Affiliate Transactions - Summary of Revenue Received From Affiliates (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Affiliate Transaction [Line Items]
Affiliate revenue	$ 0	$ 0	$ 0
Cleco Power
Affiliate Transaction [Line Items]
Affiliate revenue	5,156	3,125	874
Total	11,619	10,745	1,966
Cleco Cajun \| Cleco Power
Affiliate Transaction [Line Items]
Other operations revenue	6,463	7,471	0
Affiliate revenue	441	37	0
Support Group \| Cleco Power
Affiliate Transaction [Line Items]
Affiliate revenue	4,715	3,088	874
Cleco Holdings \| Cleco Power
Affiliate Transaction [Line Items]
Other income	$ 0	$ 149	$ 1,092

Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07.1(c))
-URI http://asc.fasb.org/extlink&oid=120401555&loc=SL114874292-224272

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1(e))
-URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227

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