v3.25.1

OTHER ASSETS - Narrative (Details) $ in Millions	3 Months Ended
OTHER ASSETS - Narrative (Details) $ in Millions	Mar. 31, 2025 USD ($) option	Mar. 31, 2024 USD ($)
Lessee, Lease, Description [Line Items]
Number of options to renew \| option	1
Operating lease expense	$ 36.8	$ 34.1
Sublease income	$ 0.8	$ 0.9
Minimum
Lessee, Lease, Description [Line Items]
Renewal term (in years)	1 year
Maximum
Lessee, Lease, Description [Line Items]
Renewal term (in years)	5 years

Lessee, Operating Leases, Number Of Options To Renew

+ References

No definition available.

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- Definition

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/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 7A
-Subparagraph (c)
-Publisher FASB
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- Definition

Term of lessee's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-3

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- Definition

Amount of operating lease expense. Excludes sublease income.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 4
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479041/842-20-45-4

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- Definition

Amount of sublease income excluding finance and operating lease expense.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
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Santander Holdings USA, Inc. 10-Q