Pension Plan and Employee Benefits - Narrative (Details)		3 Months Ended	9 Months Ended	12 Months Ended
	Mar. 30, 2017 USD ($)	Apr. 12, 2016 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($) bonus executive_officer	Dec. 31, 2017 USD ($) executive_officer	Dec. 31, 2016 USD ($)	Mar. 29, 2017	Aug. 31, 2016 executive_officer	Apr. 13, 2016
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefit obligations					$ 249,264,000	$ 242,135,000
PENSION BENEFITS
Defined Benefit Plan Disclosure [Line Items]
Consecutive calendar years					5 years
Most recent period of employment					10 years
Estimated pension contributions required through 2022					$ 95,500,000
Discount rate					4.35%	3.73%
Expected return on plan assets					5.86%	6.08%
Actual return on plan assets					(7.31%)	16.32%
OTHER BENEFITS
Defined Benefit Plan Disclosure [Line Items]
Discount rate					4.16%	3.47%
Assets set aside in a trust					$ 0
Assumed health care cost trend rates for next fiscal year					5.00%	5.00%
Ultimate health care trend rate					5.00%
Postretirement benefit obligations					$ 36,325,000	$ 39,142,000
SERP BENEFITS
Defined Benefit Plan Disclosure [Line Items]
Consecutive calendar years					5 years
Most recent period of employment					60 months
Discount rate	4.08%	4.60%			4.34%	3.70%		4.22%	3.47%	4.15%
Number of highest cash bonuses | bonus					5
Number of executive officers receiving enhanced benefits | executive_officer					4
Number of executive officers receiving accelerated vesting | executive_officer					2
Number of executive officers with capped benefits | executive_officer						2			3
Curtailment charge		$ (3,600,000)
Special/contractual termination benefits	$ (300,000)	$ (3,200,000)
CLECO POWER
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefit obligations					$ 182,721,000	$ 173,747,000
CLECO POWER | OTHER BENEFITS
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost					3,300,000	3,300,000	$ 3,500,000
Postretirement benefit obligations					31,694,000	34,033,000
CLECO POWER | SERP BENEFITS
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost					1,400,000	1,300,000	$ 1,400,000
PREDECESSOR | PENSION BENEFITS
Defined Benefit Plan Disclosure [Line Items]
Discount rate		4.62%
Expected net periodic benefit cost, pension plan		$ 15,900,000
Net periodic benefit cost		$ 4,771,000
Expected return on plan assets		6.21%
PREDECESSOR | OTHER BENEFITS
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost		$ 1,122,000
PREDECESSOR | SERP BENEFITS
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost		9,017,000
Curtailment charge		(3,602,000)
Special/contractual termination benefits		(3,222,000)
PREDECESSOR | Support Group | PENSION BENEFITS
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost		$ 500,000
SUCCESSOR | PENSION BENEFITS
Defined Benefit Plan Disclosure [Line Items]
Discount rate										4.21%
Expected net periodic benefit cost, pension plan			$ 17,500,000
Net periodic benefit cost			$ 12,774,000		18,835,000	16,560,000
Expected return on plan assets			6.21%
SUCCESSOR | OTHER BENEFITS
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost			$ 2,349,000		2,920,000	2,965,000
SUCCESSOR | SERP BENEFITS
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost			4,447,000		6,372,000	5,963,000
Curtailment charge			0		0	0
Special/contractual termination benefits			0		0	(315,000)
SUCCESSOR | Support Group | PENSION BENEFITS
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost			$ 1,300,000		$ 2,000,000	$ 1,800,000
Scenario, Forecast | PENSION BENEFITS
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets				6.55%
Decrease in expected pension costs				$ 7,200,000