Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash flows from operating activities:
Net income (loss)	$ (1,279)	$ (21,513)	$ 86,105
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization	125,358	111,625	129,812
Non-cash stock-based compensation	7,556	9,569	8,855
(Gain) loss on sale of property	264	(13,881)	(184,412)
Impairments	0	1,311	2,894
Deferred tax (benefit) expense	(4,540)	(7,538)	15,229
Derivatives mark to market interest rate settlement	0	(24,160)	0
Non-cash portion of derivatives loss	761	1,136	2,184
Non-cash portion of loss on debt extinguishment	0	5,396	4,669
Interest paid-in-kind debt	0	(11,558)	10,134
Amortization of debt issue costs	6,462	6,680	11,812
Amortization of discount on notes	1,897	1,686	0
Changes in assets and liabilities:
Accounts receivable, accrued revenue and other	44,121	4,665	127,981
Natural gas and natural gas liquids, prepaid expenses and other	(1,507)	2,376	(5,287)
Accounts payable, accrued gas purchases and other accrued liabilities	(37,800)	18,996	(131,126)
Net cash provided by operating activities	141,293	84,790	78,850
Cash flows from investing activities:
Additions to property and equipment	(97,572)	(48,191)	(101,370)
Insurance recoveries on property and equipment	0	2,599	12,458
Acquisitions and asset purchases	0	0	(35,142)
Proceeds from sale of property	478	60,230	503,928
Investment in limited liability company	(35,000)	0	0
Net cash provided by (used in) investing activities	(132,094)	14,638	379,874
Cash flows from financing activities:
Proceeds from borrowings	471,250	997,412	632,807
Payments on borrowings	(393,308)	(1,144,705)	(1,050,389)
Proceeds from capital lease obligations	0	0	1,695
Payments on capital lease obligations	(3,122)	(2,385)	(2,414)
Increase (decrease) in drafts payable	5,854	(5,063)	(16,300)
Debt refinancing costs	(3,954)	(28,561)	(15,031)
Distributions to non-controlling partners in the Partnership	(58,209)	(18,993)	(7,601)
Common dividends paid	(17,872)	(3,368)	(4,228)
Conversion of restricted units, net of units withheld for taxes	(1,798)	(2,659)	(232)
Conversion of restricted stock, net of shares withheld for taxes	(1,068)	(705)	(354)
Proceeds from issuance of Partnership units	0	120,786	0
Proceeds from exercise of Partnership unit options	591	890	67
Net cash provided by (used in) financing activities	(1,636)	(87,351)	(461,980)
Net decrease in cash and cash equivalents	7,563	12,077	(3,256)
Cash and cash equivalents, beginning of period	22,780	10,703	13,959
Cash and cash equivalents, end of period	30,343	22,780	10,703
Cash paid for interest	71,950	66,081	91,454
Cash paid for income taxes	$ 1,104	$ (33)	$ 926