Pension Plan and Employee Benefits - Current and Non-Current Portions of SERP Liability (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Non-current	$ 285,964	$ 283,075
SERP Benefits
Defined Benefit Plan Disclosure [Line Items]
Current	4,599	4,599
Non-current	83,619	84,529
CLECO POWER
Defined Benefit Plan Disclosure [Line Items]
Non-current	209,809	206,270
CLECO POWER | SERP Benefits
Defined Benefit Plan Disclosure [Line Items]
Current	760	760
Non-current	$ 13,665	$ 13,964