Pension Plan and Employee Benefits - Amounts Recognized in Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Non-current	$ 314,653	$ 283,075
OTHER BENEFITS
Defined Benefit Plan Disclosure [Line Items]
Current	4,463	4,401
Non-current	51,868	48,321
SERP BENEFITS
Defined Benefit Plan Disclosure [Line Items]
SERP, current	4,703	4,599
SERP, noncurrent	92,522	84,529
CLECO POWER
Defined Benefit Plan Disclosure [Line Items]
Non-current	230,825	206,270
CLECO POWER | OTHER BENEFITS
Defined Benefit Plan Disclosure [Line Items]
Current	3,865	3,815
Non-current	40,734	42,080
CLECO POWER | SERP BENEFITS
Defined Benefit Plan Disclosure [Line Items]
SERP, current	711	760
SERP, noncurrent	$ 19,828	$ 13,964