Fair Value Accounting and Financial Instruments - Fair Value of Derivative Instruments as Recorded in Condensed Consolidated Balance Sheets (Details) - DERIVATIVES NOT DESIGNATED AS HEDGING INSTRUMENTS - USD ($)	Sep. 30, 2021	Dec. 31, 2020
GROSS ASSET (LIABILITY)
Commodity-related contracts, net	$ 149,541,000
GROSS AMOUNTS OFFSET ON THE BALANCE SHEET
Derivative, contract netting	0
Derivative, collateral total	(8,900,000)
NET ASSET (LIABILITY) ON THE BALANCE SHEET
Net asset (liability) on the balance sheet	140,641,000	$ 10,167,000
GROSS AMOUNTS NOT OFFSET ON THE BALANCE SHEET (1)
Collateral, assets	(55,000,000)
NET AMOUNT
Net amount	85,641,000
Price risk derivatives | CLECO POWER
GROSS ASSET (LIABILITY)
Commodity-related contracts, net	4,698,000	3,216,000
Price risk derivatives | Energy risk management assets, current
GROSS ASSET (LIABILITY)
Derivative asset	9,338,000
GROSS AMOUNTS OFFSET ON THE BALANCE SHEET
Derivative asset, contract netting	0
Derivative asset, collateral	0
NET ASSET (LIABILITY) ON THE BALANCE SHEET
Derivative asset	9,338,000	4,805,000
GROSS AMOUNTS NOT OFFSET ON THE BALANCE SHEET (1)
Collateral, assets	0
NET AMOUNT
Derivative asset, net	9,338,000
Price risk derivatives | Energy risk management assets, current | CLECO POWER
GROSS ASSET (LIABILITY)
Derivative asset	6,028,000	4,337,000
Price risk derivatives | Energy risk management liabilities
GROSS ASSET (LIABILITY)
Derivative liability	(1,589,000)
GROSS AMOUNTS OFFSET ON THE BALANCE SHEET
Derivative liability, contract netting	0
Derivative liability, collateral	0
NET ASSET (LIABILITY) ON THE BALANCE SHEET
Derivative liability	(1,589,000)	(1,625,000)
GROSS AMOUNTS NOT OFFSET ON THE BALANCE SHEET (1)
Collateral, liability	0
NET AMOUNT
Derivative liability, net	(1,589,000)
Price risk derivatives | Energy risk management liabilities | CLECO POWER
GROSS ASSET (LIABILITY)
Derivative liability	(1,330,000)	(1,121,000)
Natural gas derivatives* | Energy risk management assets, current
GROSS ASSET (LIABILITY)
Derivative asset	59,648,000
GROSS AMOUNTS OFFSET ON THE BALANCE SHEET
Derivative asset, contract netting	(1,283,000)
Derivative asset, collateral	(8,900,000)	0
NET ASSET (LIABILITY) ON THE BALANCE SHEET
Derivative asset	49,465,000	8,276,000
GROSS AMOUNTS NOT OFFSET ON THE BALANCE SHEET (1)
Collateral, assets	(41,098,000)
NET AMOUNT
Derivative asset, net	8,367,000
Natural gas derivatives* | Energy risk management liabilities
GROSS ASSET (LIABILITY)
Derivative liability	(1,283,000)
GROSS AMOUNTS OFFSET ON THE BALANCE SHEET
Derivative liability, contract netting	1,283,000
Derivative liability, collateral	0
NET ASSET (LIABILITY) ON THE BALANCE SHEET
Derivative liability	0	(828,000)
GROSS AMOUNTS NOT OFFSET ON THE BALANCE SHEET (1)
Collateral, liability	0
NET AMOUNT
Derivative liability, net	0
Natural gas derivatives* | Energy risk management assets, noncurrent
GROSS ASSET (LIABILITY)
Derivative asset	83,427,000
GROSS AMOUNTS OFFSET ON THE BALANCE SHEET
Derivative asset, contract netting	0
Derivative asset, collateral	0
NET ASSET (LIABILITY) ON THE BALANCE SHEET
Derivative asset	83,427,000	323,000
GROSS AMOUNTS NOT OFFSET ON THE BALANCE SHEET (1)
Collateral, assets	(13,902,000)
NET AMOUNT
Derivative asset, net	69,525,000
Natural gas derivatives* | Other deferred credits
GROSS ASSET (LIABILITY)
Derivative liability	0
GROSS AMOUNTS OFFSET ON THE BALANCE SHEET
Derivative liability, contract netting	0
Derivative liability, collateral	0
NET ASSET (LIABILITY) ON THE BALANCE SHEET
Derivative liability	0	$ (784,000)
GROSS AMOUNTS NOT OFFSET ON THE BALANCE SHEET (1)
Collateral, liability	0
NET AMOUNT
Derivative liability, net	$ 0