Intangible Assets, Intangible Liabilities, and Goodwill - Intangible Assets Subject to Amortization (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 259,698	$ 259,698
Intangible liabilities, gross	38,300	38,300
Net intangible assets carrying amount	221,398	221,398
Accumulated amortization	(134,526)	(115,167)
Net intangible assets subject to amortization	86,872	106,231
LTSA
Finite-Lived Intangible Assets [Line Items]
Intangible liabilities, gross	24,100	24,100
Power supply agreements
Finite-Lived Intangible Assets [Line Items]
Intangible liabilities, gross	14,200	14,200
Cleco Katrina/Rita right to bill and collect storm recover charges
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	70,594	70,594
Cleco Katrina/Rita right to bill and collect storm recover charges | CLECO POWER
Finite-Lived Intangible Assets [Line Items]
Net intangible assets carrying amount	177,537	177,537
Accumulated amortization	(177,537)	(177,020)
Net intangible assets subject to amortization	0	517
Trade name
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	5,100	5,100
Power supply agreements
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 184,004	$ 184,004