Summary of Significant Accounting Policies - Restricted Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Restricted Cash and Cash Equivalents Items [Line Items]
Current	$ 4,430	$ 4,545
Non-current	744	744
Total restricted cash and cash equivalents	5,174	5,289
Remaining restricted cash to be used for final administration and winding up activities	2,600
CLECO POWER
Restricted Cash and Cash Equivalents Items [Line Items]
Current	4,430	4,545
Total restricted cash and cash equivalents	4,430	4,545
Cleco Katrina/Rita’s storm recovery bonds
Restricted Cash and Cash Equivalents Items [Line Items]
Current	2,626	2,626
Cleco Katrina/Rita’s storm recovery bonds | CLECO POWER
Restricted Cash and Cash Equivalents Items [Line Items]
Current	2,626	2,626
Charitable contributions
Restricted Cash and Cash Equivalents Items [Line Items]
Current	1,603	1,718
Charitable contributions | CLECO POWER
Restricted Cash and Cash Equivalents Items [Line Items]
Current	1,603	1,718
Rate credit escrow
Restricted Cash and Cash Equivalents Items [Line Items]
Current	201	201
Rate credit escrow | CLECO POWER
Restricted Cash and Cash Equivalents Items [Line Items]
Current	201	201
Diversified Lands’ mitigation escrow
Restricted Cash and Cash Equivalents Items [Line Items]
Non-current	22	22
Cleco Cajun’s defense fund
Restricted Cash and Cash Equivalents Items [Line Items]
Non-current	$ 722	$ 722