Condensed Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
OPERATING ACTIVITIES:
Net income	$ 56,773	$ 59,991
Adjustments to reconcile net income (loss) to net cash flows provided by operating activities:
Depreciation and amortization, including debt issuance cost and bond premium amortization	146,913	127,079
Income from unconsolidated affiliates	(87,198)	(86,921)
Derivative valuation changes	(17,124)	(21,660)
Loss on asset sales, net	1,542	50
Unit-based compensation expenses	3,470	2,444
Cash flow changes in current assets and liabilities:
Trade accounts receivable, accrued revenues and related party receivables	10,779	(13,298)
Other current assets	(1,429)	186
Trade accounts payable, accrued cost of gas and liquids, related party payables and deferred revenues	(31,675)	20,467
Other current liabilities	7,159	24,833
Distributions received from unconsolidated affiliates	91,893	91,306
Other assets and liabilities	(178)	(61)
Net cash flows provided by operating activities	180,925	204,416
INVESTING ACTIVITIES:
Capital expenditures	(306,159)	(290,889)
Capital contributions to unconsolidated affiliates	(272,759)	(23,646)
Acquistions of investments in unconsolidated affiliates, net of cash received	0	(593,843)
Distribution in excess of earnings of unconsolidated affiliates	49,814	40,354
Proceeds from asset sales	22,004	10,232
Net cash flows used in investing activities	(507,100)	(857,792)
FINANCING ACTIVITIES:
Net borrowings under revolving credit facility	363,000	160,000
Proceeds from issuance of senior notes	0	500,000
Redemption of senior notes	(87,500)	0
Debt issuance costs	(1,438)	(9,955)
Drafts payable	(2,507)	0
Partner distributions	(240,304)	(199,640)
Transfer of assets between entities under common control in excess of historical cost	436	66
Contributions from noncontrolling interest	23,836	0
Issuance of common units under LTIP, net of forfeitures and tax withholding	(207)	655
Common unit offering, net of costs	296,817	203,917
Common units issued under equity distribution program, net of costs	15,352	0
Distributions to Series A Preferred Units	(5,836)	(5,836)
Net cash flows provided by financing activities	361,649	649,207
Net change in cash and cash equivalents	35,474	(4,169)
Cash and cash equivalents at beginning of period	990	9,400
Cash and cash equivalents at end of period	36,464	5,231
Supplemental Cash Flow Information:
Accrued capital expenditures and contributions to unconsolidated affiliates	41,668	25,504
Deemed contribution from acquisition of assets between entities under common control	$ 0	$ 177