Long Term Debt (Details 1) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2010	Dec. 31, 2009
Current assets:
Cash and cash equivalents	$ 53,534	$ 59,930	$ 101,781	$ 44,692
Accounts receivable, net	108,339	96,662
Intercompany receivable	0	0
Risk management assets	12,101	7,836
Prepayments and other current assets	8,311	5,179
Total current assets	182,285	169,607
Property, plant and equipment, net	1,078,948	912,157
Intangible assets, net	179,992	188,585
Investments in unconsolidated affiliates	529,958	604,304
Investment in consolidated subsidiaries	0	0
Escrow cash	1,850	1,856
Risk management assets	17,128	11,943
Other assets, net	27,739	18,541
Total assets	2,017,900	1,906,993
Current liabilities:
Accounts payable	140,792	117,706
Accrued interest	19,945	10,621
Accrued tax liability	892	913
Risk management liabilities	7,285	9,357
Other current liabilities	33,948	14,495
Total current liabilities	202,862	153,092
Long-term debt	904,525	592,736
Deferred tax liability	2,135	1,883
Risk management and other noncurrent liabilities	2,150	4,525
Members'/Partners' capital:
Common units	1,164,399	1,161,652
Paid-in capital	59,250	51,743
Accumulated deficit	(592,676)	(313,454)
Accumulated other comprehensive loss	(9,913)	(30,356)
Members'/Partners' capital	906,228	1,154,757	1,196,850	860,026
Total liabilities and members'/partners' capital	2,017,900	1,906,993
Series A Preferred Unit | Parent [Member]
Members'/Partners' capital:
Series A convertible preferred units	285,168	285,172
Parent [Member]
Current assets:
Cash and cash equivalents	4,142	9,650	47,853	3,861
Accounts receivable, net	2	14
Intercompany receivable	128,659	35,178
Risk management assets	0	0
Prepayments and other current assets	1,916	3,378
Total current assets	134,719	48,220
Property, plant and equipment, net	26	56
Intangible assets, net	0	0
Investments in unconsolidated affiliates	0	0
Investment in consolidated subsidiaries	1,683,951	1,703,940
Escrow cash	0	0
Risk management assets	0	0
Other assets, net	21,831	13,128
Total assets	1,840,527	1,765,344
Current liabilities:
Accounts payable	1,458	17
Accrued interest	19,945	10,621
Accrued tax liability	892	913
Risk management liabilities	0	0
Other current liabilities	5,343	4,266
Total current liabilities	27,638	15,817
Long-term debt	904,525	592,736
Deferred tax liability	2,048	1,848
Risk management and other noncurrent liabilities	88	186
Members'/Partners' capital:
Common units	1,164,399	1,161,652
Paid-in capital	59,250	51,743
Accumulated deficit	(592,676)	(313,454)
Accumulated other comprehensive loss	(9,913)	(30,356)
Members'/Partners' capital	906,228	1,154,757
Total liabilities and members'/partners' capital	1,840,527	1,765,344
Series A Preferred Unit | Co-Issuer [Member]
Members'/Partners' capital:
Series A convertible preferred units	0	0
Co-Issuer [Member]
Current assets:
Cash and cash equivalents	0	0	0	(1)
Accounts receivable, net	0	0
Intercompany receivable	(1)	(1)
Risk management assets	0	0
Prepayments and other current assets	0	0
Total current assets	(1)	(1)
Property, plant and equipment, net	0	0
Intangible assets, net	0	0
Investments in unconsolidated affiliates	0	0
Investment in consolidated subsidiaries	0	0
Escrow cash	0	0
Risk management assets	0	0
Other assets, net	0	0
Total assets	(1)	(1)
Current liabilities:
Accounts payable	0	0
Accrued interest	0	0
Accrued tax liability	0	0
Risk management liabilities	0	0
Other current liabilities	0	0
Total current liabilities	0	0
Long-term debt	0	0
Deferred tax liability	0	0
Risk management and other noncurrent liabilities	0	0
Members'/Partners' capital:
Common units	0	0
Paid-in capital	1	1
Accumulated deficit	(2)	(2)
Accumulated other comprehensive loss	0	0
Members'/Partners' capital	(1)	(1)
Total liabilities and members'/partners' capital	(1)	(1)
Series A Preferred Unit | Guarantor Subsidiaries [Member]
Members'/Partners' capital:
