Debt - Total Indebtedness (Details) - USD ($) $ in Thousands	Dec. 31, 2020	May 01, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Total Long-term debt and finance Leases, net	$ 3,165,387		$ 3,064,679
Finance	682		617
Unamortized debt issuance costs	(13,400)		(13,700)
Cleco Power
Debt Instrument [Line Items]
Total Long-term debt and finance Leases, net	1,502,257		1,327,372
Total bonds	1,375,000		1,386,055
Barge lease obligations	15,244		15,861
Gross amount of long-term debt and finance leases	1,515,244		1,401,916
Less: long-term debt due within one year	0		60,970
Finance	682		617
Unamortized debt discount	(5,053)		(5,368)
Unamortized debt issuance costs	(7,252)		(7,589)
Unamortized debt issuance costs	(7,000)		(7,400)
Cleco Power | Senior notes, 2.94%, due 2022
Debt Instrument [Line Items]
Total bonds	$ 25,000		25,000
Interest rate	2.94%
Cleco Power | Senior notes, 3.08%, due 2023
Debt Instrument [Line Items]
Total bonds	$ 100,000		100,000
Interest rate	3.08%
Cleco Power | Senior notes, 3.17%, due 2024
Debt Instrument [Line Items]
Total bonds	$ 50,000		50,000
Interest rate	3.17%
Cleco Power | Senior notes, 3.68%, due 2025
Debt Instrument [Line Items]
Total bonds	$ 75,000		75,000
Interest rate	3.68%
Cleco Power | Senior notes, 3.47%, due 2026
Debt Instrument [Line Items]
Total bonds	$ 130,000		130,000
Interest rate	3.47%
Cleco Power | Senior notes, 4.33%, due 2027
Debt Instrument [Line Items]
Total bonds	$ 50,000		50,000
Interest rate	4.33%
Cleco Power | Senior notes, 3.57%, due 2028
Debt Instrument [Line Items]
Total bonds	$ 200,000		200,000
Interest rate	3.57%
Cleco Power | Senior notes, 6.50%, due 2035
Debt Instrument [Line Items]
Total bonds	$ 295,000		295,000
Interest rate	6.50%
Cleco Power | Senior notes, 6.00%, due 2040
Debt Instrument [Line Items]
Total bonds	$ 250,000		250,000
Interest rate	6.00%
Cleco Power | Senior notes, 5.12%, due 2041
Debt Instrument [Line Items]
Total bonds	$ 100,000		100,000
Interest rate	5.12%
Cleco Power | Series A GO Zone bonds, 2.50%, due 2038, mandatory tender in 2025
Debt Instrument [Line Items]
Total bonds	$ 50,000		50,000
Interest rate	2.50%	2.50%
Cleco Power | Series B GO Zone bonds, 4.25%, due 2038
Debt Instrument [Line Items]
Total bonds	$ 50,000		50,000
Interest rate	4.25%
Cleco Power | Cleco Katrina/Rita’s storm recovery bonds, 5.61%, due 2023
Debt Instrument [Line Items]
Total bonds	$ 0		11,055
Interest rate	5.61%
Cleco Power | Bank term loan, variable rate, due 2022
Debt Instrument [Line Items]
Bank term loan, variable rate, due 2022	$ 125,000		0
Cleco Holdings
Debt Instrument [Line Items]
Unamortized debt issuance costs	(11,700)		(11,900)
Long-term debt due within one year	(66,000)		(64,398)
Unamortized debt issuance costs	(6,423)		(6,271)
Fair value adjustment	119,553		127,976
Deferred debt issuance costs eliminated as a result of the 2016 Merger	5,300		5,600
Cleco Holdings | Senior notes, 3.250%, due 2023
Debt Instrument [Line Items]
Total bonds	$ 165,000		165,000
Interest rate	3.25%
Cleco Holdings | Senior notes, 3.743%, due 2026
Debt Instrument [Line Items]
Total bonds	$ 535,000		535,000
Interest rate	3.743%
Cleco Holdings | Senior notes, 3.375%, due 2029
Debt Instrument [Line Items]
Total bonds	$ 300,000		300,000
Interest rate	3.375%
Cleco Holdings | Senior notes, 4.973%, due 2046
Debt Instrument [Line Items]
Total bonds	$ 350,000		350,000
Interest rate	4.973%
Cleco Holdings | Bank term loan, due 2022
Debt Instrument [Line Items]
Bank term loan, variable rate, due 2022	$ 266,000		300,000
Cleco Holdings | Bank term loan two, due 2022
Debt Instrument [Line Items]
Bank term loan, variable rate, due 2022	$ 0		$ 30,000