Financing Receivable Impairment Minimum Performance Requirement Period

No definition available.

Name:	cubi_FinancingReceivableImpairmentMinimumPerformanceRequirementPeriod
Namespace Prefix:	cubi_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Loans Held For Sale Average Life From Purchase To Sale

+ References

No definition available.

+ Details

Name:	cubi_LoansHeldForSaleAverageLifeFromPurchaseToSale
Namespace Prefix:	cubi_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Loans Receivables Gross Troubled Debt Restructurings

+ References

No definition available.

+ Details

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

- Definition

Number Of Commitments To Lend Additional Funds For Troubled Debt Restructurings

+ References

No definition available.

+ Details

Name:	cubi_NumberOfCommitmentsToLendAdditionalFundsForTroubledDebtRestructurings
Namespace Prefix:	cubi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Other Real Estate And Foreclosed Assets, Residential

+ References

No definition available.

+ Details

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

- Definition

Specific Allowance, Loans Modified In Troubled Debt Restructurings

+ References

No definition available.

+ Details

Name:	cubi_SpecificAllowanceLoansModifiedInTroubledDebtRestructurings
Namespace Prefix:	cubi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Specific Allowance, Loans Modified In Troubled Debt Restructurings, Amount

+ References

No definition available.

+ Details

Name:	cubi_SpecificAllowanceLoansModifiedInTroubledDebtRestructuringsAmount
Namespace Prefix:	cubi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Specific Allowance, Loans Modified In Troubled Debt Restructurings, Loans

+ References

No definition available.

+ Details

Name:	cubi_SpecificAllowanceLoansModifiedInTroubledDebtRestructuringsLoans
Namespace Prefix:	cubi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- 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

No definition available.

+ Details

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

- Definition

Number of financing receivables that have been modified by troubled debt restructurings.

+ References

+ Details

Name:	us-gaap_FinancingReceivableModificationsNumberOfContracts2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after troubled debt restructuring, of modified financing receivable.

+ References

+ Details

Name:	us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of financing receivable modified as troubled debt restructuring.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953676-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=118939409&loc=d3e18845-111554

+ Details

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

- Definition

Number of financing receivable contracts modified as troubled debt restructuring within previous 12 months, with subsequent payment default.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953682-111524

+ Details

Name:	us-gaap_FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of financing receivable modified as troubled debt restructuring within previous 12 months, with subsequent payment default.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953682-111524

+ Details

Name:	us-gaap_FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums over and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes loans and leases covered under loss sharing agreements.

+ References

No definition available.

+ Details

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

- Definition

Carrying amount as of the balance sheet date of loans that have been pledged as collateral for borrowings. If the secured party has the right by contract or custom to sell or re-pledge the collateral, then the debtor reclassifies that asset and report that asset in its statement of financial position separately from other assets not so encumbered.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66007379&loc=d3e113888-111728

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5086-111524

+ Details

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

- Definition

Recorded investment of consumer mortgage loan receivables secured by residential real estate properties for which formal foreclosure proceedings are in process.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 35
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL49126937-111524

+ Details

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

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_ResidentialRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=cubi_CommercialandIndustrialMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=us-gaap_PrincipalForgivenessMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Loans and Leases Receivable and Allowance for Loan and Lease Losses - Additional Information (Detail)		3 Months Ended		9 Months Ended
	Dec. 31, 2018 USD ($) Loan	Sep. 30, 2019 USD ($) Commitment Loan	Sep. 30, 2018 USD ($) Loan Allowance	Sep. 30, 2019 USD ($) Commitment Loan	Sep. 30, 2018 USD ($) Loan Allowance
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans held for sale, average life from purchase to sale				30 days
Loans reported as TDR	$ 19,200,000	$ 13,500,000		$ 13,500,000
Lease receivable, TDR	0	$ 0		$ 0
Minimum performance requirement				9 months
Number of loans \| Loan		7	8	21	33
Recorded investment		$ 196,000	$ 473,000	$ 1,142,000	$ 1,458,000
Number of loans modified as TDR (loan) \| Loan				4	0
Number of commitments to lend additional funds (commitment) \| Commitment		0		0
Loans modified as TDR				$ 158,000	$ 0
Loans modified as TDR allowance, amount		$ 3,000		$ 6,000
Loans modified as TDR (loans) \| Loan		4		9
Loans modified as TDR allowance (allowance) \| Allowance			0		0
Loans and leases receivable, net of allowance for loan and lease losses	8,503,522,000	$ 9,723,714,000		$ 9,723,714,000
Loans pledged as collateral	5,400,000,000	5,200,000,000		5,200,000,000
Residential real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Residential real estate held in other real estate owned	200,000	200,000		200,000
Loans in process of foreclosure	$ 2,100,000	$ 800,000		$ 800,000
Commercial and industrial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of loans modified as TDR (loan) \| Loan	1
Loans modified as TDR	$ 1,500,000
Forgiveness of debt
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of loans \| Loan		0	0	0	0