MORTGAGE LOAN SALES AND SERVICING RIGHTS - Narrative (Details) - Residential mortgage - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Servicing Assets at Fair Value [Line Items]
Servicing income	$ 24	$ 22
Unpaid principal balance of third party serviced loans	$ 32,500		$ 32,400

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 860
-SubTopic 50
-Name Accounting Standards Codification
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481229/860-50-50-3

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 860
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 860
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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