Fair Value Accounting - Institutional Money Market Funds (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Cash equivalents	$ 80,712	$ 103,409
Cleco Power
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Cash equivalents	20,812	49,509
Restricted Cash and Cash Equivalents, Current
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Restricted cash and cash equivalents	4,545	11,100
Restricted Cash and Cash Equivalents, Current | Cleco Power
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Restricted cash and cash equivalents	4,545	11,100
Restricted Cash and Cash Equivalents, Noncurrent
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Restricted cash and cash equivalents	744	15,134
Restricted Cash and Cash Equivalents, Noncurrent | Cleco Power
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Restricted cash and cash equivalents	$ 0	$ 14,294