LEASES - Lessor, Lease Receivables and Investment in Operating Leases and their Corresponding Balance Sheet Location (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Direct financing and sales-type leases
Lease receivables	$ 258,481	$ 251,507
Guaranteed residual assets	27,732	24,045
Unguaranteed residual assets	11,490	10,463
Deferred initial direct costs	1,426	1,352
Unearned income	(26,996)	(24,673)
Net investment in direct financing and sales-type leases	272,133	262,694
Operating leases
Investment in operating leases	358,600	308,993
Accumulated depreciation	(100,211)	(95,053)
Deferred initial direct costs	994	978
Net investment in operating leases	259,383	214,918
Total lease assets	$ 531,516	$ 477,612

Direct Financing Lease, Deferred Initial Direct Costs

No definition available.

Name:	cubi_DirectFinancingLeaseDeferredInitialDirectCosts
Namespace Prefix:	cubi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Net Investment in Direct Financing and Operating Leases

+ References

No definition available.

+ Details

Name:	cubi_NetInvestmentinDirectFinancingandOperatingLeases
Namespace Prefix:	cubi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Operating Lease, Deferred Initial Direct Costs

+ References

No definition available.

+ Details

Name:	cubi_OperatingLeaseDeferredInitialDirectCosts
Namespace Prefix:	cubi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Operating Lease, Investment in Lease, Gross

+ References

No definition available.

+ Details

Name:	cubi_OperatingLeaseInvestmentinLeaseGross
Namespace Prefix:	cubi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Operating Lease, Net Investment in Lease

+ References

No definition available.

+ Details

Name:	cubi_OperatingLeaseNetInvestmentinLease
Namespace Prefix:	cubi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(8)(b))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(14))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482099/360-10-50-1

+ Details

Name:	us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of deferred selling profit from direct financing lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479773/842-30-50-6

+ Details

Name:	us-gaap_DirectFinancingLeaseDeferredSellingProfit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Present value of lease payments not yet received by lessor and amount expected to be derived from underlying asset, following end of lease term, guaranteed by lessee or other third party unrelated to lessor, from direct financing lease.

+ References

+ Details

Name:	us-gaap_DirectFinancingLeaseLeaseReceivable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount excluding accrued interest, before allowance for credit loss, of net investment in direct financing lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479344/326-20-45-1

+ Details

Name:	us-gaap_DirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestBeforeAllowanceForCreditLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_DirectFinancingLeaseNetInvestmentInLeasesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of residual asset covered by residual value guarantee under direct financing lease. Excludes guarantee considered to be lease payments for lessor.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479773/842-30-50-3

+ Details

Name:	us-gaap_DirectFinancingLeaseResidualValueOfLeasedAsset
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Present value expected to be derived from underlying asset, following end of lease term, not guaranteed by lessee or other third party unrelated to lessor.

+ References

+ Details

Name:	us-gaap_DirectFinancingLeaseUnguaranteedResidualAsset
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_LessorOperatingLeaseDescriptionAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration