Allowance for Loan and Lease Losses, Adjustments, Net [Abstract] [Roll Forward]

No definition available.

Name:	cubi_AllowanceforLoanandLeaseLossesAdjustmentsNetAbstractRollForward
Namespace Prefix:	cubi_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Loans and Leases Receivable that are either specifically or collectively evaluated for impairment

+ References

No definition available.

+ Details

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

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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

- References

No definition available.

+ Details

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

- Definition

A valuation allowance for financing receivables that are expected to be uncollectible.

+ References

+ Details

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

- Definition

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

+ References

+ Details

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

- Definition

Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

+ References

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of recovery of financing receivables doubtful of collection that were previously charged off.

+ References

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of direct write-downs of financing receivables charged against the allowance.

+ References

+ Details

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

- Definition

The balance of financing receivables that were collectively evaluated for impairment.

+ References

+ Details

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

- Definition

The balance of financing receivables that were individually evaluated for impairment.

+ References

+ Details

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

- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(d))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (b)(1)(ii)
-URI http://asc.fasb.org/extlink&oid=82894903&loc=d3e15032-111544

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SAB Topic 6.L.1)
-URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74567-122707

+ Details

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

- Definition

Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522

+ Details

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

- Definition

Net amount of the investment in a contractual right to receive money on demand or on fixed or determinable dates that is recognized as an asset in the creditor's statement of financial position. Examples include, but are not limited to, credit card receivables, notes receivable and receivables relating to lessor's rights to payments from leases other than operating leases that have been recorded as assets. Excludes trade accounts receivable with contractual maturity of one year or less and arose from the sale of goods or services.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.3)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value.

+ 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 (c)(2)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.11)
-URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

+ Details

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

- Details

Name:	us-gaap_CreditLossStatusAxis=us-gaap_FinancialAssetAcquiredWithCreditDeteriorationMember
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:	us-gaap_FinancingReceivablePortfolioSegmentAxis=cubi_CommercialAndIndustrialExcludingCommercialRealEstateOwnerOccupiedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

