Income Taxes, Effective Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Apr. 12, 2016	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Successor [Member]
Income tax reconciliation [Abstract]
Income before tax		$ (46,935)	$ 145,159
Statutory rate (in hundredths)		35.00%	35.00%
Tax at federal statutory rate		$ (16,427)	$ 50,806
Increase (decrease):
Plant differences, including AFUDC flowthrough		(881)	743
Amortization of investment tax credits		(371)	(662)
State income taxes		(4,725)	4,254
Nondeductible merger costs		(844)	2
Return to accrual adjustment		(2,943)	(608)
2017 tax reform		0	(46,291)
NMTC		(181)	313
Other		3,550	(1,478)
Total taxes		$ (22,822)	$ 7,079
Effective Rate (in hundredths)		48.60%	4.90%
Predecessor [Member]
Income tax reconciliation [Abstract]
Income before tax	$ (492)				$ 211,373
Statutory rate (in hundredths)	35.00%				35.00%
Tax at federal statutory rate	$ (172)				$ 73,981
Increase (decrease):
Plant differences, including AFUDC flowthrough	823				1,875
Amortization of investment tax credits	(124)				(916)
State income taxes	(3,078)				1,117
Nondeductible merger costs	4,282				0
Return to accrual adjustment	0				0
2017 tax reform	0				0
NMTC	(158)				243
Other	1,895				1,404
Total taxes	$ 3,468				$ 77,704
Effective Rate (in hundredths)	(704.90%)				36.80%
Cleco Power [Member]
Income tax reconciliation [Abstract]
Income before tax			$ 218,069	$ 57,497	$ 220,644
Statutory rate (in hundredths)			35.00%	35.00%	35.00%
Tax at federal statutory rate			$ 76,324	$ 20,124	$ 77,225
Increase (decrease):
Plant differences, including AFUDC flowthrough			743	(58)	1,875
Amortization of investment tax credits			(662)	(494)	(916)
State income taxes			8,156	(2,573)	1,501
Return to accrual adjustment			(284)	(2,646)	0
2017 tax reform			(14,292)	0	0
Other			(2,654)	4,016	(391)
Total taxes			$ 67,331	$ 18,369	$ 79,294
Effective Rate (in hundredths)			30.90%	31.90%	35.90%