Fair Value Accounting - Carrying Value and Estimated Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred debt issuance costs not included in the carrying value of long-term debt	$ 13,500	$ 10,300
CARRYING VALUE
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	3,277,216	2,889,631
FAIR VALUE
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	3,327,937	2,859,924
CLECO POWER
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred debt issuance costs not included in the carrying value of long-term debt	8,100	8,300
CLECO POWER | CARRYING VALUE
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	1,390,627	1,400,930
CLECO POWER | FAIR VALUE
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 1,539,270	$ 1,517,152