Jointly Owned Generation Units (Details)	Dec. 31, 2018 USD ($) MW	Apr. 13, 2016 USD ($)
Jointly Owned Utility Plant Interests [Line Items]
Accumulated depreciation	$ 17,694,000
Utility plant in service	248,897,000
Construction work in progress	5,780,000
RODEMACHER UNIT 2
Jointly Owned Utility Plant Interests [Line Items]
Accumulated depreciation	5,309,000
Utility plant in service	71,962,000
Construction work in progress	$ 317,000
Ownership interest percentage	30.00%
Nameplate capacity (MW) \| MW	523
Ownership interest (MW) \| MW	157
DOLET HILLS
Jointly Owned Utility Plant Interests [Line Items]
Accumulated depreciation	$ 12,385,000
Utility plant in service	176,935,000
Construction work in progress	$ 5,463,000
Ownership interest percentage	50.00%
Nameplate capacity (MW) \| MW	650
Ownership interest (MW) \| MW	325
SUCCESSOR
Jointly Owned Utility Plant Interests [Line Items]
Accumulated depreciation		$ 0
CLECO POWER
Jointly Owned Utility Plant Interests [Line Items]
Accumulated depreciation	$ 309,371,000
Utility plant in service	540,573,000
Construction work in progress	5,780,000
CLECO POWER \| RODEMACHER UNIT 2
Jointly Owned Utility Plant Interests [Line Items]
Accumulated depreciation	79,489,000
Utility plant in service	146,142,000
Construction work in progress	$ 317,000
Ownership interest percentage	30.00%
Nameplate capacity (MW) \| MW	523
Ownership interest (MW) \| MW	157
CLECO POWER \| DOLET HILLS
Jointly Owned Utility Plant Interests [Line Items]
Accumulated depreciation	$ 229,882,000
Utility plant in service	394,431,000
Construction work in progress	$ 5,463,000
Ownership interest percentage	50.00%
Nameplate capacity (MW) \| MW	650
Ownership interest (MW) \| MW	325

The capacity (in megawatts) of the jointly owned generation unit.

No definition available.

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Namespace Prefix:	cnl_
Data Type:	num:powerItemType
Balance Type:	na
Period Type:	instant

- Definition

The entity's ownership interest in the generation unit's name plate capacity (in megawatts).

+ References

No definition available.

+ Details

Name:	cnl_JointlyOwnedUtilityPlantOwnershipShareOfCapacity
Namespace Prefix:	cnl_
Data Type:	num:powerItemType
Balance Type:	na
Period Type:	instant

- Definition

The period end amount owned by the reporting utility of a jointly owned utility plant in service.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 980
-SubTopic 360
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 10.C)
-URI http://asc.fasb.org/extlink&oid=115995737&loc=d3e659983-123033

+ Details

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Namespace Prefix:	us-gaap_
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

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

- Definition

The period end amount of construction work in progress at a jointly owned electricity generation plant.

+ References

+ Details

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

- Definition

The period end amount of accumulated depreciation in a jointly owned electricity generation plant.

+ References

+ Details

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

- Definition

The proportionate share of interest (percent) in a jointly owned utility plant.

+ References

+ 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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- Details

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Namespace Prefix:
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Balance Type:
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- Details

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Namespace Prefix:
Data Type:	na
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- Details

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Namespace Prefix:
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Balance Type:
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