Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	$ 2,649,748	$ 2,530,062	$ 2,643,006	$ 2,124,740
Balances, end of period	2,693,358	2,574,661	2,693,358	2,574,661
TOTAL AOCI
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(17,099)	1,651	(17,513)	1,786
Balances, end of period	(16,657)	1,504	(16,657)	1,504
POSTRETIREMENT BENEFIT NET LOSS
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(17,099)	1,651	(17,513)	1,786
Amounts reclassified from AOCI	442	(147)	856	(282)
Balances, end of period	(16,657)	1,504	(16,657)	1,504
CLECO POWER
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	1,725,713	1,621,465	1,713,392	1,594,533
Balances, end of period	1,754,429	1,671,014	1,754,429	1,671,014
CLECO POWER | TOTAL AOCI
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(22,095)	(12,962)	(22,585)	(13,182)
Balances, end of period	(21,612)	(12,769)	(21,612)	(12,769)
CLECO POWER | POSTRETIREMENT BENEFIT NET LOSS
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(16,291)	(6,904)	(16,717)	(7,060)
Amounts reclassified from AOCI	419	129	845	285
Balances, end of period	(15,872)	(6,775)	(15,872)	(6,775)
CLECO POWER | NET LOSS ON CASH FLOW HEDGES
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(5,804)	(6,058)	(5,868)	(6,122)
Amounts reclassified from AOCI	64	64	128	128
Balances, end of period	$ (5,740)	$ (5,994)	$ (5,740)	$ (5,994)