Summary of Significant Accounting Policies - Restricted Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2020	Dec. 31, 2019
Restricted Cash and Cash Equivalents Items [Line Items]
Current	$ 4,619	$ 11,100
Non-current	744	15,203
Total restricted cash and cash equivalents	5,363	26,303
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	4,619	11,100
Non-current	0	14,363
Total restricted cash and cash equivalents	4,619	25,463
Cleco Katrina/Rita’s storm recovery bonds
Restricted Cash and Cash Equivalents Items [Line Items]
Current	2,626	9,632
Cleco Katrina/Rita’s storm recovery bonds \| CLECO POWER
Restricted Cash and Cash Equivalents Items [Line Items]
Current	2,626	9,632
Charitable contributions
Restricted Cash and Cash Equivalents Items [Line Items]
Current	1,765	1,200
Non-current	0	2,094
Charitable contributions \| CLECO POWER
Restricted Cash and Cash Equivalents Items [Line Items]
Current	1,765	1,200
Non-current	0	2,094
Rate credit escrow
Restricted Cash and Cash Equivalents Items [Line Items]
Current	228	268
Rate credit escrow \| CLECO POWER
Restricted Cash and Cash Equivalents Items [Line Items]
Current	228	268
Diversified Lands’ mitigation escrow
Restricted Cash and Cash Equivalents Items [Line Items]
Non-current	23	21
Cleco Cajun’s defense fund
Restricted Cash and Cash Equivalents Items [Line Items]
Non-current	721	719
Cleco Cajun’s margin deposits
Restricted Cash and Cash Equivalents Items [Line Items]
Non-current	0	100
Future storm restoration costs
Restricted Cash and Cash Equivalents Items [Line Items]
Non-current	0	12,269
Decrease in restricted cash and cash equivalents	12,300
Future storm restoration costs \| Hurricane Laura
Restricted Cash and Cash Equivalents Items [Line Items]
Decrease in restricted cash and cash equivalents	8,300
Future storm restoration costs \| Other Storms
Restricted Cash and Cash Equivalents Items [Line Items]
Decrease in restricted cash and cash equivalents	4,000
Future storm restoration costs \| CLECO POWER
Restricted Cash and Cash Equivalents Items [Line Items]
Non-current	0	$ 12,269
Cleco Katrina/Rita scheduled storm recovery bond principal payments
Restricted Cash and Cash Equivalents Items [Line Items]
Payments for investment in restricted cash from pollution control bond	11,100
Cleco Katrina/Rita related interest payments
Restricted Cash and Cash Equivalents Items [Line Items]
Payments for investment in restricted cash from pollution control bond	300
Cleco Katrina/Rita administration fees
Restricted Cash and Cash Equivalents Items [Line Items]
Payments from distribution in restricted cash from pollution control bond	$ 4,400

Restricted Cash Remaining From Pollution Control Bond

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The cash outflow for investments in restricted cash from pollution control bond, which is a debt security issued by a state, certain agencies or authorities, a local government, or development corporation to finance the construction of air- or water-pollution control facilities or sewage or solid waste disposal facilities pursuant to federal law. The bonds are backed by the credit of the beneficiary of the financing rather than the credit of the issuer.

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