Summary of Significant Accounting Policies - Property, Plant, and Equipment (Details) - USD ($)	3 Months Ended	9 Months Ended	12 Months Ended
	Apr. 12, 2016	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Apr. 13, 2016
Public Utility, Property, Plant and Equipment [Line Items]
Accumulated depreciation			$ 303,727,000	$ 192,348,000		$ 0
Capitalized software, net			7,200,000	7,900,000
Utility plants
Generation			1,949,042,000	1,908,344,000
Distribution			1,081,650,000	1,015,472,000
Transmission			519,269,000	512,428,000
Other utility plant			174,010,000	153,900,000
Other property, plant, and equipment			4,506,000	4,381,000
Total property, plant, and equipment			3,728,477,000	3,594,525,000
Accumulated depreciation			(303,727,000)	(192,348,000)		$ 0
Net property, plant, and equipment			3,424,750,000	3,402,177,000
SUCCESSOR
Public Utility, Property, Plant and Equipment [Line Items]
Capitalized software costs, amortization		$ 2,351,000	$ 2,154,000	2,367,000
PREDECESSOR
Public Utility, Property, Plant and Equipment [Line Items]
Capitalized software costs, amortization	$ 921,000
MINIMUM
Estimated Useful Lives (in years)
Utility Plants, Generation			10 years
Utility Plants, Distribution			15 years
Utility Plants, Transmission			5 years
Utility Plants, Other utility plant			5 years
Other property, plant, and equipment (in years)			5 years
MAXIMUM
Estimated Useful Lives (in years)
Utility Plants, Generation			95 years
Utility Plants, Distribution			50 years
Utility Plants, Transmission			55 years
Utility Plants, Other utility plant			45 years
Other property, plant, and equipment (in years)			45 years
CLECO POWER
Public Utility, Property, Plant and Equipment [Line Items]
Accumulated depreciation			$ 1,804,563,000	1,712,590,000
Capitalized software, net			5,800,000	6,600,000
Capitalized software costs, amortization			$ 1,607,000	$ 1,887,000	$ 2,405,000
Annual depreciation provisions expressed as a percentage of average depreciable property (in hundredths)			2.80%	2.72%	2.68%
Utility plants
Generation			$ 2,476,733,000	$ 2,442,987,000
Distribution			1,523,885,000	1,462,193,000
Transmission			731,432,000	725,199,000
Other utility plant			282,954,000	263,105,000
Total property, plant, and equipment			5,015,004,000	4,893,484,000
Accumulated depreciation			(1,804,563,000)	(1,712,590,000)
Net property, plant, and equipment			$ 3,210,441,000	$ 3,180,894,000