Pension Plan and Employee Benefits - Narrative (Details) - USD ($)	1 Months Ended	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Mar. 30, 2017	Mar. 29, 2017
PENSION BENEFITS
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost		$ 4,837,000	$ 4,440,000	$ 9,417,000	$ 8,280,000
OTHER BENEFITS
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost		700,000	785,000	1,400,000	1,570,000
Assets held-in-trust, noncurrent		0		0
SERP Benefits
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost		1,770,000	1,517,000	3,186,000	3,139,000
Defined benefit plan, assumptions used calculating benefit obligation, discount rate						4.08%	4.22%
Defined benefit plan, net periodic benefit cost (credit), gain (loss) due to settlement	$ (300,000)	0	0	0	(315,000)
CLECO POWER | OTHER BENEFITS
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost		800,000	900,000	1,600,000	1,700,000
CLECO POWER | SERP Benefits
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost		400,000	300,000	700,000	600,000
Other Subsidiaries | PENSION BENEFITS
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost		$ 500,000	$ 500,000	$ 1,000,000	$ 900,000