Fair Value Accounting - Amount of Gain (Loss) Recognized in Income on Derivatives (Details) - DERIVATIVES NOT DESIGNATED AS HEDGING INSTRUMENTS - Commodity-related contracts - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Commodity-related contracts
Net gain (loss) recognized in income on derivatives	$ (49,218)	$ 11,260	$ (56,548)	$ 5,167
Accumulated deferred fuel
Commodity-related contracts
Unrealized gains (losses) associated with FTRs	(400)	(1,300)	(400)	(1,300)
CLECO POWER
Commodity-related contracts
Net gain (loss) recognized in income on derivatives	530	533	794	1,179
CLECO POWER | Accumulated deferred fuel
Commodity-related contracts
Unrealized gains (losses) associated with FTRs	(400)	(1,300)	(400)	(1,300)
Electric operations
Commodity-related contracts
Net gain (loss) recognized in income on derivatives	1,763	1,852	9,207	3,248
Electric operations | CLECO POWER
Commodity-related contracts
Net gain (loss) recognized in income on derivatives	1,763	1,852	9,208	3,249
Purchased power
Commodity-related contracts
Net gain (loss) recognized in income on derivatives	702	92	(7,858)	(289)
Purchased power | CLECO POWER
Commodity-related contracts
Net gain (loss) recognized in income on derivatives	(1,233)	(1,319)	(8,414)	(2,070)
Fuel used for electric generation
Commodity-related contracts
Net gain (loss) recognized in income on derivatives	$ (51,683)	$ 9,316	$ (57,897)	$ 2,208