Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	$ 2,777,978	$ 2,649,748	$ 2,757,023	$ 2,643,006
Balances, end of period	2,856,380	2,693,358	2,856,380	2,693,358
TOTAL AOCI
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(25,168)	(17,099)	(25,796)	(17,513)
Balances, end of period	(25,588)	(16,657)	(25,588)	(16,657)
POSTRETIREMENT BENEFIT NET LOSS
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(25,168)	(17,099)	(25,796)	(17,513)
Amounts reclassified from AOCI	(420)	442	208	856
Balances, end of period	(25,588)	(16,657)	(25,588)	(16,657)
CLECO POWER
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	1,826,826	1,725,713	1,807,879	1,713,392
Balances, end of period	1,854,598	1,754,429	1,854,598	1,754,429
CLECO POWER | TOTAL AOCI
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(24,231)	(22,095)	(24,753)	(22,585)
Balances, end of period	(23,880)	(21,612)	(23,880)	(21,612)
CLECO POWER | POSTRETIREMENT BENEFIT NET LOSS
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(18,681)	(16,291)	(19,139)	(16,717)
Amounts reclassified from AOCI	287	419	745	845
Balances, end of period	(18,394)	(15,872)	(18,394)	(15,872)
CLECO POWER | NET LOSS ON CASH FLOW HEDGES
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(5,550)	(5,804)	(5,614)	(5,868)
Amounts reclassified from AOCI	64	64	128	128
Balances, end of period	$ (5,486)	$ (5,740)	$ (5,486)	$ (5,740)