Series A convertible preferred units	0	0
Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	49,392	50,280	53,928	40,832
Accounts receivable, net	108,337	96,648
Intercompany receivable	(128,658)	(35,177)
Risk management assets	12,101	7,836
Prepayments and other current assets	6,395	1,801
Total current assets	47,567	121,388
Property, plant and equipment, net	1,078,922	912,101
Intangible assets, net	179,992	188,585
Investments in unconsolidated affiliates	529,958	604,304
Investment in consolidated subsidiaries	0	0
Escrow cash	1,850	1,856
Risk management assets	17,128	11,943
Other assets, net	5,908	5,413
Total assets	1,861,325	1,845,590
Current liabilities:
Accounts payable	139,334	117,689
Accrued interest	0	0
Accrued tax liability	0	0
Risk management liabilities	7,285	9,357
Other current liabilities	28,605	10,229
Total current liabilities	175,224	137,275
Long-term debt	0	0
Deferred tax liability	87	35
Risk management and other noncurrent liabilities	2,866	4,339
Members'/Partners' capital:
Common units	0	0
Paid-in capital	1,214,619	1,162,543
Accumulated deficit	479,246	571,754
Accumulated other comprehensive loss	(9,913)	(30,356)
Members'/Partners' capital	1,683,952	1,703,941
Total liabilities and members'/partners' capital	1,861,325	1,845,590
Series A Preferred Unit | Investment in Non-Guarantor Subsidiaries [Member]
Members'/Partners' capital:
Series A convertible preferred units	0	0
Investment in Non-Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	106,180	85,851	79,450	59,896
Accounts receivable, net	0	0
Intercompany receivable	0	0
Risk management assets	0	0
Prepayments and other current assets	0	0
Total current assets	0	0
Property, plant and equipment, net	0	0
Intangible assets, net	0	0
Investments in unconsolidated affiliates	529,958	604,304
Investment in consolidated subsidiaries	0	0
Escrow cash	0	0
Risk management assets	0	0
Other assets, net	0	0
Total assets	529,958	604,304
Current liabilities:
Accounts payable	0	0
Accrued interest	0	0
Accrued tax liability	0	0
Risk management liabilities	0	0
Other current liabilities	0	0
Total current liabilities	0	0
Long-term debt	0	0
Deferred tax liability	0	0
Risk management and other noncurrent liabilities	0	0
Members'/Partners' capital:
Common units	0	0
Paid-in capital	686,219	602,055
Accumulated deficit	(156,333)	2,249
Accumulated other comprehensive loss	0	0
Members'/Partners' capital	529,958	604,304
Total liabilities and members'/partners' capital	529,958	604,304
Series A Preferred Unit | Eliminations [Member]
Members'/Partners' capital:
Series A convertible preferred units	0	0
Eliminations [Member]
Current assets:
Cash and cash equivalents	(106,180)	(85,851)	(79,450)	(59,896)
Accounts receivable, net	0	0
Intercompany receivable	0	0
Risk management assets	0	0
Prepayments and other current assets	0	0
Total current assets	0	0
Property, plant and equipment, net	0	0
Intangible assets, net	0	0
Investments in unconsolidated affiliates	(529,958)	(604,304)
Investment in consolidated subsidiaries	(1,683,951)	(1,703,940)
Escrow cash	0	0
Risk management assets	0	0
Other assets, net	0	0
Total assets	2,213,909	(2,308,244)
Current liabilities:
Accounts payable	0	0
Accrued interest	0	0
Accrued tax liability	0	0
Risk management liabilities	0	0
Other current liabilities	0	0
Total current liabilities	0	0
Long-term debt	0	0
Deferred tax liability	0	0
Risk management and other noncurrent liabilities	0	0
Members'/Partners' capital:
Common units	0	0
Paid-in capital	(1,900,911)	(1,764,599)
Accumulated deficit	(322,911)	(574,001)
Accumulated other comprehensive loss	9,913	30,356
Members'/Partners' capital	(2,213,909)	(2,308,244)
Total liabilities and members'/partners' capital	(2,213,909)	(2,308,244)
Series A Preferred Unit
Members'/Partners' capital:
Series A convertible preferred units	285,168	285,172
Members'/Partners' capital	$ 285,168	$ 285,172	$ 292,781	$ 0