Regulation and Rates - Provision for Rate Refund (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Jul. 31, 2019
Regulation and Rates [Line Items]
Provision for rate refund	$ 5,465	$ 9,444
Cleco Katrina/Rita storm recovery charges
Regulation and Rates [Line Items]
Provision for rate refund	1,610	1,617
FERC audit
Regulation and Rates [Line Items]
Provision for rate refund	0	1,912
FRP
Regulation and Rates [Line Items]
Provision for rate refund	1,236	1,786
Site-specific industrial customer
Regulation and Rates [Line Items]
Provision for rate refund	611	710
TCJA
Regulation and Rates [Line Items]
Provision for rate refund	2,057	2,057
Transmission ROE
Regulation and Rates [Line Items]
Provision for rate refund	0	595
CLECO POWER
Regulation and Rates [Line Items]
Provision for rate refund	5,465	8,630		$ 79,200
CLECO POWER | Cleco Katrina/Rita storm recovery charges
Regulation and Rates [Line Items]
Provision for rate refund	1,610	1,617
CLECO POWER | FERC audit
Regulation and Rates [Line Items]
Provision for rate refund	0	1,912
CLECO POWER | FRP
Regulation and Rates [Line Items]
Provision for rate refund	1,236	1,786	$ 1,200
CLECO POWER | Site-specific industrial customer
Regulation and Rates [Line Items]
Provision for rate refund	611	710
CLECO POWER | TCJA
Regulation and Rates [Line Items]
Provision for rate refund	2,057	2,057
CLECO POWER | Transmission ROE
Regulation and Rates [Line Items]
Provision for rate refund	$ 0	$ 595