Pension Plan and Employee Benefits, Pension Plan and Other Benefits Plan (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
PENSION BENEFITS
Components of periodic benefit costs
Service cost	$ 2,393	$ 2,225
Interest cost	5,183	5,358
Expected return on plan assets	(5,938)	(6,138)
Prior period service credit	(18)	(18)
Net loss (gain)	2,960	2,413
Net periodic benefit cost	4,580	3,840
OTHER BENEFITS
Components of periodic benefit costs
Service cost	338	385
Interest cost	357	403
Expected return on plan assets	0	0
Prior period service credit	0	0
Net loss (gain)	5	(3)
Net periodic benefit cost	700	785
Cleco Power | OTHER BENEFITS
Components of periodic benefit costs
Net periodic benefit cost	$ 800	$ 900