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

Financing Receivable Impairment Modification Minimum Period

+ References

No definition available.

+ Details

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

- Definition

Funds For Reimbursement Relating To Purchased Manufactured Housing

+ References

No definition available.

+ Details

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

- Definition

Loans Held-for-investment, Purchase Price as a Percentage of Loans Outstanding

+ References

No definition available.

+ Details

Name:	cubi_LoansHeldforinvestmentPurchasePriceasaPercentageofLoansOutstanding
Namespace Prefix:	cubi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Loans Held-for-investment, Term

+ References

No definition available.

+ Details

Name:	cubi_LoansHeldforinvestmentTerm
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

Mortgage Loans on Real Estate, Loans Acquired

+ References

No definition available.

+ Details

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

- 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

The effect of a change in method or methods for calculating the allowance for credit losses on the current period provision.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesEffectOfChangeInMethod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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 within the previous 12 months and for which there was a payment default.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=84173941&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 investment related to financing receivables modified by troubled debt restructurings within the previous 12 months, for which there was a payment default.

+ References

+ Details

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

- Definition

The net gain (loss) resulting from a sale of loans, including adjustments to record loans classified as held-for-sale at the lower-of-cost-or-market and fair value adjustments to loan held for investment purposes.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.13(h))
-URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.3(a))
-URI http://asc.fasb.org/extlink&oid=114873790&loc=SL114874131-224263

+ Details

Name:	us-gaap_GainLossOnSalesOfLoansNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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=84173941&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=84173941&loc=SL49126937-111524

+ Details

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

- Definition

The cash inflow associated with the sale of loans receivables arising from the financing of goods and services.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3179-108585

+ Details

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

- 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_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=cubi_ManufacturedHousingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ResidentialMortgageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=cubi_MultifamilyPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_FederalHomeLoanBankAdvancesBranchOfFHLBBankAxis=srt_FederalHomeLoanBankOfPittsburghMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Loans Receivable and Allowance for Loan Losses - Additional Information (Detail)				3 Months Ended				6 Months Ended
	Jun. 30, 2018 USD ($) Loan Commitment	Dec. 31, 2017 USD ($) Loan	Jun. 30, 2017 USD ($) Loan	Jun. 30, 2018 USD ($) Allowance Commitment	Mar. 31, 2018 USD ($)	Jun. 30, 2017 USD ($) Allowance	Mar. 31, 2017 USD ($)	Jun. 30, 2018 USD ($) Allowance Commitment	Jun. 30, 2017 USD ($) Allowance
Financing Receivable, Modifications [Line Items]
Funds for reimbursement	$ 500,000	$ 600,000		$ 500,000				$ 500,000
Loans reported as TDR	$ 19,400,000	20,400,000		$ 19,400,000				$ 19,400,000
Minimum performance requirement								6 months
Sustained performance period								9 months
Number of commitments to lend additional funds (commitment) \| Commitment	0			0				0
Loans modified as TDR allowance (allowance) \| Allowance				0		0			0
Residential mortgage loans acquired									$ 0
Loans receivable, net of allowance for loan losses	$ 7,143,438,000	6,730,243,000		$ 7,143,438,000				$ 7,143,438,000
Proceeds from sales of loans								29,038,000	112,927,000
Gain on sale of SBA and other loans				$ 947,000		$ 573,000		2,308,000	1,901,000
Term of fixed rate residential mortgage loans				30 years		30 years	30 years
Purchase price as a percentage of loans outstanding				100.40%		101.00%	98.50%
Residential real estate
Financing Receivable, Modifications [Line Items]
Residential real estate held in other real estate owned	300,000			$ 300,000				300,000
Loans in process of foreclosure	2,200,000	$ 1,600,000		2,200,000				2,200,000
Loans receivable, net of allowance for loan losses	$ 277,400,000			277,400,000				$ 277,400,000
Commercial and industrial
Financing Receivable, Modifications [Line Items]
Number of loans modified as TDR (loan) \| Loan	1	1
Loans modified as TDR	$ 1,600,000	$ 2,100,000
Manufactured housing
Financing Receivable, Modifications [Line Items]
Number of loans modified as TDR (loan) \| Loan	0		6
Loans modified as TDR									300,000
Loans modified as TDR allowance (allowance) \| Allowance								1
Allowance for credit losses, effect of change in method								$ 1,000
Small Business Administration Loan
Financing Receivable, Modifications [Line Items]
Loans receivable, net of allowance for loan losses	$ 11,700,000		$ 7,000,000	11,700,000	$ 15,000,000	$ 7,000,000	$ 8,700,000	11,700,000	7,000,000
Gain on sale of SBA and other loans				900,000	$ 1,400,000	600,000	800,000
Residential Mortgage Loan Commitments
Financing Receivable, Modifications [Line Items]
Loans receivable, net of allowance for loan losses			$ 90,000,000			$ 90,000,000	174,200,000		$ 90,000,000
Multi-family
Financing Receivable, Modifications [Line Items]
Loans receivable, net of allowance for loan losses							94,900,000
Proceeds from sales of loans							95,400,000
Gain on sale of SBA and other loans							$ 500,000
Federal Home Loan Bank of Pittsburgh
Financing Receivable, Modifications [Line Items]
Loans pledged as collateral	$ 5,600,000,000	$ 5,500,000,000		$ 5,600,000,000				$ 5,600,000,000