Loans and Leases Receivable and Allowance for Loan and Lease Losses - Schedule of Allowance for Loan and Lease Losses (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Dec. 31, 2018
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 39,972	$ 38,015
Charge-offs	(1,344)	(689)
Recoveries	284	56
Provision for loan and lease losses	4,767	2,117
Ending balance	43,679	39,499
Loans:
Individually evaluated for impairment			$ 39,359	$ 39,118
Collectively evaluated for impairment			7,207,765	7,077,806
Loans and leases receivable, gross			7,267,246	7,138,498
Loans receivable, at amortized cost or lower of cost or market			7,267,246	7,138,498
Allowance for loan losses:
Individually evaluated for impairment			380	845
Collectively evaluated for impairment			40,469	36,249
Total Allowance for loan losses	39,972	38,015	43,679	39,972
Purchased Credit Impaired Loans
Loans:
Loans acquired with credit deterioration			20,122	21,574
Loans and leases receivable, gross			20,122	21,574
Allowance for loan losses:
Loans acquired with credit deterioration			2,830	2,878
Multi-family
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	11,462	12,168
Charge-offs	(541)	0
Recoveries	0	0
Provision for loan and lease losses	(291)	377
Ending balance	10,630	12,545
Loans:
Individually evaluated for impairment			1,997	1,155
Collectively evaluated for impairment			3,208,673	3,282,452
Loans and leases receivable, gross			3,212,312	3,285,297
Allowance for loan losses:
Individually evaluated for impairment			0	539
Collectively evaluated for impairment			10,630	10,923
Total Allowance for loan losses	11,462	12,168	10,630	11,462
Multi-family \| Purchased Credit Impaired Loans
Loans:
Loans acquired with credit deterioration			1,642	1,690
Loans and leases receivable, gross			1,642	1,690
Allowance for loan losses:
Loans acquired with credit deterioration			0	0
Commercial and industrial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	12,145	10,918
Charge-offs	0	(50)
Recoveries	119	35
Provision for loan and lease losses	383	834
Ending balance	12,647	11,737
Loans:
Individually evaluated for impairment			17,411	17,828
Collectively evaluated for impairment			1,437,764	1,355,436
Loans and leases receivable, gross			1,455,592	1,373,800
Allowance for loan losses:
Individually evaluated for impairment			263	261
Collectively evaluated for impairment			12,116	11,516
Total Allowance for loan losses	12,145	10,918	12,647	12,145
Commercial and industrial \| Purchased Credit Impaired Loans
Loans:
Loans acquired with credit deterioration			417	536
Loans and leases receivable, gross			417	536
Allowance for loan losses:
Loans acquired with credit deterioration			268	368
Commercial real estate owner occupied
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	3,320	3,232
Charge-offs	(8)	(18)
Recoveries	128	0
Provision for loan and lease losses	(15)	311
Ending balance	3,425	3,525
Loans:
Individually evaluated for impairment			867	1,069
Collectively evaluated for impairment			573,918	567,970
Loans and leases receivable, gross			582,637	577,477
Allowance for loan losses:
Individually evaluated for impairment			36	1
Collectively evaluated for impairment			3,389	3,319
Total Allowance for loan losses	3,425	3,232	3,425	3,320
Commercial real estate owner occupied \| Purchased Credit Impaired Loans
Loans:
Loans acquired with credit deterioration			7,852	8,438
Loans and leases receivable, gross			7,852	8,438
Allowance for loan losses:
Loans acquired with credit deterioration			0	0
Commercial real estate non-owner occupied
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	6,093	7,437
Charge-offs	0	0
Recoveries	0	0
Provision for loan and lease losses	(78)	(204)
Ending balance	6,015	7,233
Loans:
Individually evaluated for impairment			102	129
Collectively evaluated for impairment			1,103,105	1,120,633
Loans and leases receivable, gross			1,107,336	1,125,106
Allowance for loan losses:
Individually evaluated for impairment			0	0
Collectively evaluated for impairment			4,019	4,161
Total Allowance for loan losses	6,015	7,437	6,015	6,093
Commercial real estate non-owner occupied \| Purchased Credit Impaired Loans
Loans:
Loans acquired with credit deterioration			4,129	4,344
Loans and leases receivable, gross			4,129	4,344
Allowance for loan losses:
Loans acquired with credit deterioration			1,996	1,932
Construction
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	624	979
Charge-offs	0	0
Recoveries	6	11
Provision for loan and lease losses	(46)	(69)
Ending balance	584	921
Loans:
Individually evaluated for impairment			0	0
Collectively evaluated for impairment			53,372	56,491
Loans and leases receivable, gross			53,372	56,491
Allowance for loan losses:
Individually evaluated for impairment			0	0
Collectively evaluated for impairment			584	624
Total Allowance for loan losses	584	979	584	624
Construction \| Purchased Credit Impaired Loans
Loans:
Loans acquired with credit deterioration			0	0
Loans and leases receivable, gross			0	0
Allowance for loan losses:
Loans acquired with credit deterioration			0	0
Residential real estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	3,654	2,929
Charge-offs	(40)	(365)
Recoveries	7	7
Provision for loan and lease losses	2,951	608
Ending balance	6,572	3,179
Loans:
Individually evaluated for impairment			8,567	8,631
Collectively evaluated for impairment			612,493	553,593
Loans and leases receivable, gross			625,066	566,561
Allowance for loan losses:
Individually evaluated for impairment			78	41
Collectively evaluated for impairment			6,105	3,227
Total Allowance for loan losses	3,654	2,929	6,572	3,654
Residential real estate \| Purchased Credit Impaired Loans
Loans:
Loans acquired with credit deterioration			4,006	4,337
Loans and leases receivable, gross			4,006	4,337
Allowance for loan losses:
Loans acquired with credit deterioration			389	386
Manufactured housing
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	145	180
Charge-offs	0	0
Recoveries	0	0
Provision for loan and lease losses	(28)	(4)
Ending balance	117	176
Loans:
Individually evaluated for impairment			10,307	10,195
Collectively evaluated for impairment			65,601	67,528
Loans and leases receivable, gross			77,778	79,731
Allowance for loan losses:
Individually evaluated for impairment			3	3
Collectively evaluated for impairment			89	89
Total Allowance for loan losses	145	180	117	145
Manufactured housing \| Purchased Credit Impaired Loans
Loans:
Loans acquired with credit deterioration			1,870	2,008
Loans and leases receivable, gross			1,870	2,008
Allowance for loan losses:
Loans acquired with credit deterioration			25	53
Other
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	2,529	172
Charge-offs	(755)	(256)
Recoveries	24	3
Provision for loan and lease losses	1,891	264
Ending balance	3,689	183
Loans:
Individually evaluated for impairment			108	111
Collectively evaluated for impairment			152,839	73,703
Loans and leases receivable, gross			153,153	74,035
Allowance for loan losses:
Individually evaluated for impairment			0	0
Collectively evaluated for impairment			3,537	2,390
Total Allowance for loan losses	$ 2,529	$ 172	3,689	2,529
Other \| Purchased Credit Impaired Loans
Loans:
Loans acquired with credit deterioration			206	221
Loans and leases receivable, gross			206	221
Allowance for loan losses:
Loans acquired with credit deterioration			$ 152	$ 139