Pension Plan and Employee Benefits - Narrative (Details) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Discretionary contribution	$ 12,300,000
Pension contributions required through 2024						$ 66,500,000
Defined benefit plan contributions by employer		$ 5,473,000	$ 3,044,000	$ 16,423,000	$ 9,132,000
Pension Plan | Other Subsidiaries
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan contributions by employer		900,000	500,000	2,600,000	1,600,000
Pension Plan | Minimum
Defined Benefit Plan Disclosure [Line Items]
Expected contributions in 2020						$ 15,700,000
Other Benefits Plan
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan contributions by employer		1,380,000	868,000	3,895,000	2,156,000
Assets held-in-trust, noncurrent		0		0
Other Benefits Plan | CLECO POWER
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan contributions by employer		1,100,000	900,000	3,600,000	2,300,000
SERP
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan contributions by employer		1,575,000	1,260,000	4,726,000	3,780,000
SERP | CLECO POWER
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan contributions by employer		$ 200,000	$ 200,000	$ 700,000	$ 600,000