Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended		12 Months Ended
	Apr. 12, 2016	Dec. 31, 2016	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Predecessor [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balances. Beginning	$ 1,674,841		$ 1,646,061		$ 1,674,841	$ 1,627,270
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]
Total other comprehensive income (loss), net of tax	647					6,080
Balances, Ending	1,646,061					1,674,841
Successor [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balances, Beginning		$ 2,158,141		$ 2,046,763
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]
Total other comprehensive income (loss), net of tax		1,500	1,500	(4,421)
Balances, Ending		2,046,763	2,046,763	2,096,357	2,046,763
Cleco Power [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balances, Beginning	1,552,404			1,535,202	1,552,404	1,545,858
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]
Total other comprehensive income (loss), net of tax				(261)	3,670	196
Balances, Ending		1,535,202	1,535,202	1,550,679	1,535,202	1,552,404
Postretirement Benefit Net (Loss) Gain | Predecessor [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balances. Beginning	(20,857)		(20,270)		(20,857)	(26,726)
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]
Postretirement benefit adjustments during the period						2,790
Amounts reclassified from accumulated other comprehensive income (loss)	587					3,079
Total other comprehensive income (loss), net of tax	587					5,869
Balances, Ending	(20,270)					(20,857)
Postretirement Benefit Net (Loss) Gain | Successor [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balances, Beginning		0		1,500
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]
Postretirement benefit adjustments during the period		2,304		(3,898)
Amounts reclassified from accumulated other comprehensive income (loss)		(804)		(523)
Total other comprehensive income (loss), net of tax		1,500		(4,421)
Balances, Ending		1,500	1,500	(2,921)	1,500
Postretirement Benefit Net (Loss) Gain | Cleco Power [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balances, Beginning	(11,364)			(7,905)	(11,364)	(11,349)
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]
Postretirement benefit adjustments during the period				(948)	3,913	(1,232)
Amounts reclassified from accumulated other comprehensive income (loss)				476	(454)	1,217
Total other comprehensive income (loss), net of tax				(472)	3,459	(15)
Balances, Ending		(7,905)	(7,905)	(8,377)	(7,905)	(11,364)
Net (Loss) Gain on Cash Flow Hedges | Predecessor [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balances. Beginning	(5,728)		(5,668)		(5,728)	(5,939)
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]
Total other comprehensive income (loss), net of tax	60					211
Balances, Ending	(5,668)					(5,728)
Net (Loss) Gain on Cash Flow Hedges | Successor [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balances, Beginning		0		0
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]
Total other comprehensive income (loss), net of tax		0		0
Balances, Ending		0	0	0	0
Net (Loss) Gain on Cash Flow Hedges | Cleco Power [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balances, Beginning	(5,728)			(5,517)	(5,728)	(5,939)
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]
Total other comprehensive income (loss), net of tax				211	211	211
Balances, Ending		(5,517)	(5,517)	(5,306)	(5,517)	(5,728)
Total AOCI | Predecessor [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balances. Beginning	(26,585)		(25,938)		(26,585)	(32,665)
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]
Postretirement benefit adjustments during the period						2,790
Amounts reclassified from accumulated other comprehensive income (loss)	587					3,079
Total other comprehensive income (loss), net of tax	647					6,080
Balances, Ending	(25,938)					(26,585)
Total AOCI | Successor [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balances, Beginning		0		1,500
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]
Postretirement benefit adjustments during the period		2,304		(3,898)
Amounts reclassified from accumulated other comprehensive income (loss)		(804)		(523)
Total other comprehensive income (loss), net of tax		1,500		(4,421)
Balances, Ending		1,500	1,500	(2,921)	1,500
Total AOCI | Cleco Power [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balances, Beginning	(17,092)			(13,422)	(17,092)	(17,288)
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]
Postretirement benefit adjustments during the period				(948)	3,913	(1,232)
Amounts reclassified from accumulated other comprehensive income (loss)				476	(454)	1,217
Total other comprehensive income (loss), net of tax				(261)	3,670	196
Balances, Ending		$ (13,422)	$ (13,422)	(13,683)	(13,422)	(17,092)
Interest Expense [Member] | Net (Loss) Gain on Cash Flow Hedges | Predecessor [Member]
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]
Amounts reclassified from accumulated other comprehensive income (loss)	60					211
Interest Expense [Member] | Net (Loss) Gain on Cash Flow Hedges | Cleco Power [Member]
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]
Amounts reclassified from accumulated other comprehensive income (loss)				211	211	211
Interest Expense [Member] | Total AOCI | Predecessor [Member]
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]
Amounts reclassified from accumulated other comprehensive income (loss)	$ 60					211
Interest Expense [Member] | Total AOCI | Cleco Power [Member]
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]
Amounts reclassified from accumulated other comprehensive income (loss)				$ 211	$ 211	$ 211