Litigation, Other Commitments and Contingencies, and Disclosures about Guarantees, New Markets Tax Credits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2008
New Markets Tax Credit [Line Items]
Liability component contained in the net asset	$ 0.8	$ 0.6
Tax benefits in excess of capital contributions	11.8
Cleco Holdings [Member]
New Markets Tax Credit [Line Items]
Membership interest in U.S Bank New Markets Tax Credit Fund (in hundredths)			99.90%
Equity contributions to be made to the Fund	285.5
Net tax benefits to be received from the Fund	303.8
Difference between equity contributions and total benefits received will be recognized over the life of the Fund as net tax benefits	$ 18.3
Period of Recognition of Gross Investment Amortization Expense (in years)	10 years