Fair Value Measurements (Details) - USD ($)	3 Months Ended	12 Months Ended
May 05, 2018	Apr. 29, 2017	Feb. 03, 2018
Fair value measurements
Impairment charge	$ 0	$ 70,000
Fair Value, Measurements, Nonrecurring
Fair value measurements
Carrying value	0		$ 318,000
Impairment charge	0		318,000
Fair Value, Measurements, Nonrecurring \| Level 3
Fair value measurements
Fair value measured using Level 3 inputs	$ 0		$ 0

Represents the carrying amount of long-lived assets which are held and used for normal operations of business and not for sale.

No definition available.

+ Details

Name:	cbk_LongLivedAssetsHeldAndUsedCarryingAmount
Namespace Prefix:	cbk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the fair value of long-lived assets which are held and used for normal operations of business and not for sale.

+ References

No definition available.

+ Details

Name:	cbk_LongLivedAssetsHeldAndUsedFairValue
Namespace Prefix:	cbk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

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

- Definition

The charge against earnings resulting from the aggregate write down of tangible assets from their carrying value to their fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84176398&loc=d3e2921-110230

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=64827811&loc=d3e1361-107760

+ Details

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

- Details

Name:	us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsNonrecurringMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: