REGULATORY CAPITAL - Narrative (Details) $ in Millions	12 Months Ended
Dec. 31, 2024 USD ($)	Dec. 31, 2023
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Capital conservation buffer	0.0704	0.0775
Basel III conservation buffers, total risk-based capital	0.0250
FCB
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Capital conservation buffer	0.0666	0.0756
Dividend restrictions, additional maximum amount of distribution	$ 7,630
Payments of dividends	$ 2,220

Banking Regulation, Dividend Restrictions, Maximum Additional Amount Of Distribution

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Banking Regulation, Total Risk-Based Capital Ratio, Capital Conservation Buffer

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Banking Regulation, Total Risk-Based Capital Ratio, Conservation Buffer, Minimum

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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.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 942
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477270/942-505-50-1B

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
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-Publisher FASB
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Cash outflow in the form of ordinary dividends to common shareholders, preferred shareholders and noncontrolling interests, generally out of earnings.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
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