Condensed Consolidated Balance Sheets (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Current assets:
Cash and cash equivalents	$ 7,012	$ 22,780
Accounts and notes receivable, net:
Trade receivable	21,689	16,351
Accrued revenue and other	198,968	193,647
Fair value of derivative assets	4,811	5,523
Natural gas and natural gas liquids, prepaid expenses and other	13,835	9,780
Total current assets	246,315	248,081
Property and equipment, net of accumulated depreciation of $368,971 and $329,741, respectively	1,226,696	1,216,166
Fair value of derivative assets	88	1,169
Intangible assets, net of accumulated amortization of $173,830 and $151,735, respectively	476,880	498,975
Investment in limited liability company	34,764
Other assets, net	26,446	26,712
Total assets	2,011,189	1,991,103
Current liabilities:
Accounts payable drafts payable, and other	26,834	18,027
Accrued gas purchases	163,011	160,910
Fair value of derivative liabilities	8,303	7,980
Current portion of long-term debt		7,058
Other current liabilities	66,450	66,887
Total current liabilities	264,598	260,862
Long-term debt	764,460	711,512
Other long-term liabilities	25,416	26,879
Deferred tax liability	87,412	89,216
Fair value of derivative liabilities	185	1,156
Commitments and contingencies
Stockholders Equity	869,118	901,478
Total liabilities and stockholders' equity	$ 2,011,189	$ 1,991,103