Fair Value Accounting, Carrying Value and Estimated Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financial instruments not marked-to-market [Abstract]
Deferred debt issuance costs not included in the carrying value of long-term debt	$ 11,600	$ 11,700
Estimated Fair Value [Member]
Financial instruments not marked-to-market [Abstract]
Long-term debt	2,921,325	2,754,518
Carrying Value [Member]
Financial instruments not marked-to-market [Abstract]
Long-term debt	2,866,955	2,768,149
Cleco Power [Member]
Financial instruments not marked-to-market [Abstract]
Deferred debt issuance costs not included in the carrying value of long-term debt	9,141	9,421
Cleco Power [Member] | Estimated Fair Value [Member]
Financial instruments not marked-to-market [Abstract]
Long-term debt	1,535,234	1,418,693
Cleco Power [Member] | Carrying Value [Member]
Financial instruments not marked-to-market [Abstract]
Long-term debt	$ 1,369,810	$ 1,262,373