PREMISES, EQUIPMENT, AND SOFTWARE - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Capital Leases of Lessee [Abstract]
Depreciation expense	$ 115	$ 107	$ 98
Capitalized Software
Capitalized software, gross	2,600	2,600
Capitalized software, accumulated amortization	1,700	1,700
Amortization of software	$ 254	$ 243	$ 235

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- Definition

For each balance sheet presented, the amount of accumulated amortization for capitalized computer software costs.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 985
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481283/985-20-50-1

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Amount of expense for amortization of capitalized computer software costs.

+ References

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-Topic 985
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
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- Definition

Amount before accumulated amortization of capitalized costs for computer software, including but not limited to, acquired and internally developed computer software.

+ References

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- References

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- Definition

The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
-Subparagraph (b)
-SubTopic 10
-Topic 230
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