Fair Value Accounting - Fair Value of Derivative Instruments as Recorded in Condensed Consolidated Balance Sheets (Details) - DERIVATIVES NOT DESIGNATED AS HEDGING INSTRUMENTS - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Commodity-related contracts
Commodity-related contracts, net	$ 12,720	$ 10,167
Commodity-related contracts | CLECO POWER
Commodity-related contracts
Commodity-related contracts, net	1,088	3,216
Commodity-related contracts | Energy risk management assets
Commodity-related contracts
Derivative asset	2,140	4,805
Commodity-related contracts | Energy risk management assets | CLECO POWER
Commodity-related contracts
Derivative asset	1,986	4,337
Commodity-related contracts | Energy risk management liabilities
Commodity-related contracts
Derivative liability	(1,117)	(1,625)
Commodity-related contracts | Energy risk management liabilities | CLECO POWER
Commodity-related contracts
Derivative liability	(898)	(1,121)
Other commodity derivatives | Energy risk management assets
Commodity-related contracts
Derivative asset	9,159	8,276
Other commodity derivatives | Energy risk management liabilities
Commodity-related contracts
Derivative liability	(325)	(828)
Other commodity derivatives | Other deferred charges
Commodity-related contracts
Derivative asset	2,966	323
Other commodity derivatives | Other deferred credits
Commodity-related contracts
Derivative liability	$ (103)	$ (784)