Pension Plan and Employee Benefits - SERP (Details) - SERP Benefits - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Components of periodic benefit costs
Service cost		$ 166	$ 102	$ 271	$ 247
Interest cost		1,004	820	1,764	1,620
Amortizations
Prior period service credit		(47)	(29)	(81)	(68)
Net loss (gain)		647	624	1,232	1,025
Net periodic benefit cost		1,770	1,517	3,186	2,824
Special/contractual termination benefits	$ 300	0	0	0	315
Net periodic benefit cost		1,770	1,517	3,186	3,139
CLECO POWER
Amortizations
Net periodic benefit cost		$ 400	$ 300	$ 700	$ 600