The additional area of rental space in connection with the amendment of lease agreement.

No definition available.

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Namespace Prefix:	clfd_
Data Type:	num:areaItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of options to renew an operating lease.

+ References

No definition available.

+ Details

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Namespace Prefix:	clfd_
Data Type:	xbrli:integerItemType
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Period Type:	instant

- Definition

The amount of termination fee pursuant to the lease agreement.

+ References

No definition available.

+ Details

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Namespace Prefix:	clfd_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Area of a real estate property.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:areaItemType
Balance Type:	na
Period Type:	instant

- Definition

Term of lessee's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918673-209980

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

Term of lessee's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

+ Details

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of cash outflow from operating lease, excluding payments to bring another asset to condition and location necessary for its intended use.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 5
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121603541&loc=SL77918643-209977

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (g)(1)
-URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918686-209980

+ Details

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

- Definition

Weighted average discount rate for operating lease calculated at point in time.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (g)(4)
-URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918686-209980

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 55
-Paragraph 53
-URI http://asc.fasb.org/extlink&oid=121568110&loc=SL77918982-209971

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

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Namespace Prefix:
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Balance Type:
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- Details

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Namespace Prefix:
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Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=clfd_TijuanaMexicoMember
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Note 10 - Leases (Details Textual)		3 Months Ended	9 Months Ended
Note 10 - Leases (Details Textual)	Jun. 30, 2019 ft²	Jun. 30, 2020 USD ($) ft²	Jun. 30, 2020 USD ($) ft²	Feb. 12, 2020 ft²	Aug. 01, 2017 ft²	Jan. 01, 2015
Operating Lease, Weighted Average Discount Rate, Percent		3.48%	3.48%
Operating Lease, Payments \| $		$ 237,726	$ 574,381
Weighted Average [Member]
Lessee, Operating Lease, Term of Contract (Year)		4 years 2 months 15 days	4 years 2 months 15 days
7050 Winnetka Avenue North, Brooklyn Park, Minnesota [Member]
Area of Real Estate Property (Square Foot)		71,000	71,000
Lessee, Operating Lease, Term of Contract (Year)						10 years 2 months 1 day
Additional area of rental space (Square Foot)	14,000
Operating Lease Termination Fee \| $			$ 249,000
Tijuana, Mexico [Member]
Area of Real Estate Property (Square Foot)					46,000
Lessee, Operating Lease, Term of Contract (Year)					3 years
Tijuana, Mexico 2 [Member]
Area of Real Estate Property (Square Foot)				52,000
Lessee, Operating Lease, Term of Contract (Year)				42 months
Lessee, Operating Lease, Number of Options to Renew				2
Lessee, Operating Lease, Renewal Term (Year)				3 years