Summary of Significant Accounting Policies, Goodwill (Details) - USD ($)	Aug. 01, 2017	Sep. 30, 2017	Dec. 31, 2016	Apr. 13, 2016
Goodwill [Line Items]
Goodwill recognized in connection with the completion of the Merger		$ 1,490,797,000	$ 1,490,797,000	$ 1,490,797,000
Carrying Value of Equity		$ 2,037,674,000	$ 2,046,763,000
Operating Segments [Member] | Cleco Power [Member]
Goodwill [Line Items]
Accumulated impairment loss on goodwill	$ 0
Fair Value of Equity	3,340,000,000
Carrying Value of Equity	$ 3,250,000,000
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount	3.00%
Reporting Unit, Amount of Fair Value in Excess of Carrying Amount	$ 89,500,000
Fair Value Inputs, Weighted-average cost of capital	5.20%
Fair Value Inputs, Long-term Cash Flow Growth Rate	2.50%
Operating Segments [Member] | Cleco Power [Member] | WACC, Lower Alternate [Member]
Goodwill [Line Items]
Fair Value of Equity	$ 3,430,000,000
Fair Value Inputs, Weighted-average cost of capital	5.10%
Operating Segments [Member] | Cleco Power [Member] | WACC, Higher Alternate [Member]
Goodwill [Line Items]
Fair Value of Equity	$ 3,250,000,000
Fair Value Inputs, Weighted-average cost of capital	5.30%
Operating Segments [Member] | Cleco Power [Member] | Long-term Cash Flow Growth Rate, Lower Alternate [Member]
Goodwill [Line Items]
Fair Value of Equity	$ 3,250,000,000
Fair Value Inputs, Long-term Cash Flow Growth Rate	2.40%
Operating Segments [Member] | Cleco Power [Member] | Long-term Cash Flow Growth Rate, Higher Alternate [Member]
Goodwill [Line Items]
Fair Value of Equity	$ 3,430,000,000
Fair Value Inputs, Long-term Cash Flow Growth Rate	2.60%