Intangible Assets and Goodwill (Details) - USD ($)			9 Months Ended	12 Months Ended
	Aug. 01, 2017	Apr. 13, 2016	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2008
Acquired Finite-Lived Intangible Assets [Line Items]
Members' Equity			$ 2,046,763,000	$ 2,096,357,000	$ 2,046,763,000
Goodwill, Impairment Loss				0	0
Intangible asset, net [Abstract]
Cleco Katrina/Rita right to bill and collect storm recovery charges			70,594,000	70,594,000	70,594,000
Power supply agreements			86,726,000	85,104,000	86,726,000
Trade name			5,100,000	5,100,000	5,100,000
Gross carrying amount			162,420,000	160,798,000	162,420,000
Accumulated amortization			(19,786,000)	(45,948,000)	(19,786,000)
Net intangible assets subject to amortization			142,634,000	114,850,000	142,634,000
Expected amortization expense [Abstract]
2018				29,247,000
2019				32,324,000
2020				9,935,000
2021				9,935,000
2022				9,935,000
Thereafter				23,474,000
Goodwill		$ 1,490,797,000	1,490,797,000	1,490,797,000	1,490,797,000
Equity Method Investment, Other than Temporary Impairment				0	0
Successor [Member]
Expected amortization expense [Abstract]
Goodwill			1,490,797,000	1,490,797,000	1,490,797,000
Transmission Service Agreement [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Residual value of intangible asset		$ 0
Transmission Service Agreement [Member] | Successor [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization expense			$ 7,500,000	10,800,000
Trade Names [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible asset expected useful life (in years)		20 years	20 years
Residual value of intangible asset		$ 0
Trade Names [Member] | Successor [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization expense			$ 200,000	300,000
Minimum [Member] | Transmission Service Agreement [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible asset expected useful life (in years)		5 years
Maximum [Member] | Transmission Service Agreement [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible asset expected useful life (in years)		17 years
Other Subsidiaries [Member] | Right to bill and collect storm recovery charges from customers [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired intangible asset							$ 177,500,000
Residual value of intangible asset							0
Amortization expense				16,800,000	16,500,000	$ 15,700,000
Intangible asset, net [Abstract]
Accumulated amortization		$ 0
Other Subsidiaries [Member] | Contractual Rights [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired intangible asset							176,000,000
Other Subsidiaries [Member] | Financing costs [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired intangible asset							$ 1,500,000
Other Subsidiaries [Member] | Minimum [Member] | Right to bill and collect storm recovery charges from customers [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible asset expected useful life (in years)							12 years
Other Subsidiaries [Member] | Maximum [Member] | Right to bill and collect storm recovery charges from customers [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible asset expected useful life (in years)							15 years
Cleco Power [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Members' Equity			1,535,202,000	1,550,679,000	1,535,202,000
Intangible asset, net [Abstract]
Cleco Katrina/Rita right to bill and collect storm recovery charges			177,537,000	177,537,000	177,537,000
Accumulated amortization			(119,064,000)	(135,836,000)	(119,064,000)
Net intangible assets subject to amortization			$ 58,473,000	41,701,000	$ 58,473,000
Expected amortization expense [Abstract]
2018				19,312,000
2019				$ 22,389,000
Cleco Power [Member] | Operating Segments [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill, Impaired, Accumulated Impairment Loss	$ 0
Fair Value Inputs, Weighted-average Cost of Capital	5.20%
Equity, Fair Value Disclosure	$ 3,340,000,000
Fair Value Inputs, Long-term Cash Flow Growth Rate	2.50%
Members' Equity	$ 3,250,000,000
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount	3.00%
Reporting Unit, Amount of Fair Value in Excess of Carrying Amount	$ 89,500,000
WACC, Lower Alternate [Member] | Cleco Power [Member] | Operating Segments [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair Value Inputs, Weighted-average Cost of Capital	5.10%
Equity, Fair Value Disclosure	$ 3,430,000,000
WACC, Higher Alternate [Member] | Cleco Power [Member] | Operating Segments [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair Value Inputs, Weighted-average Cost of Capital	5.30%
Equity, Fair Value Disclosure	$ 3,250,000,000
Long-term Cash Flow Growth Rate, Lower Alternate [Member] | Cleco Power [Member] | Operating Segments [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Equity, Fair Value Disclosure	$ 3,250,000,000
Fair Value Inputs, Long-term Cash Flow Growth Rate	2.40%
Long-term Cash Flow Growth Rate, Higher Alternate [Member] | Cleco Power [Member] | Operating Segments [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Equity, Fair Value Disclosure	$ 3,430,000,000
Fair Value Inputs, Long-term Cash Flow Growth Rate	2.60%