Intangible Assets, Intangible Liabilities, and Goodwill - Narrative (Details) - USD ($)		12 Months Ended
	Feb. 04, 2019	Dec. 31, 2020	Dec. 31, 2008	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Apr. 13, 2016
Acquired Finite-Lived Intangible Assets [Line Items]
Residual value				$ 0
Goodwill		$ 1,490,797,000			$ 1,490,797,000	$ 1,490,797,000	$ 1,490,000,000
CLECO POWER
Acquired Finite-Lived Intangible Assets [Line Items]
Impairment of goodwill		0
Power supply agreements
Acquired Finite-Lived Intangible Assets [Line Items]
Preliminary fair value of intangible liabilities	$ 14,200,000
Power supply agreements | CLECO POWER
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible liabilities residual value	0
LTSA | Cleco Cajun
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible liabilities	$ 24,100,000
Intangible liabilities, remaining life	7 years
Right To Bill And Collect Storm Recovery Charges From Customers | Cleco Katrina/Rita
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired intangible asset			$ 177,500,000
Right to Bill and Collect, Storm Recovery Charges From Customers, Net of Financing Costs | Cleco Katrina/Rita
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired intangible asset			176,000,000.0
Financing costs | Cleco Katrina/Rita
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired intangible asset			$ 1,500,000
Trade name
Acquired Finite-Lived Intangible Assets [Line Items]
Residual value		$ 0
Intangible asset expected useful life (in years)		20 years
Power supply agreements
Acquired Finite-Lived Intangible Assets [Line Items]
Preliminary fair value of intangible assets	$ 98,900,000
Power supply agreements | MINIMUM
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible asset expected useful life (in years)		7 years
Power supply agreements | MAXIMUM
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible asset expected useful life (in years)		19 years
Power supply agreements | CLECO POWER
Acquired Finite-Lived Intangible Assets [Line Items]
Residual value	$ 0
Power supply agreements | CLECO POWER | MINIMUM
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets, remaining life (in years)	2 years
Power supply agreements | CLECO POWER | MAXIMUM
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets, remaining life (in years)	8 years