Summary of Significant Accounting Policies - Recent Authoritative Guidance (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Apr. 12, 2016	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SUCCESSOR
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other operations and maintenance		$ 138,298	$ 197,038	$ 197,610
Other expense		10,003	15,843	13,373
PREDECESSOR
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other operations and maintenance	$ 59,929
Other expense	4,037
CLECO POWER
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other operations and maintenance			202,556	202,738	$ 203,452
Other expense			$ 11,441	10,407	10,505
Restatement Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other operations and maintenance				400	7,300
Restatement Adjustment | CLECO POWER
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other operations and maintenance				400	7,300
Restatement Adjustment | Accounting Standards Update 2017-07 | SUCCESSOR
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other operations and maintenance		(8,618)		(11,071)
Other expense		$ 8,618		11,071
Restatement Adjustment | Accounting Standards Update 2017-07 | PREDECESSOR
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other operations and maintenance	(3,447)
Other expense	$ 3,447
Restatement Adjustment | Accounting Standards Update 2017-07 | CLECO POWER
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other operations and maintenance				(7,612)	(8,529)
Other expense				$ 7,612	$ 8,529