Summary of Significant Accounting Policies (Details) (USD $)	3 Months Ended		6 Months Ended					6 Months Ended						3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended		12 Months Ended	3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended	9 Months Ended	12 Months Ended			3 Months Ended		9 Months Ended	12 Months Ended			3 Months Ended		6 Months Ended	9 Months Ended	12 Months Ended			3 Months Ended		9 Months Ended	12 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Jan. 28, 2011	Dec. 31, 2010	Jun. 30, 2011 Diversified Lands Mitigation Escrow Agreement [Member]	Jun. 30, 2011 GO Zone Project Costs [Member]	Jun. 30, 2011 Future Storm Restoration Costs [Member]	Jun. 30, 2011 Katrina/Rita Bond Payments [Member]	Jun. 30, 2011 Renewable Energy Grant [Member]	Jun. 30, 2011 Derivatives Not Designated As Hedging Instruments [Member] Fuel Cost Hedges [Member]	Dec. 31, 2010 Derivatives Not Designated As Hedging Instruments [Member] Fuel Cost Hedges [Member]	Jun. 30, 2010 Derivatives Not Designated As Hedging Instruments [Member] Economic Hedges [Member] Other Operations Revenue [Member]	Jun. 30, 2010 Derivatives Not Designated As Hedging Instruments [Member] Economic Hedges [Member] Other Operations Revenue [Member]	Jun. 30, 2010 Swap [Member]	Jun. 30, 2011 Swap [Member]	Jun. 30, 2010 Swap [Member]	Dec. 31, 2010 Swap [Member]	Jun. 30, 2011 Cleco Power [Member]	Jun. 30, 2010 Cleco Power [Member]	Jun. 30, 2011 Cleco Power [Member]	Jun. 30, 2010 Cleco Power [Member]	Dec. 31, 2010 Cleco Power [Member]	Mar. 31, 2011 Cleco Power [Member] Cash Flows Related To Accruals for Property, Plant and Equipment [Member] As Reported [Member]	Mar. 31, 2010 Cleco Power [Member] Cash Flows Related To Accruals for Property, Plant and Equipment [Member] As Reported [Member]	Jun. 30, 2010 Cleco Power [Member] Cash Flows Related To Accruals for Property, Plant and Equipment [Member] As Reported [Member]	Sep. 30, 2010 Cleco Power [Member] Cash Flows Related To Accruals for Property, Plant and Equipment [Member] As Reported [Member]	Dec. 31, 2010 Cleco Power [Member] Cash Flows Related To Accruals for Property, Plant and Equipment [Member] As Reported [Member]	Dec. 31, 2009 Cleco Power [Member] Cash Flows Related To Accruals for Property, Plant and Equipment [Member] As Reported [Member]	Dec. 31, 2008 Cleco Power [Member] Cash Flows Related To Accruals for Property, Plant and Equipment [Member] As Reported [Member]	Mar. 31, 2011 Cleco Power [Member] Cash Flows Related To Accruals for Property, Plant and Equipment [Member] As Adjusted [Member]	Mar. 31, 2010 Cleco Power [Member] Cash Flows Related To Accruals for Property, Plant and Equipment [Member] As Adjusted [Member]	Sep. 30, 2010 Cleco Power [Member] Cash Flows Related To Accruals for Property, Plant and Equipment [Member] As Adjusted [Member]	Dec. 31, 2010 Cleco Power [Member] Cash Flows Related To Accruals for Property, Plant and Equipment [Member] As Adjusted [Member]	Dec. 31, 2009 Cleco Power [Member] Cash Flows Related To Accruals for Property, Plant and Equipment [Member] As Adjusted [Member]	Dec. 31, 2008 Cleco Power [Member] Cash Flows Related To Accruals for Property, Plant and Equipment [Member] As Adjusted [Member]	Mar. 31, 2011 Cash Flows Related To Accruals for Property, Plant and Equipment [Member] As Reported [Member]	Mar. 31, 2010 Cash Flows Related To Accruals for Property, Plant and Equipment [Member] As Reported [Member]	Jun. 30, 2010 Cash Flows Related To Accruals for Property, Plant and Equipment [Member] As Reported [Member]	Sep. 30, 2010 Cash Flows Related To Accruals for Property, Plant and Equipment [Member] As Reported [Member]	Dec. 31, 2010 Cash Flows Related To Accruals for Property, Plant and Equipment [Member] As Reported [Member]	Dec. 31, 2009 Cash Flows Related To Accruals for Property, Plant and Equipment [Member] As Reported [Member]	Dec. 31, 2008 Cash Flows Related To Accruals for Property, Plant and Equipment [Member] As Reported [Member]	Mar. 31, 2011 Cash Flows Related To Accruals for Property, Plant and Equipment [Member] As Adjusted [Member]	Mar. 31, 2010 Cash Flows Related To Accruals for Property, Plant and Equipment [Member] As Adjusted [Member]	Sep. 30, 2010 Cash Flows Related To Accruals for Property, Plant and Equipment [Member] As Adjusted [Member]	Dec. 31, 2010 Cash Flows Related To Accruals for Property, Plant and Equipment [Member] As Adjusted [Member]	Dec. 31, 2009 Cash Flows Related To Accruals for Property, Plant and Equipment [Member] As Adjusted [Member]	Dec. 31, 2008 Cash Flows Related To Accruals for Property, Plant and Equipment [Member] As Adjusted [Member]
