Litigation, Other Commitments and Contingencies, and Disclosures about Guarantees - Litigation (Details) $ in Millions				1 Months Ended						3 Months Ended	9 Months Ended	24 Months Ended	30 Months Ended
	May 21, 2020	Mar. 03, 2020 USD ($)	Jan. 01, 2020	Mar. 31, 2018 plaintiff	Sep. 30, 2016	Jun. 30, 2016	Sep. 30, 2015 USD ($)	Dec. 31, 2014 claim	Nov. 30, 2014	Mar. 31, 2017 claim generation_unit	Sep. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	May 31, 2016 complaint	Sep. 27, 2019 recommendation finding	Feb. 04, 2019 USD ($)
Loss Contingencies [Line Items]
Loss contingency, estimate of possible loss											$ 5.3
South Central Generating
Loss Contingencies [Line Items]
Indemnification asset															$ 10.0
Contingent liability															$ 10.0
FERC
Loss Contingencies [Line Items]
Estimated refund interest amount											2.7
FERC | MISO Transmission Rates
Loss Contingencies [Line Items]
Public utilities, requested rate increase (decrease), percentage (in hundredths)									0.50%
Gulf Coast Spinning start up costs
Loss Contingencies [Line Items]
Allegations by plaintiff, failure to perform							$ 6.5
Gulf Coast Spinning construction of cotton spinning facility
Loss Contingencies [Line Items]
Allegations by plaintiff, failure to perform							$ 60.0
Actions filed in the 9th Judicial District Court | Alleged Breach of Fiduciary Duties
Loss Contingencies [Line Items]
Number of actions filed | claim										4
Actions filed in the Civil District Court | Alleged Breach of Fiduciary Duties
Loss Contingencies [Line Items]
Number of actions filed | claim								3		3
Larry Addison, Et Al. V. Sabine River Authority of Texas, Et Al | Pending Litigation
Loss Contingencies [Line Items]
Number of plaintiffs | plaintiff				26
Perry Bonin, Ace Chandler, and Michael Manuel, et al v. Sabine River Authority of Texas and Sabine River Authority of Louisiana, No. B-160173-C | Pending Litigation
Loss Contingencies [Line Items]
Number of generation units failed to repair | generation_unit										1
Number of generation units owned | generation_unit										2
CLECO POWER | LPSC 2018-2019 Fuel Audit
Loss Contingencies [Line Items]
Fuel expense												$ 565.8
CLECO POWER | MISO Transmission Rates
Loss Contingencies [Line Items]
Public utilities, proposed return on equity, percentage (in hundredths)			10.38%		10.32%	9.70%
CLECO POWER | LPSC
Loss Contingencies [Line Items]
Environmental expense		$ 26.2
CLECO POWER | FERC
Loss Contingencies [Line Items]
Number of findings | finding														12
Number of recommendations | recommendation														59
Estimated refund interest amount											2.7
Loss contingency, estimate of possible loss											$ 0.6
CLECO POWER | FERC | MISO Transmission Rates
Loss Contingencies [Line Items]
Number of actions filed | complaint													2
Public utilities, approved return on equity, percentage (In hundredths)													12.38%
Public utilities, proposed return on equity, percentage (in hundredths)	10.02%				9.88%								6.68%