Pension Plan and Employee Benefits - Benefit Obligation, Plan Assets, and Funded Status (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
PENSION BENEFITS
Change in benefit obligation
Benefit obligation at beginning of period	$ 525,482	$ 500,869
Service cost	4,619	4,977	$ 8,589
Interest cost	26,140	26,423	19,841
Actuarial loss (gain)	(25,647)	26,300
Expenses paid	(3,396)	(3,018)
Transfer to Cleco Cajun Purchasers	(1,674)	0
Derecognition of Cleco Cajun liability	0	0
Benefits paid	(30,660)	(30,069)
Benefit obligation at end of period	494,864	525,482	500,869
Change in plan assets
Fair value of plan assets at beginning of period	408,159	402,285
Actual (loss) gain return on plan assets	11,091	38,761
Employer contributions	25,750	200
Expenses paid	(3,396)	(3,018)
Transfer to Cleco Cajun Purchasers	(1,674)	0
Benefits paid	(30,660)	(30,069)
Fair value of plan assets at end of period	409,270	408,159	402,285
Unfunded status	(85,594)	(117,323)
Accumulated benefit obligation	479,948	505,508
OTHER BENEFITS
Change in benefit obligation
Benefit obligation at beginning of period	47,056	43,306
Service cost	1,907	1,472	2,204
Interest cost	2,322	2,285	1,484
Actuarial loss (gain)	(2,011)	(5,110)
Expenses paid	0	0
Transfer to Cleco Cajun Purchasers	0	0
Derecognition of Cleco Cajun liability	(380)	0
Benefits paid	(4,891)	(5,117)
Benefit obligation at end of period	44,003	47,056	43,306
Change in plan assets
Fair value of plan assets at beginning of period	0	0
Actual (loss) gain return on plan assets	0	0
Employer contributions	0	0
Expenses paid	0	0
Transfer to Cleco Cajun Purchasers	0	0
Benefits paid	0	0
Fair value of plan assets at end of period	0	0	0
Unfunded status	(44,003)	(47,056)
SERP BENEFITS
Change in benefit obligation
Benefit obligation at beginning of period	67,462	68,427
Service cost	134	142	227
Interest cost	3,343	3,604	2,679
Actuarial loss (gain)	(2,814)	(345)
Benefits paid	(4,582)	(4,366)
Benefit obligation at end of period	63,543	67,462	$ 68,427
Change in plan assets
Accumulated benefit obligation	$ 63,543	$ 67,462