DISCONTINUED OPERATIONS, SIGNIFICANT DISPOSALS AND OTHER BUSINESS EXITS (Details) shares in Millions, $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2025 USD ($) business	Jun. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($) business	Sep. 30, 2024 USD ($)	Sep. 24, 2025 shares
Banamex
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percentage owned of equity investment						25.00%
Equity method investment sold (in shares) | shares						520
Price to book value						0.80
Consumer banking businesses
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of businesses with sale agreements | business	9			9
Poland Consumer Banking Business | Held for sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on sale	$ 184	$ 184
Loss on sale after tax	155	$ 155
Income before taxes	28		$ 41	$ 97	$ 111
Cash and deposits with banks	4,671			4,671
Loans (net of allowance of $25 at September 30, 2025)	1,679			1,679
Allowance	25			25
Other assets	50			50
Total assets	6,400			6,400
Deposits	6,085			6,085
Other liabilities	64			64
Total liabilities	6,149			6,149
Deposits with banks	$ 4,600			$ 4,600