Fair Value Accounting, Carrying Value and Estimated Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Financial instruments not marked-to-market [Abstract]
Deferred debt issuance costs not included in the carrying value of long-term debt	$ 11,300	$ 11,600
Carrying Value
Financial instruments not marked-to-market [Abstract]
Long-term debt	2,905,222	2,866,955
FAIR VALUE
Financial instruments not marked-to-market [Abstract]
Long-term debt	2,924,772	2,921,325
Cleco Power
Financial instruments not marked-to-market [Abstract]
Deferred debt issuance costs not included in the carrying value of long-term debt	8,900	9,100
Cleco Power | Carrying Value
Financial instruments not marked-to-market [Abstract]
Long-term debt	1,410,188	1,369,810
Cleco Power | FAIR VALUE
Financial instruments not marked-to-market [Abstract]
Long-term debt	$ 1,555,341	$ 1,535,234