Property, Plant and Equipment [Abstract]
Regulated utility plants	$ 3,582,201,000		$ 3,582,201,000			$ 3,552,054,000
Other	257,010,000		257,010,000			258,842,000
Total property, plant and equipment	3,839,211,000		3,839,211,000			3,810,896,000														3,582,201,000		3,582,201,000		3,552,779,000
Accumulated depreciation	(1,198,373,000)		(1,198,373,000)			(1,162,456,000)														(1,122,387,000)		(1,122,387,000)		(1,085,945,000)
Net property, plant and equipment	2,640,838,000		2,640,838,000			2,648,440,000														2,459,814,000		2,459,814,000		2,466,834,000
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	35,200,000		35,200,000			41,000,000	100,000		26,400,000	8,100,000	600,000
Decrease in restricted cash (the amount used during the period)			5,849,000	37,654,000				6,100,000														5,849,000	7,522,000
Decrease in restricted cash due to bond principal payment										6,300,000
Decrease in restricted cash due to bond interest payment										3,800,000
Increase in restricted cash due to collections									400,000	9,400,000	600,000
Risk Management [Abstract]
Realized gains (losses)														(300,000)	(500,000)
Mark-to-market gains (losses)														400,000	0
Unrealized gains (losses)												(7,700,000)	(15,100,000)
Deferred gains (losses)												(2,100,000)	(1,600,000)
Net collateral deposited	1,800,000		1,800,000			4,300,000
Interest rate cash flow hedge [Abstract]
Amount of hedged item																	50,000,000
Description of hedged item																	bank loan with variable interest, paid monthly, and calculated at 3.00% plus the one-month LIBOR
Underlying risk																	risk of future floating interest rates
Fixed interest rate (in hundredths)																	1.84%
Gain (loss) on discontinuation of interest rate cash flow hedge																			(1,100,000)
Reclassification adjustments of interest rate cash flow hedge																200,000		400,000
Reclassifications [Abstract]
Accounts receivable			(19,923,000)	(19,498,000)																		(20,779,000)	(20,812,000)		8,280,000	(20,597,000)	(20,812,000)	(50,579,000)	(35,261,000)	9,646,000	(5,972,000)	(10,720,000)	(20,597,000)	(31,579,000)	(16,261,000)	9,646,000	(5,972,000)	5,042,000	(17,889,000)	(19,498,000)	(49,329,000)	(35,156,000)	8,310,000	(5,557,000)	(13,958,000)	(17,889,000)	(30,329,000)	(16,156,000)	8,310,000	(5,557,000)
Accounts payable			(7,575,000)	(25,684,000)																		(6,703,000)	(21,494,000)		(31,202,000)	(43,863,000)	(27,280,000)	(16,621,000)	3,936,000	10,831,000	942,000	(34,966,000)	(46,245,000)	(12,137,000)	8,934,000	18,254,000	(8,197,000)	(31,823,000)	(50,499,000)	(31,420,000)	(17,248,000)	3,459,000	11,231,000	2,806,000	(35,617,000)	(53,362,000)	(13,277,000)	8,167,000	18,593,000	(6,334,000)
Retainage payable			(430,000)	0																		(430,000)	0		1,004,000	(862,000)	195,000	745,000	1,913,000	(11,921,000)	12,709,000	(13,000)			(27,000)	(13,011,000)	(60,000)	1,004,000	(862,000)	195,000	745,000	1,913,000	(11,921,000)	12,709,000	(13,000)			(27,000)	(13,011,000)	(60,000)
Net cash provided by operating activities			147,830,000	107,978,000																		70,788,000	34,932,000		29,081,000	(12,130,000)	29,341,000	76,949,000	148,701,000	141,726,000	62,078,000	5,299,000	(13,650,000)	99,688,000	170,759,000	148,059,000	40,170,000	26,111,000	60,792,000	102,437,000	170,141,000	193,405,000	135,179,000	89,526,000	2,302,000	58,791,000	192,368,000	215,173,000	141,452,000	67,618,000
Additions to property, plant and equipment			(66,081,000)	(217,660,000)																		(58,453,000)	(63,781,000)		(44,501,000)	(30,257,000)	(58,190,000)	(75,660,000)	(127,153,000)	(249,252,000)	(334,652,000)	(20,720,000)	(28,737,000)	(98,399,000)	(149,211,000)	(255,585,000)	(312,744,000)	(45,692,000)	(183,561,000)	(212,119,000)	(230,485,000)	(283,389,000)	(250,286,000)	(335,757,000)	(21,883,000)	(181,560,000)	(252,711,000)	(305,157,000)	(256,558,000)	(313,848,000)
