Segment Information (Details Textuals) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Segment Reporting Information [Line Items]
Sales to external customers	$ 406,968	$ 517,498	$ 1,129,871	$ 1,533,003
Purchased gas, NGLs and crude oil	307,223	426,539	840,070	1,255,650
Operating expenses	35,551	28,126	93,928	81,083
Gain (loss) on derivatives	759	563	(1,977)	5,520
Depreciation Depletion Amortization And Impairment	(45,078)	(31,930)	(110,163)	(93,257)
Identifiable assets	2,353,874		2,353,874		1,962,616
LIG Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales to external customers	141,977	200,161	410,154	624,558
Sales to affiliates	50,304	22,059	183,529	68,110
Purchased gas, NGLs and crude oil	(166,374)	(189,393)	(509,196)	(596,313)
Operating expenses	(8,468)	(8,944)	(25,164)	(25,912)
Segment profit	17,439	23,883	59,323	70,443
Gain (loss) on derivatives	(498)	(509)	4,145	(4,463)
Depreciation Depletion Amortization And Impairment	(4,379)	(3,216)	(10,747)	(10,423)
Capital expenditures	1,596	58	3,484	2,738
Identifiable assets	281,891	304,906	281,891	304,906
NTX Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales to external customers	65,606	83,684	191,523	252,462
Sales to affiliates	22,278	26,755	70,988	69,635
Purchased gas, NGLs and crude oil	(41,807)	(67,041)	(123,284)	(194,560)
Operating expenses	(14,255)	(11,957)	(41,549)	(35,417)
Segment profit	31,822	31,441	97,678	92,120
Gain (loss) on derivatives	(293)	(225)	(2,709)	(1,319)
Depreciation Depletion Amortization And Impairment	(21,508)	(19,861)	(62,950)	(56,325)
Capital expenditures	7,596	8,205	41,050	43,216
Identifiable assets	1,067,591	1,092,754	1,067,591	1,092,754
PNGL Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales to external customers	146,448	233,653	475,257	655,983
Sales to affiliates	35,209	82	120,997	773
Purchased gas, NGLs and crude oil	(166,288)	(219,001)	(542,559)	(603,295)
Operating expenses	(7,306)	(7,225)	(21,693)	(19,754)
Segment profit	8,063	7,509	32,002	33,707
Gain (loss) on derivatives	32	171	541	262
Depreciation Depletion Amortization And Impairment	(16,503)	(7,859)	(32,531)	(23,400)
Capital expenditures	34,064	3,362	79,981	12,998
Identifiable assets	538,427	475,580	538,427	475,580
ORV Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales to external customers	52,937	0	52,937	0
Sales to affiliates	0	0	0	0
Purchased gas, NGLs and crude oil	(40,545)	0	(40,545)	0
Operating expenses	(5,522)	0	(5,522)	0
Segment profit	6,870	0	6,870	0
Gain (loss) on derivatives	0	0	0	0
Depreciation Depletion Amortization And Impairment	(2,164)	0	(2,164)	0
Capital expenditures	556	0	556	0
Identifiable assets	318,258	0	318,258	0
Corporate Elimination [Member]
Segment Reporting Information [Line Items]
Sales to external customers	0	0	0	0
Sales to affiliates	(107,791)	(48,896)	(375,514)	(138,518)
Purchased gas, NGLs and crude oil	107,791	48,896	375,514	138,518
Operating expenses	0	0	0	0
Segment profit	0	0	0	0
Gain (loss) on derivatives	0	0	0	0
Depreciation Depletion Amortization And Impairment	(524)	(994)	(1,771)	(3,109)
Capital expenditures	5,573	660	7,109	1,862
Identifiable assets	$ 147,707	$ 77,529	$ 147,707	$ 77,529