Investments in Unconsolidated Affiliates (Details 1) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Summarized financial information for significant equity investments
Equity in loss (earnings) from unconsolidated affiliates	$ 1,306,000	$ (23,632,000)	$ 3,008,000	$ (21,837,000)
Distributions			12,323,000	10,993,000
Bighorn [Member]
Summarized financial information for significant equity investments
Operating revenue			13,903,000	15,973,000
Operating expenses			(4,589,000)	(5,961,000)
Depreciation and amortization			(2,587,000)	(2,549,000)
Interest income (expense) and other			42,000	22,000
Net income			6,769,000	7,485,000
Ownership Percentage	51.00%	51.00%	51.00%	51.00%
Copano's share, net income (loss)			3,452,000	3,817,000
Priority allocation of earnings and other			254,000	195,000
Copano's share of management fees charged			98,000	142,000
Amortization of difference between the carried investment and the underlying equity in net assets			(5,629,000)	(31,084,000)
Equity in loss (earnings) from unconsolidated affiliates			(1,825,000)	(26,930,000)
Distributions			4,956,000	5,497,000
Current assets	5,912,000	6,605,000	5,912,000	6,605,000
Noncurrent assets	86,667,000	90,891,000	86,667,000	90,891,000
Current liabilities	(1,084,000)	(1,238,000)	(1,084,000)	(1,238,000)
Noncurrent liabilities	(282,000)	(257,000)	(282,000)	(257,000)
Net assets	91,213,000	96,001,000	91,213,000	96,001,000
Fort Union Gas Gathering [Member]
Summarized financial information for significant equity investments
Operating revenue			27,104,000	28,009,000
Operating expenses			(3,455,000)	(3,926,000)
Depreciation and amortization			(3,996,000)	(3,629,000)
Interest income (expense) and other			(1,228,000)	(2,332,000)
Net income			18,425,000	18,122,000
Ownership Percentage	37.04%	37.04%	37.04%	37.04%
Copano's share, net income (loss)			6,825,000	6,712,000
Copano's share of management fees charged			46,000	44,000
Amortization of difference between the carried investment and the underlying equity in net assets			(3,212,000)	(3,212,000)
Equity in loss (earnings) from unconsolidated affiliates			3,659,000	3,544,000
Distributions			7,408,000	5,371,000
Current assets	9,721,000	14,437,000	9,721,000	14,437,000
Noncurrent assets	200,270,000	208,624,000	200,270,000	208,624,000
Current liabilities	(18,782,000)	(19,852,000)	(18,782,000)	(19,852,000)
Noncurrent liabilities	(66,779,000)	(81,565,000)	(66,779,000)	(81,565,000)
Net assets	$ 124,430,000	$ 121,644,000	$ 124,430,000	$ 121,644,000