Regulatory Assets and Liabilities - Narrative (Details) customer in Thousands		1 Months Ended		12 Months Ended
	Apr. 13, 2016 instrument	Jan. 31, 2019 USD ($)	May 31, 2013 USD ($)	Dec. 31, 2020 USD ($)	Jun. 30, 2020	Dec. 31, 2011 USD ($) treasury_rate_lock	Oct. 28, 2020 customer	Oct. 09, 2020 customer	Aug. 27, 2020 customer	Dec. 31, 2019 USD ($)	Jun. 30, 2019 USD ($)	Oct. 31, 2016 USD ($)
Excess A D I T | LPSC
Regulatory Assets and Liabilities [Line Items]
Regulatory liability				$ 352,400,000						$ 375,000,000.0
Treasury Lock
Regulatory Assets and Liabilities [Line Items]
Number of instruments settled | instrument	2
AMI deferred revenue requirement
Regulatory Assets and Liabilities [Line Items]
Regulatory assets amortization period (in years/months)				11 years
COVID-19 executive order
Regulatory Assets and Liabilities [Line Items]
Regulatory assets amortization period (in years/months)				4 years
Total regulatory assets				$ 3,000,000.0
Financing costs
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets				7,592,000						7,935,000
Postretirement costs
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets				15,411,000						17,399,000
CLECO POWER
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets				456,034,000						306,172,000
Annual reduction to retail customer rates		$ 4,000,000.0
Regulatory liability				180,565,000						153,623,000
CLECO POWER | Deferred storm restoration costs - Hurricane Laura
Regulatory Assets and Liabilities [Line Items]
Number of customers affected with power outage | customer									140,000
CLECO POWER | Deferred storm restoration costs - Hurricane Delta
Regulatory Assets and Liabilities [Line Items]
Number of customers affected with power outage | customer								132,000
CLECO POWER | Deferred storm restoration costs - Hurricane Zeta
Regulatory Assets and Liabilities [Line Items]
Number of customers affected with power outage | customer							73,000
CLECO POWER | St. Mary Clean Energy Center
Regulatory Assets and Liabilities [Line Items]
Regulatory liability				$ 0						4,696,000	$ 9,600,000
CLECO POWER | Corporate franchise tax, net
Regulatory Assets and Liabilities [Line Items]
Regulatory liabilities amortization period (in years/months)				12 months
Regulatory liability				$ 763,000						1,145,000
CLECO POWER | Excess A D I T | LPSC
Regulatory Assets and Liabilities [Line Items]
Regulatory liability				352,400,000						375,000,000.0
CLECO POWER | AFUDC
Regulatory Assets and Liabilities [Line Items]
Regulatory liability				$ 4,218,000						0
CLECO POWER | Treasury Lock
Regulatory Assets and Liabilities [Line Items]
Number of treasury locks | treasury_rate_lock						2
Loss on settlements						$ 26,800,000
CLECO POWER | Interest Rate Swap
Regulatory Assets and Liabilities [Line Items]
Loss on settlements			$ 3,300,000
CLECO POWER | Acquisition costs or transaction costs
Regulatory Assets and Liabilities [Line Items]
Regulatory assets amortization period (in years/months)				30 years
Total regulatory assets				$ 2,019,000						2,124,000
CLECO POWER | Acquisition costs or transaction costs | Natural Gas Processing Plant
Regulatory Assets and Liabilities [Line Items]
Regulatory assets amortization period (in years/months)				35 years
Total regulatory assets				$ 876,000						906,000
CLECO POWER | Accumulated deferred fuel
Regulatory Assets and Liabilities [Line Items]
Percentage of total fuel cost regulated by the LPSC (in hundredths)				76.00%
Total regulatory assets				$ 28,194,000						22,910,000
CLECO POWER | AMI deferred revenue requirement
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets				2,591,000						3,136,000
CLECO POWER | COVID-19 executive order
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets				$ 2,953,000						0
CLECO POWER | Accelerated depreciation | DOLET HILLS POWER STATION
Regulatory Assets and Liabilities [Line Items]
Regulatory assets amortization period (in years/months)				20 years
Total regulatory assets				$ 48,982,000						0
CLECO POWER | Accelerated depreciation | RODEMACHER UNIT 2
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets				$ 1,333,000						0
CLECO POWER | Energy efficiency
Regulatory Assets and Liabilities [Line Items]
Regulatory assets amortization period (in years/months)				4 years
Total regulatory assets				$ 2,820,000						2,820,000
CLECO POWER | Financing costs
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets				7,184,000						7,554,000
CLECO POWER | Financing costs | Treasury Lock
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets						$ 7,400,000
CLECO POWER | Financing costs | Interest Rate Swap
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets			$ 2,900,000
CLECO POWER | Other
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets				4,229,000						987,000
CLECO POWER | Other | Natural Gas Processing Plant
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets				3,900,000
CLECO POWER | Other | Other
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets				$ 300,000
CLECO POWER | Postretirement costs
Regulatory Assets and Liabilities [Line Items]
Regulatory assets amortization period (in years/months)				7 years
Total regulatory assets				$ 165,437,000						151,543,000
CLECO POWER | Production O&M Expenses
Regulatory Assets and Liabilities [Line Items]
Regulatory assets amortization period (in years/months)				3 years
Retail jurisdictional portion				$ 45,000,000.0
CLECO POWER | Production O&M Expenses | MAXIMUM
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets				23,000,000.0
CLECO POWER | St. Mary Clean Energy Center
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets				$ 3,479,000						0
CLECO POWER | Surcredits
Regulatory Assets and Liabilities [Line Items]
Regulatory assets amortization period (in years/months)				4 years
Total regulatory assets				$ 0						145,000
CLECO POWER | Training costs
Regulatory Assets and Liabilities [Line Items]
Regulatory assets amortization period (in years/months)				50 years
Total regulatory assets				$ 6,085,000						6,241,000
CLECO POWER | Tree trimming costs
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets				$ 11,807,000						$ 11,341,000
Maximum amount of costs approved to defer												$ 10,900,000
Cleco Cajun | LPSC 2016-2017 Fuel Audit
Regulatory Assets and Liabilities [Line Items]
Annual reduction to retail customer rates		$ 4,000,000.0
Regulatory liabilities amortization period (in years/months)					12 months