Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	$ 2,574,661	$ 2,093,447	$ 2,124,740	$ 2,096,357
Amounts reclassified from accumulated AOCI
Balances, end of period	2,630,189	2,120,468	2,630,189	2,120,468
TOTAL AOCI
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	1,504	(2,631)	1,786	(2,921)
Amounts reclassified from accumulated AOCI
Balances, end of period	1,467	(2,370)	1,467	(2,370)
POSTRETIREMENT BENEFIT NET LOSS
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	1,504	(2,631)	1,786	(2,921)
Amounts reclassified from accumulated AOCI
Amounts reclassified from AOCI	(37)	261	(319)	551
Balances, end of period	1,467	(2,370)	1,467	(2,370)
CLECO POWER
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	1,671,014	1,549,331	1,594,533	1,550,679
Amounts reclassified from accumulated AOCI
Balances, end of period	1,722,834	1,562,690	1,722,834	1,562,690
CLECO POWER | TOTAL AOCI
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(12,769)	(13,055)	(13,182)	(13,683)
Amounts reclassified from accumulated AOCI
Balances, end of period	(12,476)	(12,631)	(12,476)	(12,631)
CLECO POWER | POSTRETIREMENT BENEFIT NET LOSS
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(6,775)	(7,877)	(7,060)	(8,377)
Amounts reclassified from accumulated AOCI
Amounts reclassified from AOCI	230	312	515	812
Balances, end of period	(6,545)	(7,565)	(6,545)	(7,565)
CLECO POWER | NET LOSS ON CASH FLOW HEDGES
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(5,994)	(5,178)	(6,122)	(5,306)
Amounts reclassified from accumulated AOCI
Amounts reclassified from AOCI	63	112	191	240
Balances, end of period	$ (5,931)	$ (5,066)	$ (5,931)	$ (5,066)