CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash Flows From Operating Activities:
Net loss	$ (138,970)	$ (156,312)	$ (8,681)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	77,104	69,156	62,572
Impairment	29,486	8,409
Amortization of debt issue costs	3,999	3,764	3,755
Equity in loss from unconsolidated affiliates	137,088	145,324	20,480
Distributions from unconsolidated affiliates	43,031	31,623	22,416
Gain on sale of operating assets	(9,941)
Loss on refinancing of unsecured debt		18,233
Non-cash gain on risk management activities, net	(2,996)	(3,523)	(984)
Equity-based compensation	8,195	11,558	9,311
Deferred tax provision	295	317	21
Other non-cash items, net	4,870	162	(504)
Changes in assets and liabilities:
Accounts receivable	(6,725)	(19,475)	(4,780)
Prepayments and other current assets	(441)	245	(242)
Risk management activities	10,627	18,343	13,345
Accounts payable	(6,999)	29,812	6,626
Other current liabilities	202	(6,404)	263
Net cash provided by operating activities	148,825	151,232	123,598
Cash Flows From Investing Activities:
Additions to property, plant and equipment	(322,251)	(218,929)	(117,875)
Additions to intangible assets	(10,389)	(20,698)	(9,828)
Acquisitions		(16,084)
Investments in unconsolidated affiliates	(72,313)	(121,967)	(33,002)
Distributions from unconsolidated affiliates	4,443	3,848	3,539
Escrow cash		8	2
Proceeds from sale of assets	24,124	260	447
Other, net	2,492	(2,752)	(13)
Net cash used in investing activities	(373,894)	(376,314)	(156,730)
Cash Flows From Financing Activities:
Proceeds from long-term debt	530,375	825,000	100,000
Repayment of long-term debt	(523,000)	(422,665)	(360,000)
Payments of premiums and expenses on redemption of unsecured debt		(14,572)
Deferred financing costs	(3,540)	(15,783)	(995)
Distributions to unitholders	(171,586)	(153,062)	(145,531)
Proceeds from issuance of Series A convertible preferred units, net of underwriting discounts and commissions of $8,935			291,065
Proceeds from public offering of common units, net of underwriting discounts and commissions of $15,421 and $7,223 for the years ended December 31, 2012 and 2010, respectively	405,355		164,786
Equity offering costs	(15,910)	(5)	(6,395)
Proceeds from option exercises	1,331	3,201	5,440
Net cash provided by financing activities	223,025	222,114	48,370
Net increase (decrease) in cash and cash equivalents	(2,044)	(2,968)	15,238
Cash and cash equivalents, beginning of year	56,962	59,930	44,692
Cash and cash equivalents, end of year	$ 54,918	$ 56,962	$ 59,930