Regulatory Assets and Liabilities - Schedule of Regulatory Assets (Details) customer in Thousands, $ in Thousands	Sep. 30, 2020 USD ($)	Aug. 27, 2020 customer	Dec. 31, 2019 USD ($)
Financing costs
Regulatory Assets [Line Items]
Regulatory assets	$ 7,677		$ 7,935
Postretirement costs
Regulatory Assets [Line Items]
Regulatory assets	15,908		17,399
Fair value of long-term debt
Regulatory Assets [Line Items]
Regulatory assets	121,404		127,977
Debt issuance costs
Regulatory Assets [Line Items]
Regulatory assets	5,337		5,665
CLECO POWER | Hurricane Laura
Regulatory Assets [Line Items]
Number of customers affected with power outage | customer		140
CLECO POWER | Acquisition/ transaction costs
Regulatory Assets [Line Items]
Regulatory assets	2,045		2,124
CLECO POWER | Acquisition/ transaction costs | Coughlin transaction costs
Regulatory Assets [Line Items]
Regulatory assets	884		906
CLECO POWER | Accumulated deferred fuel
Regulatory Assets [Line Items]
Regulatory assets	43,612		22,910
CLECO POWER | AFUDC equity gross-up
Regulatory Assets [Line Items]
Regulatory assets	70,444		72,766
CLECO POWER | AMI deferred revenue requirement
Regulatory Assets [Line Items]
Regulatory assets	2,727		3,136
CLECO POWER | AROs
Regulatory Assets [Line Items]
Regulatory assets	4,805		3,668
CLECO POWER | COVID-19 executive order
Regulatory Assets [Line Items]
Regulatory assets	2,953		0
CLECO POWER | Deferred storm restoration costs — Hurricane Laura
Regulatory Assets [Line Items]
Regulatory assets	57,669		0
CLECO POWER | Dolet Hills closure costs
Regulatory Assets [Line Items]
Regulatory assets	28,635		0
CLECO POWER | Emergency declarations
Regulatory Assets [Line Items]
Regulatory assets	408		1,349
CLECO POWER | Energy efficiency
Regulatory Assets [Line Items]
Regulatory assets	2,820		2,820
CLECO POWER | Financing costs
Regulatory Assets [Line Items]
Regulatory assets	7,276		7,554
CLECO POWER | Interest costs
Regulatory Assets [Line Items]
Regulatory assets	3,771		3,958
CLECO POWER | Non-service cost of postretirement benefits
Regulatory Assets [Line Items]
Regulatory assets	8,891		6,739
CLECO POWER | Other, net
Regulatory Assets [Line Items]
Regulatory assets	3,206		153
CLECO POWER | Postretirement costs
Regulatory Assets [Line Items]
Regulatory assets	139,369		151,543
CLECO POWER | Production operations and maintenance expenses
Regulatory Assets [Line Items]
Regulatory assets	4,754		7,985
CLECO POWER | St. Mary Clean Energy Center
Regulatory Assets [Line Items]
Regulatory assets	1,740
CLECO POWER | Surcredits, net
Regulatory Assets [Line Items]
Regulatory assets	0		145
CLECO POWER | Training costs
Regulatory Assets [Line Items]
Regulatory assets	6,124		6,241
CLECO POWER | Tree trimming costs
Regulatory Assets [Line Items]
Regulatory assets	$ 12,241		$ 11,341