Litigation, Other Commitments and Contingencies, and Disclosures about Guarantees, Off-Balance Sheet Commitments and Guarantees (Details) $ in Millions	Dec. 31, 2017 USD ($)
Performance Guarantee [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	$ 42.4
Indemnification Agreement [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	40.0
Indemnification Agreement, Including Fundamental Organizational Structure [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	400.0
Cleco Power [Member] | Indemnification Agreement [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	40.0
Cleco Power [Member] | Indemnification Agreement, Including Fundamental Organizational Structure [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	400.0
Cleco Power [Member] | Guarantee Issued to Entergy Mississippi on behalf of Attala [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	$ 106.5