Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	$ 2,856,380	$ 2,693,358	$ 2,757,023	$ 2,643,006
Balances, end of period	2,976,386	2,754,103	2,976,386	2,754,103
TOTAL AOCI
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(25,588)	(16,657)	(25,796)	(17,513)
Balances, end of period	(25,492)	(16,209)	(25,492)	(16,209)
POSTRETIREMENT BENEFIT NET LOSS
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(25,588)	(16,657)	(25,796)	(17,513)
Amounts reclassified from AOCI	96	448	304	1,304
Balances, end of period	(25,492)	(16,209)	(25,492)	(16,209)
CLECO POWER
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	1,854,598	1,754,429	1,807,879	1,713,392
Balances, end of period	1,911,572	1,790,957	1,911,572	1,790,957
CLECO POWER | TOTAL AOCI
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(23,880)	(21,612)	(24,753)	(22,585)
Balances, end of period	(23,467)	(21,176)	(23,467)	(21,176)
CLECO POWER | POSTRETIREMENT BENEFIT NET LOSS
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(18,394)	(15,872)	(19,139)	(16,717)
Amounts reclassified from AOCI	350	373	1,095	1,218
Balances, end of period	(18,044)	(15,499)	(18,044)	(15,499)
CLECO POWER | NET LOSS ON CASH FLOW HEDGES
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(5,486)	(5,740)	(5,614)	(5,868)
Amounts reclassified from AOCI	63	63	191	191
Balances, end of period	$ (5,423)	$ (5,677)	$ (5,423)	$ (5,677)