Fair Value Accounting - Fair Value of Financial Assets and Liabilities Measured On A Recurring Basis (Details) - Measured On A Recurring Basis - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Asset description
Institutional money market funds	$ 352,549	$ 129,643
Total assets	354,541	136,666
Liability description
Total liabilities	13,177	6,417
FTRs
Asset description
FTRs and other commodity derivatives	1,779	6,822
Liability description
FTRs and other commodity derivatives	683	1,044
Other commodity derivatives
Asset description
FTRs and other commodity derivatives	213	201
Liability description
FTRs and other commodity derivatives	12,494	5,373
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
QUOTED PRICES IN ACTIVE MARKETS FOR IDENTICAL ASSETS (LEVEL 1) | FTRs
Asset description
FTRs and other commodity derivatives	0	0
Liability description
FTRs and other commodity derivatives	0	0
QUOTED PRICES IN ACTIVE MARKETS FOR IDENTICAL ASSETS (LEVEL 1) | Other commodity derivatives
Asset description
FTRs and other commodity derivatives	0	0
Liability description
FTRs and other commodity derivatives	0	0
SIGNIFICANT OTHER OBSERVABLE INPUTS (LEVEL 2)
Asset description
Institutional money market funds	352,549	129,643
Total assets	352,762	129,844
Liability description
Total liabilities	12,494	5,373
SIGNIFICANT OTHER OBSERVABLE INPUTS (LEVEL 2) | FTRs
Asset description
FTRs and other commodity derivatives	0	0
Liability description
FTRs and other commodity derivatives	0	0
SIGNIFICANT OTHER OBSERVABLE INPUTS (LEVEL 2) | Other commodity derivatives
Asset description
FTRs and other commodity derivatives	213	201
Liability description
FTRs and other commodity derivatives	12,494	5,373
SIGNIFICANT UNOBSERVABLE INPUTS (LEVEL 3)
Asset description
Institutional money market funds	0	0
FTRs and other commodity derivatives	1,779	6,822
Total assets	1,779	6,822
Liability description
FTRs and other commodity derivatives	683	1,044
Total liabilities	683	1,044
SIGNIFICANT UNOBSERVABLE INPUTS (LEVEL 3) | FTRs
Asset description
FTRs and other commodity derivatives	1,779	6,822
Liability description
FTRs and other commodity derivatives	683	1,044
SIGNIFICANT UNOBSERVABLE INPUTS (LEVEL 3) | Other commodity derivatives
Asset description
FTRs and other commodity derivatives	0	0
Liability description
FTRs and other commodity derivatives	0	0
CLECO POWER
Asset description
Institutional money market funds	198,006	74,903
FTRs and other commodity derivatives	1,673	6,311
Total assets	199,679	81,214
Liability description
FTRs and other commodity derivatives	524	586
Total liabilities	524	586
CLECO POWER | QUOTED PRICES IN ACTIVE MARKETS FOR IDENTICAL ASSETS (LEVEL 1)
Asset description
Institutional money market funds	0	0
FTRs and other commodity derivatives	0	0
Total assets	0	0
Liability description
FTRs and other commodity derivatives	0	0
Total liabilities	0	0
CLECO POWER | SIGNIFICANT OTHER OBSERVABLE INPUTS (LEVEL 2)
Asset description
Institutional money market funds	198,006	74,903
FTRs and other commodity derivatives	0	0
Total assets	198,006	74,903
Liability description
FTRs and other commodity derivatives	0	0
Total liabilities	0	0
CLECO POWER | SIGNIFICANT UNOBSERVABLE INPUTS (LEVEL 3)
Asset description
Institutional money market funds	0	0
FTRs and other commodity derivatives	1,673	6,311
Total assets	1,673	6,311
Liability description
FTRs and other commodity derivatives	524	586
Total liabilities	$ 524	$ 586