Fair Value Accounting - Carrying Value and Estimated Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 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	$ 14,200	$ 10,300
CARRYING VALUE
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	3,191,452	2,889,631
FAIR VALUE
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	3,407,190	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	7,600	8,300
CLECO POWER | CARRYING VALUE
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	1,380,605	1,400,930
CLECO POWER | FAIR VALUE
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 1,625,480	$ 1,517,152