Investments in Unconsolidated Affiliates (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended			3 Months Ended		3 Months Ended			12 Months Ended			8 Months Ended	12 Months Ended		3 Months Ended				12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2010 Webb/Duval Gatherers ("Webb Duval")	Dec. 31, 2012 Webb/Duval Gatherers ("Webb Duval")	Dec. 31, 2012 Fort Union Gas Gathering	Mar. 31, 2012 Fort Union Gas Gathering	Sep. 30, 2011 Fort Union Gas Gathering	Dec. 31, 2012 Fort Union Gas Gathering	Dec. 31, 2011 Fort Union Gas Gathering	Dec. 31, 2010 Fort Union Gas Gathering	Dec. 31, 2010 Eagle Ford Gathering LLC ("Eagle Ford Gathering")	Dec. 31, 2012 Eagle Ford Gathering LLC ("Eagle Ford Gathering")	Dec. 31, 2011 Eagle Ford Gathering LLC ("Eagle Ford Gathering")	Dec. 31, 2012 Bighorn Gas Gathering, L.L.C. ("Bighorn")	Mar. 31, 2012 Bighorn Gas Gathering, L.L.C. ("Bighorn")	Sep. 30, 2011 Bighorn Gas Gathering, L.L.C. ("Bighorn")	Jun. 30, 2010 Bighorn Gas Gathering, L.L.C. ("Bighorn")	Dec. 31, 2012 Bighorn Gas Gathering, L.L.C. ("Bighorn")	Dec. 31, 2011 Bighorn Gas Gathering, L.L.C. ("Bighorn")	Dec. 31, 2010 Bighorn Gas Gathering, L.L.C. ("Bighorn")	Dec. 31, 2012 Investments in other unconsolidated affiliates	Dec. 31, 2011 Investments in other unconsolidated affiliates	Dec. 31, 2010 Investments in other unconsolidated affiliates
Investments in Unconsolidated Affiliates
Minimum ratio of net operating cash flow to debt service									1.25
Non-cash impairment charge on Investments in Unconsolidated Affiliates				$ 697		$ 18,000	$ 5,000	$ 45,000							$ 48,254	$ 115,000	$ 120,000	$ 25,000
Investment						145,588			145,588	169,856			155,224	120,910	43,902				43,902	212,071		86,733	41,894
Maximum percentage of contributed capital entitled to priority distribution from non-consent capital project																			140.00%
Summarized financial information for significant equity investments
Operating revenue									60,721	58,789	58,611		415,923	69,976					23,057	26,962	31,435	22,594	27,061	30,262
Operating expenses									(7,140)	(7,100)	(7,474)	(98)	(333,131)	(43,684)					(9,788)	(9,724)	(11,552)	(15,823)	(22,554)	(25,690)
Depreciation and amortization									(8,115)	(7,991)	(7,739)		(12,496)	(3,802)					(5,411)	(5,176)	(5,320)	(4,064)	(2,367)	(4,654)
Interest income (expense) and other									(1,517)	(2,040)	(3,915)		(828)	(275)					88	78	95
Other (expense) income, net																						(24)	(1)	7
Net income (loss)									43,949	41,658	39,483	(98)	69,468	22,215					7,946	12,140	14,658	2,683	2,139	(75)
Ownership %					62.50%	37.04%			37.04%	37.04%	37.04%	50.00%	50.00%	50.00%	51.00%				51.00%	51.00%	51.00%
Net income (loss) attributable to Copano									16,279	15,430	14,625	(49)	34,734	11,108					4,052	6,191	7,476
Priority allocation of earnings and other																			527	596	485
Copano's share of management fees charged									96	91	89	41	266	137					197	197	283
Amortization of the difference between the carried investment and the underlying equity in net assets									(27,545)	(50,990)	(6,423)		(82)	(27)					(166,532)	(130,107)	(36,715)
Equity in earnings (loss) from unconsolidated affiliates	(137,088)	(145,324)	(20,480)						(11,170)	(35,469)	8,291	(8)	34,918	11,218					(161,756)	(123,123)	(28,471)	920	2,050	(292)
Distributions									13,001	13,075	11,668		24,958	9,457					8,198	10,091	11,190	1,317	2,848	3,097
Contributions	72,313	121,967	33,002								774	29,982	24,619	88,789					1,982	1,444	848	45,712	31,734	750
Current assets						14,114			14,114	14,757	15,729	8,302	65,702	19,700	3,332				3,332	3,562	5,449	4,716	3,654	3,864
Noncurrent assets						187,988			187,988	196,184	204,424	57,956	265,360	238,877	84,269				84,269	87,847	88,754	170,968	75,002	17,405
Current liabilities						(60,744)			(60,744)	(19,359)	(19,944)	(6,392)	(27,193)	(23,627)	(1,178)				(1,178)	(1,943)	(1,031)	(15,984)	(4,163)	(4,951)
Noncurrent liabilities						(145)			(145)	(59,218)	(74,203)		(442)	(313)	(339)				(339)	(309)	(269)	(188)	(173)	(63)
Net assets						$ 141,213			$ 141,213	$ 132,364	$ 126,006	$ 59,866	$ 303,427	$ 234,637	$ 86,084				$ 86,084	$ 89,157	$ 92,903	$ 159,512	$ 74,320	$ 16,255