The additional minimum amount the entity agreed to spend under the long-term purchase commitment.

No definition available.

Name:	crtn_AdditionalLongTermPurchaseCommitmentAmount
Namespace Prefix:	crtn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Long-Term Purchase Commitment, Additional Period

+ References

No definition available.

+ Details

Name:	crtn_LongTermPurchaseCommitmentAdditionalPeriod
Namespace Prefix:	crtn_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The balance of the amount the entity agreed to spend under the long-term purchase commitment.

+ References

No definition available.

+ Details

Name:	crtn_LongTermPurchaseCommitmentAmountOutstanding
Namespace Prefix:	crtn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of liability recognized arising from contingent consideration in a business combination, expected to be settled within one year or the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 35
-Paragraph 1
-Subparagraph b
-URI http://asc.fasb.org/extlink&oid=6911338&loc=d3e6819-128478

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 25
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6911189&loc=d3e6408-128476

+ Details

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

- Definition

The minimum amount the entity agreed to spend under the long-term purchase commitment.

+ References

No definition available.

+ Details

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

- Definition

Period covered by the long-term purchase commitment, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_LongtermPurchaseCommitmentPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis=us-gaap_ComputerSoftwareIntangibleAssetMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

COMMITMENTS AND CONTINGENCIES (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Apr. 02, 2016	Apr. 04, 2015	Dec. 30, 2017	Dec. 31, 2016
Purchase Commitment [Line Items]
Earn-Out Liability			$ 0	$ 1,903
Software [Member]
Purchase Commitment [Line Items]
Purchase commitment amount		$ 412
Purchase commitment period		3 years
Additional purchase commitment amount	$ 95
Purchase commitment, additional period	2 years
Purchase obligation remaining				$ 181