The amount of unrealized gains (losses) from the net mark-to-market impact relating to open natural gas positions or FTRs.

No definition available.

+ Details

Name:	cnl_DerivativeUnrealizedGainLossOnDerivativeNet
Namespace Prefix:	cnl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5618551-113959

+ Details

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

- Definition

Amount of increase in the fair value of derivatives recognized in the income statement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5618551-113959

+ Details

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

- Definition

Amount of decrease in the fair value of derivatives recognized in the income statement.

+ References

+ Details

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

- References

No definition available.

+ Details

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

- Details

Name:	us-gaap_HedgingDesignationAxis=us-gaap_NondesignatedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_PriceRiskDerivativeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BalanceSheetLocationAxis=cnl_AccumulatedDeferredFuelMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_IncomeStatementLocationAxis=cnl_ElectricoperationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=cnl_PowerPurchasedForUtilityCustomersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=cnl_FuelUsedForElectricGenerationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Fair Value Accounting - Amount of Gain (Loss) Recognized in Income on Derivatives (Details) - DERIVATIVES NOT DESIGNATED AS HEDGING INSTRUMENTS - Commodity-related contracts - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Commodity-related contracts
Net gain (loss) recognized in income on derivatives	$ 22,557	$ 2,823	$ 27,724	$ 115
Accumulated deferred fuel
Commodity-related contracts
Unrealized gains (losses) associated with FTRs	400	(1,700)	1,400	(3,600)
CLECO POWER
Commodity-related contracts
Net gain (loss) recognized in income on derivatives	687	169	1,865	7,600
CLECO POWER \| Accumulated deferred fuel
Commodity-related contracts
Unrealized gains (losses) associated with FTRs	400	(1,700)	1,400	(3,600)
Electric operations
Commodity-related contracts
Gain recognized in income on derivatives	3,013	1,997	6,262	12,396
Electric operations \| CLECO POWER
Commodity-related contracts
Gain recognized in income on derivatives	3,013	1,997	6,262	12,400
Purchased power
Commodity-related contracts
Loss recognized in income on derivatives	(763)	(2,648)	(1,053)	(12,985)
Purchased power \| CLECO POWER
Commodity-related contracts
Loss recognized in income on derivatives	(2,326)	(1,828)	(4,397)	(4,800)
Fuel used for electric generation
Commodity-related contracts
Gain recognized in income on derivatives	$ 20,307	$ 3,474	$ 22,515	$ 704