Fair Value Accounting, Commodity Contracts (Details) $ in Thousands, MWh in Millions	3 Months Ended
	Mar. 31, 2018 USD ($) MWh	Mar. 31, 2017 USD ($) MWh	Dec. 31, 2017 USD ($)
Price Risk Derivative | Derivatives Not Designated As Hedging Instrument
FTRs, at Fair Value, Net [Abstract]
Commodity-related contracts, net	$ 4,283		$ 7,044
FTRs [Abstract]
Net gain (loss) on FTRs recognized in income	12,483	$ 4,498
Price Risk Derivative | Derivatives Not Designated As Hedging Instrument | Energy risk management assets
FTRs, at Fair Value, Net [Abstract]
FTRs in energy risk management assets	4,828		7,396
Price Risk Derivative | Derivatives Not Designated As Hedging Instrument | Other current liabilities
FTRs, at Fair Value, Net [Abstract]
FTRs in Energy risk management liabilities	545		$ 352
Price Risk Derivative | Derivatives Not Designated As Hedging Instrument | Accumulated deferred fuel
FTRs [Abstract]
Unrealized gains (losses) associated with FTRs not recognized in income on derivatives	1,600	2,100
Price Risk Derivative | Derivatives Not Designated As Hedging Instrument | Electric operations
FTRs [Abstract]
Gain on FTRs recognized in income	18,150	9,163
Price Risk Derivative | Derivatives Not Designated As Hedging Instrument | Power purchased for utility customers
FTRs [Abstract]
Loss on FTRs recognized in income	$ (5,667)	$ (4,665)
Cleco Power
FTRs [Abstract]
Volume of FTRs Held (MWh) | MWh	3.8	9.0