Acquired Finite-Lived Intangible Liabilities, Residual Value

No definition available.

Name:	cnl_AcquiredFiniteLivedIntangibleLiabilitiesResidualValue
Namespace Prefix:	cnl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Acquired Finite-Lived Intangible Liabilities, Weighted Average Useful Life

+ References

No definition available.

+ Details

Name:	cnl_AcquiredFiniteLivedIntangibleLiabilitiesWeightedAverageUsefulLife
Namespace Prefix:	cnl_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Intangible Liabilities

+ References

No definition available.

+ Details

Name:	cnl_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleLiabilities
Namespace Prefix:	cnl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Finite-Lived Intangible Liabilities, Net

+ References

No definition available.

+ Details

Name:	cnl_FiniteLivedIntangibleLiabilitiesNet
Namespace Prefix:	cnl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The aggregate expected value at the end of their useful life of a major finite-lived intangible asset class acquired during the period either individually or as part of a group of assets (in either an asset acquisition or business combination). A major class is composed of intangible assets that can be grouped together because they are similar, either by their nature or by their use in the operations of a company.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275

+ Details

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

- Definition

Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275

+ Details

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

- Definition

The amount of identifiable intangible assets recognized as of the acquisition date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 55
-Paragraph 37
-URI http://asc.fasb.org/extlink&oid=108330185&loc=d3e2207-128464

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84161108&loc=d3e4845-128472

+ Details

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

- Definition

Useful life of finite-lived intangible assets, 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_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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_FiniteLivedIntangibleAssetsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of increase in assets, excluding financial assets, lacking physical substance with a definite life, from an acquisition.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275

+ Details

Name:	us-gaap_FinitelivedIntangibleAssetsAcquired1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	cnl_FiniteLivedIntangibleLiabilitiesByMajorClassAxis=cnl_PowerSupplyAgreementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cnl_FiniteLivedIntangibleLiabilitiesByMajorClassAxis=cnl_LongTermServiceAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_TradeNamesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=cnl_PowerSupplyAgreementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=cnl_ClecoKatrinaRitaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=cnl_RightToBillAndCollectStormRecoveryChargesFromCustomersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=cnl_RighttobillandcollectstormrecoverychargesfromcustomersnetoffinancingcostsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=cnl_FinancingCostsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Intangible Assets and Liabilities - Narrative (Details) - USD ($)		6 Months Ended	12 Months Ended
	Feb. 04, 2019	Jun. 30, 2019	Dec. 31, 2008	Dec. 31, 2016
Power supply agreements
Finite-Lived Intangible Assets [Line Items]
Intangible liabilities, residual value		$ 0
Preliminary fair value of intangible liabilities	$ 14,200,000
Intangible liabilities, remaining life		6 years
LTSA
Finite-Lived Intangible Assets [Line Items]
Intangible liabilities	$ 24,100,000
Intangible liabilities, remaining life	7 years
Trade name
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life		20 years
Intangible assets, residual value		$ 0
Power supply agreements
Finite-Lived Intangible Assets [Line Items]
Intangible assets, residual value	$ 0	$ 0
Preliminary fair value of intangible assets	$ 98,900,000
Power supply agreements \| Minimum
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life		4 years
Intangible assets, remaining life	2 years
Power supply agreements \| Maximum
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life		16 years
Intangible assets, remaining life	8 years
Cleco Katrina/Rita
Finite-Lived Intangible Assets [Line Items]
Intangible assets, residual value		$ 0
Accumulated amortization				$ 0
Cleco Katrina/Rita \| Cleco Katrina/Rita right to bill and collect storm recovery charges
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets acquired			$ 177,500,000
Cleco Katrina/Rita \| Cleco Katrina/Rita right to bill and collect storm recovery charges \| Minimum
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life			12 years
Cleco Katrina/Rita \| Cleco Katrina/Rita right to bill and collect storm recovery charges \| Maximum
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life			15 years
Cleco Katrina/Rita \| Cleco Katrina/Rita right to bill and collect storm recovery charges from customers, net of financing costs
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets acquired			$ 176,000,000
Cleco Katrina/Rita \| Financing costs
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets acquired			$ 1,500,000