Fair Value Accounting, Fair Value Measurements and Disclosures (Details)	3 Months Ended	9 Months Ended	12 Months Ended
	Apr. 12, 2016 USD ($)	Dec. 31, 2016 USD ($) $ / MW	Dec. 31, 2017 USD ($) $ / MW	Dec. 31, 2016 USD ($) $ / MW
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
FTR Forward Price - per MWh, Low | $ / MW		(3.61)	(2.95)	(3.61)
FTR Forward Price - per MWh, High | $ / MW		6.04	6.33	6.04
Fair Value, Concentration of Risk, Amount of Money Market Funds in Cash and Cash Equivalents		$ 20,000,000	$ 111,100,000	$ 20,000,000
Fair Value, Assets and Liabilities, Transfers between Levels, Amount		$ 0	$ 0	$ 0
Cleco Power [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
FTR Forward Price - per MWh, Low | $ / MW		(3.61)	(2.95)	(3.61)
FTR Forward Price - per MWh, High | $ / MW		6.04	6.33	6.04
Fair Value, Concentration of Risk, Amount of Money Market Funds in Cash and Cash Equivalents		$ 18,700,000	$ 62,500,000	$ 18,700,000
FTRs [Member] | Cleco Power [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	$ 7,398,000		7,683,000	7,398,000
Unrealized gains (losses)			(1,392,000)	2,088,000
Purchases			23,941,000	14,966,000
Settlements			(23,188,000)	(16,769,000)
Ending balance		7,683,000	7,044,000	7,683,000
Measured On A Recurring Basis [Member]
Asset Description
Institutional money market funds		66,410,000	144,302,000	66,410,000
FTR assets		7,884,000	7,396,000	7,884,000
Total Assets		74,294,000	151,698,000	74,294,000
Liability Description
FTR liabilities		201,000	352,000	201,000
Total Liabilities		201,000	352,000	201,000
Measured On A Recurring Basis [Member] | Cleco Power [Member]
Asset Description
Institutional money market funds		65,089,000	95,681,000	65,089,000
FTR assets		7,884,000	7,396,000	7,884,000
Total Assets		72,973,000	103,077,000	72,973,000
Liability Description
FTR liabilities		201,000	352,000	201,000
Total Liabilities		201,000	352,000	201,000
Measured On A Recurring Basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Asset Description
Institutional money market funds		0	0	0
FTR assets		0	0	0
Total Assets		0	0	0
Liability Description
FTR liabilities		0	0	0
Total Liabilities		0	0	0
Measured On A Recurring Basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Cleco Power [Member]
Asset Description
Institutional money market funds		0	0	0
FTR assets		0	0	0
Total Assets		0	0	0
Liability Description
FTR liabilities		0	0	0
Total Liabilities		0	0	0
Measured On A Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member]
Asset Description
Institutional money market funds		66,410,000	144,302,000	66,410,000
FTR assets		0	0	0
Total Assets		66,410,000	144,302,000	66,410,000
Liability Description
FTR liabilities		0	0	0
Total Liabilities		0	0	0
Measured On A Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Cleco Power [Member]
Asset Description
Institutional money market funds		65,089,000	95,681,000	65,089,000
FTR assets		0	0	0
Total Assets		65,089,000	95,681,000	65,089,000
Liability Description
FTR liabilities		0	0	0
Total Liabilities		0	0	0
Measured On A Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member]
Asset Description
Institutional money market funds		0	0	0
FTR assets		7,884,000	7,396,000	7,884,000
Total Assets		7,884,000	7,396,000	7,884,000
Liability Description
FTR liabilities		201,000	352,000	201,000
Total Liabilities		201,000	352,000	201,000
Measured On A Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member] | Cleco Power [Member]
Asset Description
Institutional money market funds		0	0	0
FTR assets		7,884,000	7,396,000	7,884,000
Total Assets		7,884,000	7,396,000	7,884,000
Liability Description
FTR liabilities		201,000	352,000	201,000
Total Liabilities		201,000	352,000	201,000
Restricted Cash and Cash Equivalents, Current [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Fair Value, Concentration of Risk, Amount of Money Market Funds in Institutional Money Market Funds		23,100,000	13,100,000	23,100,000
Restricted Cash and Cash Equivalents, Current [Member] | Cleco Power [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Fair Value, Concentration of Risk, Amount of Money Market Funds in Institutional Money Market Funds		23,100,000	13,100,000	23,100,000
Restricted Cash and Cash Equivalents, Noncurrent [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Fair Value, Concentration of Risk, Amount of Money Market Funds in Institutional Money Market Funds		23,300,000	20,100,000	23,300,000
Restricted Cash and Cash Equivalents, Noncurrent [Member] | Cleco Power [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Fair Value, Concentration of Risk, Amount of Money Market Funds in Institutional Money Market Funds		23,300,000	20,100,000	23,300,000
Successor [Member] | FTRs [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance		3,458,000	7,683,000
Unrealized gains (losses)		3,119,000	(1,392,000)
Purchases		12,896,000	23,941,000
Settlements		(11,790,000)	(23,188,000)
Ending balance	3,458,000	7,683,000	$ 7,044,000	7,683,000
Predecessor [Member] | FTRs [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	7,398,000	$ 3,458,000		$ 7,398,000
Unrealized gains (losses)	(1,031,000)
Purchases	2,070,000
Settlements	(4,979,000)
Ending balance	$ 3,458,000