Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 14,286	$ 2,976
Accounts receivable:
Trade, net of allowance for bad debt of $683 and $535, respectively	69,136	63,690
Accrued revenue and other	138,404	155,828
Fair value of derivative assets	2,698	3,234
Natural gas and natural gas liquids inventory, prepaid expenses and other	14,499	11,866
Assets held for disposition	0	22,599
Total current assets	239,023	260,193
Property and equipment, net of accumulated depreciation of $526,858 and $504,442, respectively	1,578,641	1,472,161
Fair value of derivative assets	9	0
Intangible assets, net of accumulated amortization of $274,633 and $263,305, respectively	413,676	425,005
Goodwill	152,323	152,627
Investment in limited liability company	98,968	90,500
Other assets, net	29,994	25,989
Total assets	2,512,634	2,426,475
Current liabilities:
Accounts payable, drafts payable, and other	26,267	32,265
Accrued gas and crude oil purchases	123,368	140,344
Fair value of derivative liabilities	255	1,310
Other current liabilities	76,133	71,916
Accrued interest	14,971	26,712
Liabilities held for disposition	0	3,572
Total current liabilities	240,994	276,119
Long-term debt	999,780	1,036,305
Other long-term liabilities	29,543	30,256
Deferred tax liability	129,270	133,555
Fair value of derivative liabilities	12	0
Stockholders Equity	1,113,035	950,240
Total liabilities and stockholders' equity	$ 2,512,634	$ 2,426,475