Income Taxes, Narrative (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Uncertain Tax Positions [Line Items]
Interest payable related to uncertain tax positions	$ 0		$ 0
Interest expense related to uncertain tax positions	0	$ 0
Liability for uncertain tax positions	0
Penalties	0	0
Decrease in deferred income taxes			46,300,000
Decrease in accumulated deferred income tax liability	0		394,900,000
Cleco Power
Uncertain Tax Positions [Line Items]
Interest payable related to uncertain tax positions	0		0
Interest expense related to uncertain tax positions	0	$ 0
Decrease in deferred income taxes			14,300,000
Decrease in accumulated deferred income tax liability	$ 0		$ 362,900,000