Pension Plan and Employee Benefits - Components of Periodic Benefit Costs and Weighted-Average Assumptions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
PENSION BENEFITS
Components of periodic benefit costs
Service cost	$ 4,619	$ 4,977	$ 8,589
Interest cost	26,140	26,423	19,841
Expected return on plan assets	(30,428)	(29,544)	(24,706)
Amortizations
Net loss (gain)	0	0	12,332
Gain on derecognition of Cleco Cajun	0	0	0
Net periodic benefit cost	$ 331	$ 1,856	$ 16,056
Weighted-average assumptions used to determine the benefit obligation
Discount rate	5.66%	5.13%
Rate of compensation increase	3.00%	3.50%
Weighted-average assumptions used to determine the net benefit cost
Discount rate	5.13%	5.44%	2.98%
Expected return on plan assets	6.68%	6.60%	5.25%
Rate of compensation increase	3.50%	2.76%	2.73%
OTHER BENEFITS
Components of periodic benefit costs
Service cost	$ 1,907	$ 1,472	$ 2,204
Interest cost	2,322	2,285	1,484
Expected return on plan assets	0	0	0
Amortizations
Net loss (gain)	646	(45)	1,210
Gain on derecognition of Cleco Cajun	(169)	0	0
Net periodic benefit cost	$ 4,706	$ 3,712	$ 4,898
Weighted-average assumptions used to determine the benefit obligation
Discount rate	5.61%	5.25%
Weighted-average assumptions used to determine the net benefit cost
Discount rate	5.25%	5.61%	2.82%
SERP BENEFITS
Components of periodic benefit costs
Service cost	$ 134	$ 142	$ 227
Interest cost	3,343	3,604	2,679
Amortizations
Prior service credit	(215)	(215)	(215)
Net loss (gain)	(81)	(63)	1,049
Net periodic benefit cost	$ 3,181	$ 3,468	$ 3,740
Weighted-average assumptions used to determine the benefit obligation
Discount rate	5.65%	5.13%
Weighted-average assumptions used to determine the net benefit cost
Discount rate	5.13%	5.46%	2.95%