Net cash used in investing activities			18,249,000	(196,904,000)																		(48,590,000)	(46,387,000)		(32,737,000)	(12,126,000)	(40,796,000)	(49,780,000)	(112,614,000)	(141,998,000)	(353,248,000)	(8,955,000)	(10,606,000)	(72,519,000)	(134,672,000)	(148,331,000)	(331,340,000)	(43,346,000)	(149,609,000)	(191,363,000)	(212,592,000)	(285,137,000)	(177,176,000)	(368,725,000)	(19,537,000)	(147,608,000)	(234,819,000)	(306,905,000)	(183,449,000)	(346,817,000)
Net decrease in cash and cash equivalents			(29,002,000)	(93,038,000)																		(35,071,000)	(93,339,000)		(60,472,000)	(55,625,000)	(93,339,000)	(110,729,000)	46,799,000	46,571,000	79,598,000	(60,472,000)	(55,625,000)	(110,729,000)	46,799,000	46,571,000	79,598,000	(53,937,000)	(52,971,000)	(93,038,000)	(77,357,000)	45,935,000	47,710,000	(31,530,000)	(53,937,000)	(52,971,000)	(77,357,000)	45,935,000	47,710,000	(31,530,000)
Cash and cash equivalents at beginning of period			191,128,000	145,193,000																		184,912,000	138,113,000		184,912,000	138,113,000	138,113,000	138,113,000	138,113,000	91,542,000	11,944,000	184,912,000	138,113,000	138,113,000	138,113,000	91,542,000	11,944,000	191,128,000	145,193,000	145,193,000	145,193,000	145,193,000	97,483,000	129,013,000	191,128,000	145,193,000	145,193,000	145,193,000	97,483,000	129,013,000
Cash and cash equivalents at end of period	162,126,000	52,155,000	162,126,000	52,155,000																149,841,000	44,774,000	149,841,000	44,774,000		124,440,000	82,488,000	44,774,000	27,384,000	184,912,000	138,113,000	91,542,000	124,440,000	82,488,000	27,384,000	184,912,000	138,113,000	91,542,000	137,191,000	92,222,000	52,155,000	67,836,000	191,128,000	145,193,000	97,483,000	137,191,000	92,222,000	67,836,000	191,128,000	145,193,000	97,483,000
Accrued additions to property, plant and equipment			14,548,000	7,232,000																		20,281,000	7,137,000		17,233,000	4,039,000	2,738,000	17,506,000	17,765,000	3,069,000	16,935,000	23,246,000	9,742,000	4,757,000	5,697,000	11,335,000	36,074,000	17,155,000	4,039,000	2,738,000	17,506,000	17,765,000	3,069,000	16,935,000	23,245,000	10,268,000	5,314,000	6,032,000	11,396,000	36,074,000
Calculation of basic and diluted earnings per share [Abstract]
Income from continuing operations	70,348,000	35,186,000	99,363,000	185,155,000																35,694,000	39,089,000	65,724,000	71,249,000
Deduct: non-participating stock dividends (4.5% preferred stock)	15,000	12,000	26,000	23,000
Deduct: non-participating stock redemption costs (4.5% preferred stock)	112,000	0	112,000	0
Basic net income applicable to common stock	70,221,000	35,174,000	99,225,000	185,132,000
Shares [Abstract]
Average number of basic common shares outstanding (in shares)	60,655,538	60,431,930	60,613,371	60,374,233
Effect of dilutive securities
Add: stock option grants (in shares)	21,634	28,742	21,067	29,713
Add: restricted stock (LTICP) (in shares)	346,267	244,597	163,107	115,120
Average number of diluted common shares outstanding (in shares)	61,023,439	60,705,269	60,797,545	60,519,066
Per Share Amount [Abstract]
Basic net income applicable to common stock (in dollars per share)	$ 1.16	$ 0.58	$ 1.64	$ 3.07
Diluted net income applicable to common stock (in dollars per share)	$ 1.15	$ 0.58	$ 1.63	$ 3.06
Preferred Stock Redemption [Abstract]
Outstanding shares of preferred stock (in shares)	0		0			10,288
Dividend rate (in hundredths)			4.50%
Redemption date			Jun. 24, 2011
Redemption price (in dollars per share)	$ 101		$ 101
Redemption price, plus accrued and unpaid dividends to the redemption date (in dollars per share)	$ 101.296		$ 101.296
Stock-Based Compensation [Abstract]
Non-vested stock granted (in shares)					145,002
Equity classification
Non-vested stock	796,000	468,000	1,947,000	1,130,000																201,000	98,000	522,000	268,000
Stock options	23,000	13,000	36,000	25,000
Total equity classification	819,000	481,000	1,983,000	1,155,000																201,000	98,000	522,000	268,000
Liability classification
Common stock equivalent units	364,000	481,000	1,559,000	630,000																154,000	174,000	586,000	348,000
Total pre-tax compensation expense	1,183,000	962,000	3,542,000	1,785,000																355,000	272,000	1,108,000	616,000
Tax benefit (excluding income tax gross-up)	$ 455,000	$ 370,000	$ 1,363,000	$ 687,000																$ 137,000	$ 105,000	$ 426,000	$ 237,000