Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	$ 2,693,358	$ 2,574,661	$ 2,643,006	$ 2,124,740
Balances, end of period	2,754,103	2,630,189	2,754,103	2,630,189
TOTAL AOCI
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(16,657)	1,504	(17,513)	1,786
Balances, end of period	(16,209)	1,467	(16,209)	1,467
POSTRETIREMENT BENEFIT NET LOSS
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(16,657)	1,504	(17,513)	1,786
Amounts reclassified from AOCI	448	(37)	1,304	(319)
Balances, end of period	(16,209)	1,467	(16,209)	1,467
CLECO POWER
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	1,754,429	1,671,014	1,713,392	1,594,533
Balances, end of period	1,790,957	1,722,834	1,790,957	1,722,834
CLECO POWER | TOTAL AOCI
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(21,612)	(12,769)	(22,585)	(13,182)
Balances, end of period	(21,176)	(12,476)	(21,176)	(12,476)
CLECO POWER | POSTRETIREMENT BENEFIT NET LOSS
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(15,872)	(6,775)	(16,717)	(7,060)
Amounts reclassified from AOCI	373	230	1,218	515
Balances, end of period	(15,499)	(6,545)	(15,499)	(6,545)
CLECO POWER | NET LOSS ON CASH FLOW HEDGES
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(5,740)	(5,994)	(5,868)	(6,122)
Amounts reclassified from AOCI	63	63	191	191
Balances, end of period	$ (5,677)	$ (5,931)	$ (5,677)	$ (5,931)