Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	$ 2,643,006	$ 2,124,740
Amounts reclassified from accumulated AOCI
Balances, end of period	2,649,748	2,530,062
TOTAL AOCI
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(17,513)	1,786
Amounts reclassified from accumulated AOCI
Balances, end of period	(17,099)	1,651
POSTRETIREMENT BENEFIT NET LOSS
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(17,513)	1,786
Amounts reclassified from accumulated AOCI
Amounts reclassified from AOCI	414	(135)
Balances, end of period	(17,099)	1,651
CLECO POWER
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	1,713,392	1,594,533
Amounts reclassified from accumulated AOCI
Balances, end of period	1,725,713	1,621,465
CLECO POWER | TOTAL AOCI
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(22,585)	(13,182)
Amounts reclassified from accumulated AOCI
Balances, end of period	(22,095)	(12,962)
CLECO POWER | POSTRETIREMENT BENEFIT NET LOSS
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(16,717)	(7,060)
Amounts reclassified from accumulated AOCI
Amounts reclassified from AOCI	426	156
Balances, end of period	(16,291)	(6,904)
CLECO POWER | NET LOSS ON CASH FLOW HEDGES
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances, beginning of period	(5,868)	(6,122)
Amounts reclassified from accumulated AOCI
Amounts reclassified from AOCI	64	64
Balances, end of period	$ (5,804)	$ (6,058)