivative liabilities	0	0
Fair Value, Recurring \| Level 3 \| Other derivative \| Non-qualifying Hedges
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total derivative assets	16	27
Total derivative liabilities	1	0
Fair Value, Recurring \| U.S. Treasury
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	13,903	10,673
Fair Value, Recurring \| U.S. Treasury \| Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	0	0
Fair Value, Recurring \| U.S. Treasury \| Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	13,903	10,673
Fair Value, Recurring \| U.S. Treasury \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	0	0
Fair Value, Recurring \| Government agency
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	77	43
Fair Value, Recurring \| Government agency \| Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	0	0
Fair Value, Recurring \| Government agency \| Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	77	43
Fair Value, Recurring \| Government agency \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	0	0
Fair Value, Recurring \| Residential mortgage-backed securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	15,620	17,623
Fair Value, Recurring \| Residential mortgage-backed securities \| Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	0	0
Fair Value, Recurring \| Residential mortgage-backed securities \| Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	15,620	17,623
Fair Value, Recurring \| Residential mortgage-backed securities \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	0	0
Fair Value, Recurring \| Commercial mortgage-backed securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	3,666	3,299
Fair Value, Recurring \| Commercial mortgage-backed securities \| Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	0	0
Fair Value, Recurring \| Commercial mortgage-backed securities \| Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	3,666	3,299
Fair Value, Recurring \| Commercial mortgage-backed securities \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	0	0
Fair Value, Recurring \| Corporate bonds
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	467	140
Fair Value, Recurring \| Corporate bonds \| Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	0	0
Fair Value, Recurring \| Corporate bonds \| Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	299	117
Fair Value, Recurring \| Corporate bonds \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	168	23
Fair Value, Recurring \| Municipal bonds
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	17	12
Fair Value, Recurring \| Municipal bonds \| Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	0	0
Fair Value, Recurring \| Municipal bonds \| Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	17	12
Fair Value, Recurring \| Municipal bonds \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	$ 0	$ 0

Derivative Liability Statement Of Financial Position Extensible Enumeration Not Disclosed Flag

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- Definition

Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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