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, 2018	Dec. 31, 2017
Asset Description
Institutional money market funds	$ 133,722	$ 144,302
FTRs	23,355	7,396
Total assets	157,077	151,698
Liability Description
FTRs	468	352
Total liabilities	468	352
QUOTED PRICES IN ACTIVE MARKETS FOR IDENTICAL ASSETS (LEVEL 1)
Asset Description
Institutional money market funds	0	0
FTRs	0	0
Total assets	0	0
Liability Description
FTRs	0	0
Total liabilities	0	0
SIGNIFICANT OTHER OBSERVABLE INPUTS (LEVEL 2)
Asset Description
Institutional money market funds	133,722	144,302
FTRs	0	0
Total assets	133,722	144,302
Liability Description
FTRs	0	0
Total liabilities	0	0
SIGNIFICANT UNOBSERVABLE INPUTS (LEVEL 3)
Asset Description
Institutional money market funds	0	0
FTRs	23,355	7,396
Total assets	23,355	7,396
Liability Description
FTRs	468	352
Total liabilities	468	352
CLECO POWER
Asset Description
Institutional money market funds	55,900	95,681
FTRs	23,355	7,396
Total assets	79,255	103,077
Liability Description
FTRs	468	352
Total liabilities	468	352
CLECO POWER | QUOTED PRICES IN ACTIVE MARKETS FOR IDENTICAL ASSETS (LEVEL 1)
Asset Description
Institutional money market funds	0	0
FTRs	0	0
Total assets	0	0
Liability Description
FTRs	0	0
Total liabilities	0	0
CLECO POWER | SIGNIFICANT OTHER OBSERVABLE INPUTS (LEVEL 2)
Asset Description
Institutional money market funds	55,900	95,681
FTRs	0	0
Total assets	55,900	95,681
Liability Description
FTRs	0	0
Total liabilities	0	0
CLECO POWER | SIGNIFICANT UNOBSERVABLE INPUTS (LEVEL 3)
Asset Description
Institutional money market funds	0	0
FTRs	23,355	7,396
Total assets	23,355	7,396
Liability Description
FTRs	468	352
Total liabilities	$ 468	$ 352