Fair Value Accounting - Fair Value of Derivative Instruments as Recorded in Condensed Consolidated Balance Sheets (Details) - Derivatives Not Designated as Hedging Instrument - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Commodity-related contracts
Commodity-related contracts, net	$ 10,167	$ 606
CLECO POWER
Commodity-related contracts
Commodity-related contracts, net	3,216	5,725
FTRs | Energy risk management assets
Commodity-related contracts
Derivative asset	4,805	6,822
FTRs | Energy risk management assets | CLECO POWER
Commodity-related contracts
Derivative asset	4,337	6,311
FTRs | Energy risk management liabilities
Commodity-related contracts
Derivative liability	(1,625)	(1,044)
FTRs | Energy risk management liabilities | CLECO POWER
Commodity-related contracts
Derivative liability	(1,121)	(586)
Other commodity derivatives | Energy risk management assets
Commodity-related contracts
Derivative asset	8,276	201
Other commodity derivatives | Energy risk management liabilities
Commodity-related contracts
Derivative liability	(828)	(3,069)
Other commodity derivatives | Other deferred charges
Commodity-related contracts
Derivative asset	323	0
Other commodity derivatives | Other deferred credits
Commodity-related contracts
Derivative liability	$ (784)	$ (2,304)