Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning	$ 2,643,006	$ 2,124,740	$ 2,096,357
Amounts reclassified from accumulated other comprehensive income (loss)
Reclassification of effect of tax rate change			0
Balance, ending	2,757,023	2,643,006	2,124,740
CLECO POWER
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning	1,713,392	1,594,533	1,550,679
Other comprehensive income before reclassifications
Postretirement benefit adjustments incurred during the year	(4,050)	(10,344)	954
Amounts reclassified from accumulated other comprehensive income (loss)
Amortization of postretirement benefit net gain (loss)	1,628	687	1,789
Reclassification of net gain to interest charges	254	254	254
Reclassification of effect of tax rate change			0
Balance, ending	1,807,879	1,713,392	1,594,533
POSTRETIREMENT BENEFIT NET GAIN (LOSS)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning	(17,513)	1,786	(2,921)
Other comprehensive income before reclassifications
Postretirement benefit adjustments incurred during the year	(10,026)	(18,877)	3,681
Amounts reclassified from accumulated other comprehensive income (loss)
Amortization of postretirement benefit net gain (loss)	1,743	(422)	1,615
Reclassification of effect of tax rate change			(589)
Balance, ending	(25,796)	(17,513)	1,786
POSTRETIREMENT BENEFIT NET GAIN (LOSS) | CLECO POWER
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning	(16,717)	(7,060)	(8,377)
Other comprehensive income before reclassifications
Postretirement benefit adjustments incurred during the year	(4,050)	(10,344)	954
Amounts reclassified from accumulated other comprehensive income (loss)
Amortization of postretirement benefit net gain (loss)	1,628	687	1,789
Reclassification of net gain to interest charges	0	0	0
Reclassification of effect of tax rate change			(1,426)
Balance, ending	(19,139)	(16,717)	(7,060)
NET (LOSS) GAIN ON CASH FLOW HEDGES | CLECO POWER
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning	(5,868)	(6,122)	(5,306)
Other comprehensive income before reclassifications
Postretirement benefit adjustments incurred during the year	0	0	0
Amounts reclassified from accumulated other comprehensive income (loss)
Amortization of postretirement benefit net gain (loss)	0	0	0
Reclassification of net gain to interest charges	254	254	254
Reclassification of effect of tax rate change			(1,070)
Balance, ending	(5,614)	(5,868)	(6,122)
TOTAL AOCI
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning	(17,513)	1,786	(2,921)
Amounts reclassified from accumulated other comprehensive income (loss)
Reclassification of effect of tax rate change			(589)
Balance, ending	(25,796)	(17,513)	1,786
TOTAL AOCI | CLECO POWER
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning	(22,585)	(13,182)	(13,683)
Amounts reclassified from accumulated other comprehensive income (loss)
Reclassification of effect of tax rate change			(2,496)
Balance, ending	$ (24,753)	$ (22,585)	$ (13,182)