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Debt, Additional Disclosures (Details) - USD ($)			3 Months Ended	12 Months Ended
Debt, Additional Disclosures (Details) - USD ($)	Apr. 28, 2017	Mar. 01, 2017	Apr. 12, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Mar. 28, 2018	Dec. 18, 2017	May 31, 2016	Mar. 31, 2008
Debt [Line Items]
Short-term debt outstanding				$ 0	$ 0
Long-term Debt and Capital Lease Obligations, Including Current Maturities				2,860,000,000
Long-term Debt and Capital Lease Obligations, Current				19,193,000	19,715,000
Debt Instrument, Fee Amount				11,600,000	11,700,000
Cleco Holdings [Member]
Debt [Line Items]
Short-term debt outstanding				0	0
Long-term Debt and Capital Lease Obligations, Including Current Maturities				1,340,000,000
Long-term Debt and Capital Lease Obligations, Current				0
Debt Instrument, Fee Amount				2,516,000	2,261,000
Cleco Corporate Holdings debt, variable rate, due 2019 [Member] \| Cleco Holdings [Member]
Debt [Line Items]
Debt Instrument, Face Amount									$ 1,350,000,000
Cleco Holdings' senior notes, 3.743%, due 2026 [Member] \| Cleco Holdings [Member]
Debt [Line Items]
Unsecured Debt				535,000,000	535,000,000
Debt Instrument, Face Amount									$ 535,000,000
Debt Instrument, Interest Rate, Stated Percentage									3.743%
Debt Conversion, Original Debt, Interest Rate of Debt	3.743%
Debt Conversion, Converted Instrument, Rate	3.743%
Cleco Holdings' senior notes, 4.973%, due 2046 [Member] \| Cleco Holdings [Member]
Debt [Line Items]
Unsecured Debt				350,000,000	350,000,000
Debt Instrument, Face Amount									$ 350,000,000
Debt Instrument, Interest Rate, Stated Percentage									4.973%
Debt Conversion, Original Debt, Interest Rate of Debt	4.973%
Debt Conversion, Converted Instrument, Rate	4.973%
Cleco Holdings' senior notes, 3.250%, due 2023 [Member] \| Cleco Holdings [Member]
Debt [Line Items]
Unsecured Debt				165,000,000	165,000,000
Cleco Power [Member]
Debt [Line Items]
Short-term debt outstanding				0	0
Long-term Debt and Capital Lease Obligations, Including Current Maturities				1,360,000,000
Long-term Debt and Capital Lease Obligations, Current				19,193,000	19,715,000
Long-term Debt, Current Maturities				19,193,000	17,896,000
Capital Lease Obligations				0	1,819,000
Capital lease payments/Current liabilities				0	1,819,000
Unsecured Debt				1,375,819,000	1,268,715,000
Debt Instrument, Face Amount								$ 175,000,000
Debt Instrument, Fee Amount				9,141,000	9,421,000
Repayments of Long-term Debt				17,896,000	326,814,000	$ 100,824,000
Cleco Power [Member] \| Cleco Katrina Rita Storm Recovery Bonds [Member]
Debt [Line Items]
Debt Instrument, Face Amount										$ 180,600,000
Cleco Power [Member] \| Cleco Power's senior notes, 3.47%, due 2026 [Member]
Debt [Line Items]
Unsecured Debt				130,000,000	130,000,000
Cleco Power [Member] \| Cleco Power's senior notes, 3.57%, due 2028 [Member]
Debt [Line Items]
Unsecured Debt				200,000,000	200,000,000
Cleco Power [Member] \| 2008 Series A GO Zone bonds
Debt [Line Items]
Unsecured Debt				50,000,000	50,000,000
Cleco Power [Member] \| Cleco Power's senior notes, 3.68%, due 2025 [Member] [Member]
Debt [Line Items]
Unsecured Debt				$ 75,000,000	$ 75,000,000
Cleco Power [Member] \| Cleco Katrina Rita's storm recovery bonds, 4.41%, due 2020 [Member]
Debt [Line Items]
Debt Instrument, Face Amount										$ 113,000,000
Debt Instrument, Interest Rate, Stated Percentage										4.41%
Repayments of Long-term Debt		$ 1,100,000
Interest Paid		$ 100,000
Cleco Power [Member] \| Senior Notes, Series B, 3.08%, due 2023 [Member]
Debt [Line Items]
Debt Instrument, Face Amount								$ 100,000,000
Debt Instrument, Interest Rate, Stated Percentage								3.08%
Cleco Power [Member] \| Senior Notes, Series A, 2.94%, due 2022 [Member]
Debt [Line Items]
Debt Instrument, Face Amount								$ 25,000,000
Debt Instrument, Interest Rate, Stated Percentage								2.94%
Subsequent Event [Member] \| Cleco Power [Member] \| Senior Notes, Series C, 3.17%, due 2024 [Member]
Debt [Line Items]
Debt Instrument, Face Amount							$ 50,000,000
Debt Instrument, Interest Rate, Stated Percentage							3.17%
Predecessor [Member]
Debt [Line Items]
Repayments of Long-term Debt			$ 8,546,000			100,824,000
Predecessor [Member] \| Cleco Holdings [Member]
Debt [Line Items]
Repayments of Long-term Debt			$ 0			$ 0