Pension Plan and Employee Benefits - Narrative (Details)			12 Months Ended
	Sep. 12, 2019 USD ($)	Mar. 30, 2017 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($) bonus	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) executive_officer	Mar. 29, 2017
PENSION BENEFITS
Defined Benefit Plan Disclosure [Line Items]
Consecutive calendar years				5 years
Most recent period of employment				10 years
Employer contributions	$ 12,300,000			$ 12,250,000	$ 0
Estimated pension contributions required through 2024				61,800,000
Net periodic benefit cost				$ 12,175,000	$ 18,835,000	$ 16,560,000
Expected return on plan assets				6.55%	5.86%	6.08%
Actual return on plan assets				22.17%	(7.31%)
Discount rate				3.43%	4.35%
OTHER BENEFITS
Defined Benefit Plan Disclosure [Line Items]
Employer contributions				$ 0	$ 0
Net periodic benefit cost				2,858,000	$ 2,920,000	$ 2,965,000
Assets set aside in a trust				$ 0
Assumed health care cost trend rates for next fiscal year				5.00%	5.00%
Ultimate health care trend rate				5.00%
Discount rate				3.25%	4.16%
SERP BENEFITS
Defined Benefit Plan Disclosure [Line Items]
Consecutive calendar years				5 years
Most recent period of employment				60 months
Net periodic benefit cost				$ 5,040,000	$ 6,372,000	$ 5,963,000
Number of highest cash bonuses | bonus				5
Number of executive officers with capped benefits | executive_officer						2
Discount rate		4.08%		3.37%	4.34%		4.22%
Special/contractual termination benefits		$ (300,000)		$ 0	$ 0	$ (315,000)
CLECO POWER | PENSION BENEFITS
Defined Benefit Plan Disclosure [Line Items]
Employer contributions				83,000,000
CLECO POWER | OTHER BENEFITS
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost				3,100,000	3,300,000	3,300,000
CLECO POWER | SERP BENEFITS
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost				800,000	1,400,000	1,300,000
Support Group | PENSION BENEFITS
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost				$ 2,200,000	$ 2,000,000	$ 1,800,000
Forecast [Member] | PENSION BENEFITS
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets			5.91%
Increase in expected pension costs			$ 6,000,000