Fair Value Accounting, Fair Value Measurements and Disclosures(Details)	3 Months Ended
	Mar. 31, 2018 USD ($) $ / MW	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($) $ / MW
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
FTR forward price - per MWh, low | $ / MW	(7.21)		(2.95)
FTR forward price - per MWh, high | $ / MW	7.21		6.33
Fair value, concentration of risk, amount of money market funds in cash and cash equivalents	$ 172,500,000		$ 111,100,000
Fair value, assets and liabilities, transfers between levels, amount	0		0
Restricted Cash and Cash Equivalents, Current
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Fair value, concentration of risk, amount of money market funds in institutional money market funds	6,700,000		13,100,000
Restricted Cash and Cash Equivalents, Noncurrent
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Fair value, concentration of risk, amount of money market funds in institutional money market funds	19,200,000		20,100,000
Measured On A Recurring Basis
Asset description
Institutional money market funds	198,446,000		144,302,000
FTRs	4,828,000		7,396,000
Total assets	203,274,000		151,698,000
Liability description
FTRs	545,000		352,000
Total liabilities	545,000		352,000
Price Risk Derivative
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	7,044,000	$ 7,683,000
Unrealized gains	1,617,000	2,104,000
Purchases	371,000	275,000
Settlements	(4,749,000)	(5,644,000)
Ending balance	4,283,000	$ 4,418,000
QUOTED PRICES IN ACTIVE MARKETS FOR IDENTICAL ASSETS (LEVEL 1) | Measured On A Recurring Basis
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) | Measured On A Recurring Basis
Asset description
Institutional money market funds	198,446,000		144,302,000
FTRs	0		0
Total assets	198,446,000		144,302,000
Liability description
FTRs	0		0
Total liabilities	0		0
SIGNIFICANT UNOBSERVABLE INPUTS (LEVEL 3) | Measured On A Recurring Basis
Asset description
Institutional money market funds	0		0
FTRs	4,828,000		7,396,000
Total assets	4,828,000		7,396,000
Liability description
FTRs	545,000		352,000
Total liabilities	545,000		352,000
Cleco Power
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Fair value, concentration of risk, amount of money market funds in cash and cash equivalents	125,300,000		62,500,000
Cleco Power | Restricted Cash and Cash Equivalents, Current
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Fair value, concentration of risk, amount of money market funds in institutional money market funds	6,700,000		13,100,000
Cleco Power | Restricted Cash and Cash Equivalents, Noncurrent
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Fair value, concentration of risk, amount of money market funds in institutional money market funds	19,200,000		20,100,000
Cleco Power | Measured On A Recurring Basis
Asset description
Institutional money market funds	151,225,000		95,681,000
FTRs	4,828,000		7,396,000
Total assets	156,053,000		103,077,000
Liability description
FTRs	545,000		352,000
Total liabilities	545,000		352,000
Cleco Power | QUOTED PRICES IN ACTIVE MARKETS FOR IDENTICAL ASSETS (LEVEL 1) | Measured On A Recurring Basis
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) | Measured On A Recurring Basis
Asset description
Institutional money market funds	151,225,000		95,681,000
FTRs	0		0
Total assets	151,225,000		95,681,000
Liability description
FTRs	0		0
Total liabilities	0		0
Cleco Power | SIGNIFICANT UNOBSERVABLE INPUTS (LEVEL 3) | Measured On A Recurring Basis
Asset description
Institutional money market funds	0		0
FTRs	4,828,000		7,396,000
Total assets	4,828,000		7,396,000
Liability description
FTRs	545,000		352,000
Total liabilities	$ 545,000		$ 352,000