Fair Value Accounting - Fair Value of Financial Assets and Liabilities Measured On A Recurring Basis (Details) - Measured On A Recurring Basis - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Asset Description
Institutional money market funds	$ 129,643	$ 133,722
Total assets	136,666	157,077
Liability Description
Total liabilities	6,417	468
QUOTED PRICES IN ACTIVE MARKETS FOR IDENTICAL ASSETS (LEVEL 1)
Asset Description
Institutional money market funds	0	0
Total assets	0	0
Liability Description
Total liabilities	0	0
SIGNIFICANT OTHER OBSERVABLE INPUTS (LEVEL 2)
Asset Description
Institutional money market funds	129,643	133,722
Total assets	129,844	133,722
Liability Description
Total liabilities	5,373	0
SIGNIFICANT UNOBSERVABLE INPUTS (LEVEL 3)
Asset Description
Institutional money market funds	0	0
Assets	6,822	23,355
Total assets	6,822	23,355
Liability Description
Liabilities	1,044	468
Total liabilities	1,044	468
CLECO POWER
Asset Description
Institutional money market funds	74,903	55,900
Total assets	81,214	79,255
Liability Description
Total liabilities	586	468
CLECO POWER | QUOTED PRICES IN ACTIVE MARKETS FOR IDENTICAL ASSETS (LEVEL 1)
Asset Description
Institutional money market funds	0	0
Total assets	0	0
Liability Description
Total liabilities	0	0
CLECO POWER | SIGNIFICANT OTHER OBSERVABLE INPUTS (LEVEL 2)
Asset Description
Institutional money market funds	74,903	55,900
Total assets	74,903	55,900
Liability Description
Total liabilities	0	0
CLECO POWER | SIGNIFICANT UNOBSERVABLE INPUTS (LEVEL 3)
Asset Description
Institutional money market funds	0	0
Assets	6,311	23,355
Total assets	6,311	23,355
Liability Description
Liabilities	586	468
Total liabilities	586	468
Financial Transmission Right
Asset Description
Assets	6,822	23,355
Liability Description
Liabilities	1,044	468
Financial Transmission Right | QUOTED PRICES IN ACTIVE MARKETS FOR IDENTICAL ASSETS (LEVEL 1)
Asset Description
Assets	0	0
Liability Description
Liabilities	0	0
Financial Transmission Right | SIGNIFICANT OTHER OBSERVABLE INPUTS (LEVEL 2)
Asset Description
Assets	0	0
Liability Description
Liabilities	0	0
Financial Transmission Right | SIGNIFICANT UNOBSERVABLE INPUTS (LEVEL 3)
Asset Description
Assets	6,822	23,355
Liability Description
Liabilities	1,044	468
Financial Transmission Right | CLECO POWER
Asset Description
Assets	6,311	23,355
Liability Description
Liabilities	586	468
Financial Transmission Right | CLECO POWER | QUOTED PRICES IN ACTIVE MARKETS FOR IDENTICAL ASSETS (LEVEL 1)
Asset Description
Assets	0	0
Liability Description
Liabilities	0	0
Financial Transmission Right | CLECO POWER | SIGNIFICANT OTHER OBSERVABLE INPUTS (LEVEL 2)
Asset Description
Assets	0	0
Liability Description
Liabilities	0	0
Financial Transmission Right | CLECO POWER | SIGNIFICANT UNOBSERVABLE INPUTS (LEVEL 3)
Asset Description
Assets	6,311	23,355
Liability Description
Liabilities	586	468
Other Commodity Derivatives
Asset Description
Assets	201	0
Liability Description
Liabilities	5,373	0
Other Commodity Derivatives | QUOTED PRICES IN ACTIVE MARKETS FOR IDENTICAL ASSETS (LEVEL 1)
Asset Description
Assets	0	0
Liability Description
Liabilities	0	0
Other Commodity Derivatives | SIGNIFICANT OTHER OBSERVABLE INPUTS (LEVEL 2)
Asset Description
Assets	201	0
Liability Description
Liabilities	5,373	0
Other Commodity Derivatives | SIGNIFICANT UNOBSERVABLE INPUTS (LEVEL 3)
Asset Description
Assets	0	0
Liability Description
Liabilities	$ 0	$ 0