Summary of Significant Accounting Policies - Property, Plant, and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Feb. 04, 2019
Public Utility, Property, Plant and Equipment [Line Items]
Capitalized software, net	$ 178,100	$ 168,600
Capitalized software costs, amortization	11,015	4,917	$ 2,154
Property, plant and equipment, net	4,789,541	4,645,011
Utility plants
Generation	2,915,349	2,812,843
Distribution	1,357,714	1,153,086
Transmission	667,398	660,279
Other utility plant	391,057	350,683
Other property, plant, and equipment	5,672	5,364
Total property, plant, and equipment	5,337,190	4,982,255
Accumulated depreciation	(672,271)	(454,874)
Net property, plant, and equipment	$ 4,664,919	4,527,381
MINIMUM
Estimated Useful Lives (in years)
Utility plants, generation (in years)	6 years
Utility plants, distribution (in years)	15 years
Utility plants, transmission (in years)	5 years
Utility plants, other utility plant (in years)	2 years
Other property, plant, and equipment (in years)	5 years
MAXIMUM
Estimated Useful Lives (in years)
Utility plants, generation (in years)	95 years
Utility plants, distribution (in years)	50 years
Utility plants, transmission (in years)	55 years
Utility plants, other utility plant (in years)	45 years
Other property, plant, and equipment (in years)	45 years
CLECO POWER
Public Utility, Property, Plant and Equipment [Line Items]
Capitalized software, net	$ 177,000	166,200
Capitalized software costs, amortization	10,379	4,321	$ 1,607
Property, plant and equipment, net	3,867,629	3,696,113
Utility plants
Generation	2,673,271	2,633,590
Distribution	1,796,841	1,593,104
Transmission	857,833	805,701
Other utility plant	496,433	457,062
Total property, plant, and equipment	5,824,378	5,489,457
Accumulated depreciation	(2,067,362)	(1,905,031)
Net property, plant, and equipment	$ 3,757,016	$ 3,584,426
CLECO POWER | MINIMUM
Estimated Useful Lives (in years)
Utility plants, generation (in years)	10 years
Utility plants, distribution (in years)	15 years
Utility plants, transmission (in years)	5 years
Utility plants, other utility plant (in years)	5 years
Other property, plant, and equipment (in years)	5 years
CLECO POWER | MAXIMUM
Estimated Useful Lives (in years)
Utility plants, generation (in years)	95 years
Utility plants, distribution (in years)	50 years
Utility plants, transmission (in years)	55 years
Utility plants, other utility plant (in years)	45 years
Other property, plant, and equipment (in years)	45 years
Cleco Cajun
Public Utility, Property, Plant and Equipment [Line Items]
Property, plant and equipment, net				$ 741,200