v3.22.0.1

Portfolio Loans Receivable - Allowance for Loan Losses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	$ 23,434
Provision for loan losses	3,359	$ 11,242
Charge-Offs	(1,654)	(1,166)
Recoveries	42	57
Ending Balance	25,181	23,434
Allowance for Loan Losses Ending Balance Evaluated for Impairment - Individually	218	253
Allowance for Loan Losses Ending Balance Evaluated for Impairment - Collectively	24,963	23,181
Outstanding Loan Balances Evaluated for Impairment - Individually	11,339	9,963
Outstanding Loan Balances Evaluated for Impairment - Collectively	1,519,863	1,306,313
Residential | Real estate:
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	7,153	4,135
Provision for loan losses	(1,541)	3,018
Charge-Offs	0	0
Recoveries	0	0
Ending Balance	5,612	7,153
Allowance for Loan Losses Ending Balance Evaluated for Impairment - Individually	0	0
Allowance for Loan Losses Ending Balance Evaluated for Impairment - Collectively	5,612	7,153
Outstanding Loan Balances Evaluated for Impairment - Individually	2,835	4,687
Outstanding Loan Balances Evaluated for Impairment - Collectively	398,772	433,173
Commercial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	2,417	1,548
Provision for loan losses	253	1,102
Charge-Offs	(39)	(233)
Recoveries	6	0
Ending Balance	2,637	2,417
Allowance for Loan Losses Ending Balance Evaluated for Impairment - Individually	218	253
Allowance for Loan Losses Ending Balance Evaluated for Impairment - Collectively	2,419	2,164
Outstanding Loan Balances Evaluated for Impairment - Individually	676	1,182
Outstanding Loan Balances Evaluated for Impairment - Collectively	175,280	155,945
Commercial | Real estate:
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	6,786	3,572
Provision for loan losses	1,941	3,214
Charge-Offs	(161)	0
Recoveries	0	0
Ending Balance	8,566	6,786
Allowance for Loan Losses Ending Balance Evaluated for Impairment - Individually	0	0
Allowance for Loan Losses Ending Balance Evaluated for Impairment - Collectively	8,566	6,786
Outstanding Loan Balances Evaluated for Impairment - Individually	25	2,358
Outstanding Loan Balances Evaluated for Impairment - Collectively	556,314	390,192
Construction | Real estate:
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	4,595	2,668
Provision for loan losses	103	2,216
Charge-Offs	0	(296)
Recoveries	1	7
Ending Balance	4,699	4,595
Allowance for Loan Losses Ending Balance Evaluated for Impairment - Individually	0	0
Allowance for Loan Losses Ending Balance Evaluated for Impairment - Collectively	4,699	4,595
Outstanding Loan Balances Evaluated for Impairment - Individually	7,803	1,736
Outstanding Loan Balances Evaluated for Impairment - Collectively	247,344	223,168
Consumer | Credit card, net of reserve
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	2,462	1,368
Provision for loan losses	2,612	1,681
Charge-Offs	(1,454)	(637)
Recoveries	35	50
Ending Balance	3,655	2,462
Allowance for Loan Losses Ending Balance Evaluated for Impairment - Individually	0	0
Allowance for Loan Losses Ending Balance Evaluated for Impairment - Collectively	3,655	2,462
Outstanding Loan Balances Evaluated for Impairment - Individually	0	0
Outstanding Loan Balances Evaluated for Impairment - Collectively	141,120	102,186
Consumer | Other consumer
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	21	10
Provision for loan losses	(9)	11
Charge-Offs	0	0
Recoveries	0	0
Ending Balance	12	21
Allowance for Loan Losses Ending Balance Evaluated for Impairment - Individually	0	0
Allowance for Loan Losses Ending Balance Evaluated for Impairment - Collectively	12	21
Outstanding Loan Balances Evaluated for Impairment - Individually	0	0
Outstanding Loan Balances Evaluated for Impairment - Collectively	$ 1,033	$ 1,649

X

- 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

X

- Definition

Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

+ 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)(3)
-URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953423-111524

+ Details

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

X

- Definition

Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

+ 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)(1)
-URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953423-111524

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(7)(2))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124255206&loc=SL82895884-210446

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919249-210447

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919249-210447

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph (a)
-Subparagraph (3)

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph (c)

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph (a)
-Subparagraph (1)

+ Details

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

X

- Definition

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

+ 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 (g)
-URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953423-111524

+ Details

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

X

- Definition

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

+ 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 (g)
-URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953423-111524

+ Details

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

X

- Definition

Amount of increase in allowance for credit loss on financing receivable from recovery.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 55
-Paragraph 79
-URI http://asc.fasb.org/extlink&oid=124267575&loc=SL82922352-210448

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919249-210447

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(4)
-URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953423-111524

+ Details

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

X

- Definition

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

+ 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 (h)
-URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953423-111524

+ Details

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

X

- Definition

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

+ 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 (h)
-URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953423-111524

+ Details

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

X

- Definition

Amount of credit loss expense (reversal of expense) for financing receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919249-210447

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-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=120399700&loc=SL114874048-224260

+ Details

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

X

- Details

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

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_RealEstateLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

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

X

- Details

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

X

- Details

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

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_CreditCardReceivablesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=cbnk_OtherConsumerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: