Related Party Transaction (Details) (USD $)	3 Months Ended				6 Months Ended
	Jun. 30, 2011		Jun. 30, 2010		Jun. 30, 2011		Jun. 30, 2010
Summary of transactions between CPNO and affiliates
Natural gas sales	$ 123,928,000		$ 84,819,000		$ 227,723,000		$ 205,035,000
Compressor rental fees	13,472,000		13,914,000		26,130,000		27,932,000
Gathering and compression services	27,898,000		16,516,000		52,369,000		29,630,000
Natural gas purchases	274,398,000	[1]	167,613,000	[1]	498,128,000	[1]	377,478,000	[1]
Reimbursable costs	105,000
Transportation	6,362,000	[1]	5,603,000	[1]	12,211,000	[1]	11,279,000	[1]
Related Party Transactions (Textuals) [Abstract]
Purchase of vessel from Copano Operations	102,000
Affiliates of Mr. Lawing [Member]
Summary of transactions between CPNO and affiliates
Natural gas sales			1,000		(1,000)		2,000
Gathering and compression services	1,000		2,000		3,000		5,000
Natural gas purchases	22,000		108,000		82,000		389,000
Reimbursable costs	57,000		75,000		114,000		150,000
Webb Duval [Member]
Summary of transactions between CPNO and affiliates
Natural gas sales	39,000		12,000		39,000		12,000
Natural gas purchases	(308,000)		59,000		(369,000)		112,000
Management fees	56,000		56,000		112,000		112,000
Reimbursable costs	224,000		72,000		337,000		139,000
Transportation	119,000		61,000		170,000		131,000
Payable to us as of June 30, 2011	275,000				275,000
Payable by us as of June 30, 2011	45,000				45,000
Eagle Ford Gathering [Member]
Summary of transactions between CPNO and affiliates
Management fees	41,000				82,000
Reimbursable costs	3,482,000				13,595,000
Capital project fees	260,000				548,000
Payable to us as of June 30, 2011	22,000				22,000
Payable by us as of June 30, 2011	57,000				57,000
Liberty Pipeline Group [Member]
Summary of transactions between CPNO and affiliates
Reimbursable costs	12,011,000				15,505,000
Payable to us as of June 30, 2011	30,000				30,000
Southern Dome [Member]
Summary of transactions between CPNO and affiliates
Management fees	62,000		63,000		125,000		125,000
Reimbursable costs			61,000		201,000		157,000
Payable to us as of June 30, 2011	52,000				52,000
Bighorn [Member]
Summary of transactions between CPNO and affiliates
Compressor rental fees	398,000		417,000		815,000		833,000
Natural gas purchases							3,000
Management fees	97,000		139,000		193,000		278,000
Reimbursable costs	579,000		563,000		1,162,000		1,225,000
Transportation							16,000
Payable to us as of June 30, 2011	245,000				245,000
Other [Member]
Summary of transactions between CPNO and affiliates
Natural gas sales			65,000				125,000
Payable to us as of June 30, 2011	6,000				6,000
Affiliate of TPG [Member]
Related Party Transactions (Textuals) [Abstract]
Amount paid for purchase and installation of compressor, compression services , repairs	21,000				55,000
Exterran Holdings [Member]
Related Party Transactions (Textuals) [Abstract]
Amount paid for purchase and installation of compressor, compression services , repairs	1,380,000		3,132,000		2,031,000		4,120,000
Fort Union [Member]
Summary of transactions between CPNO and affiliates
Natural gas purchases					6,000		52,000
Management fees	61,000		60,000		123,000		120,000
Reimbursable costs	59,000		50,000		776,000		129,000
Transportation	1,379,000		1,267,000		2,659,000		2,638,000
Payable to us as of June 30, 2011	$ 16,000				$ 16,000

[1] Exclusive of operations and maintenance and depreciation and amortization shown separately below.