Regulatory Assets and Liabilities - Summary of Regulatory Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Jun. 30, 2019
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets, net	$ 423,279	$ 311,525
COVID-19 executive order
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	3,000
Deferred storm restoration costs - Hurricane Delta
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	17,100
Deferred storm restoration costs - Hurricane Zeta
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	3,500
Financing costs
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	7,592	7,935
Postretirement costs
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	15,411	17,399
Debt issuance costs
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	5,254	5,665
Fair value of long-term debt
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	119,553	127,977
CLECO POWER
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	456,034	306,172
Total regulatory liabilities	(180,565)	(153,623)
Total regulatory assets, net	275,469	152,549
CLECO POWER | AFUDC
Regulatory Assets and Liabilities [Line Items]
Total regulatory liabilities	(4,218)	0
CLECO POWER | Corporate franchise tax, net
Regulatory Assets and Liabilities [Line Items]
Total regulatory liabilities	(763)	(1,145)
CLECO POWER | Deferred taxes, net
Regulatory Assets and Liabilities [Line Items]
Total regulatory liabilities	(175,584)	(146,948)
CLECO POWER | Other
Regulatory Assets and Liabilities [Line Items]
Total regulatory liabilities	0	(834)
CLECO POWER | St. Mary Clean Energy Center
Regulatory Assets and Liabilities [Line Items]
Total regulatory liabilities	0	(4,696)	$ (9,600)
CLECO POWER | Acquisition costs or Transaction costs
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	$ 2,019	2,124
REMAINING RECOVERY PERIOD (YRS.)	19 years
CLECO POWER | Acquisition costs or Transaction costs | Natural Gas Processing Plant
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	$ 876	906
REMAINING RECOVERY PERIOD (YRS.)	28 years 6 months
CLECO POWER | Accumulated deferred fuel
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	$ 28,194	22,910
CLECO POWER | AFUDC equity gross-up
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	69,670	72,766
CLECO POWER | AMI deferred revenue requirement
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	$ 2,591	3,136
REMAINING RECOVERY PERIOD (YRS.)	5 years
CLECO POWER | AROs
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	$ 5,488	3,668
CLECO POWER | COVID-19 executive order
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	2,953	0
CLECO POWER | Deferred storm restoration costs - Hurricane Delta
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	17,051	0
CLECO POWER | Deferred storm restoration costs - Hurricane Laura
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	54,406	0
CLECO POWER | Deferred storm restoration costs - Hurricane Zeta
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	3,493	0
CLECO POWER | Accelerated depreciation | RODEMACHER UNIT 2
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	1,333	0
CLECO POWER | Accelerated depreciation | DOLET HILLS POWER STATION
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	48,982	0
CLECO POWER | Emergency declarations
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	$ 270	1,349
REMAINING RECOVERY PERIOD (YRS.)	6 months
CLECO POWER | Energy efficiency
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	$ 2,820	2,820
REMAINING RECOVERY PERIOD (YRS.)	2 years
CLECO POWER | Financing costs
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	$ 7,184	7,554
CLECO POWER | Interest costs
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	3,708	3,958
CLECO POWER | Non-service cost of postretirement benefits
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	9,901	6,739
CLECO POWER | Other
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	4,229	987
CLECO POWER | Other | Natural Gas Processing Plant
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	3,900
CLECO POWER | Postretirement costs
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	165,437	151,543
CLECO POWER | Production operations and maintenance expenses
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	4,058	7,985
CLECO POWER | St. Mary Clean Energy Center
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	3,479	0
CLECO POWER | Surcredits
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	0	145
CLECO POWER | Training costs
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	$ 6,085	6,241
REMAINING RECOVERY PERIOD (YRS.)	39 years
CLECO POWER | Tree trimming costs
Regulatory Assets and Liabilities [Line Items]
Total regulatory assets	$ 11,807	$ 11,341