Summary of Significant Accounting Policies - Changes in Allowance for Credit Losses (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)
Accounting Policies [Line Items]
Receivable, threshold period past due	20 days
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balances, Dec. 31, 2019	$ 3,005
Current period provision	5,029
Charge-offs	(6,423)
Recovery	1,076
Balances, Dec. 31, 2020	2,758
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balances, Dec. 31, 2019	1,250
Current period provision	388
Charge-offs	0
Recovery	0
Balances, Dec. 31, 2020	1,638
Receivable, Allowance For Credit Loss [Roll Forward]
Balances, Dec. 31, 2019	4,255
Current period provision	5,417
Charge-offs	(6,423)
Recovery	1,076
Balances, Dec. 31, 2020	4,396
Accounting Standards Update 2016-13 | CECL adoption
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balances, Dec. 31, 2019	71
Receivable, Allowance For Credit Loss [Roll Forward]
Balances, Dec. 31, 2019	$ 71
Cleco Power
Accounting Policies [Line Items]
Past due balances, repayment plan, period	18 months
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balances, Dec. 31, 2019	$ 3,005
Current period provision	5,029
Charge-offs	(6,423)
Recovery	1,076
Balances, Dec. 31, 2020	2,758
Cleco Power | Accounting Standards Update 2016-13 | CECL adoption
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balances, Dec. 31, 2019	$ 71