Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	$ 2,757,023	$ 2,643,006
Balances, end of period	2,777,978	2,649,748
TOTAL AOCI
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(25,796)	(17,513)
Balances, end of period	(25,168)	(17,099)
POSTRETIREMENT BENEFIT NET LOSS
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(25,796)	(17,513)
Amounts reclassified from AOCI	628	414
Balances, end of period	(25,168)	(17,099)
CLECO POWER
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	1,807,879	1,713,392
Balances, end of period	1,826,826	1,725,713
CLECO POWER | TOTAL AOCI
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(24,753)	(22,585)
Balances, end of period	(24,231)	(22,095)
CLECO POWER | POSTRETIREMENT BENEFIT NET LOSS
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(19,139)	(16,717)
Amounts reclassified from AOCI	458	426
Balances, end of period	(18,681)	(16,291)
CLECO POWER | NET LOSS ON CASH FLOW HEDGES
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(5,614)	(5,868)
Amounts reclassified from AOCI	64	64
Balances, end of period	$ (5,550)	$ (5,804)