Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Segment Reporting Information [Line Items]
Revenues	$ 454,737	$ 394,402	$ 900,427	$ 820,361
Purchased gas, NGLs and crude oil	(359,093)	(304,098)	(700,115)	(630,304)
Operating expenses	(36,862)	(30,571)	(74,200)	(58,378)
Gain (loss) on derivatives	445	4,905	(27)	2,736
Depreciation and amortization	(34,673)	(32,889)	(68,417)	(65,085)
Identifiable assets	2,676,237		2,676,237		2,426,475
LIG Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues	119,725	121,479	252,782	268,177
Sales to affiliates	16,119	60,415	45,906	133,225
Purchased gas, NGLs and crude oil	(115,395)	(153,601)	(256,028)	(342,822)
Operating expenses	(7,813)	(8,759)	(15,474)	(16,696)
Segment profit	12,636	19,534	27,186	41,884
Gain (loss) on derivatives	582	4,541	955	4,643
Depreciation and amortization	(3,170)	(3,200)	(6,308)	(6,372)
Capital expenditures	7,935	1,886	16,167	1,888
Identifiable assets	281,852	280,090	281,852	280,090
NTX Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues	85,360	61,236	158,809	125,917
Sales to affiliates	17,108	17,227	33,470	48,711
Purchased gas, NGLs and crude oil	(59,677)	(31,457)	(105,795)	(81,478)
Operating expenses	(12,474)	(14,144)	(26,646)	(27,295)
Segment profit	30,317	32,862	59,838	65,855
Gain (loss) on derivatives	(271)	(153)	(1,046)	(2,416)
Depreciation and amortization	(19,850)	(21,009)	(39,641)	(41,442)
Capital expenditures	2,229	20,295	7,252	33,451
Identifiable assets	1,024,118	1,086,299	1,024,118	1,086,299
PNGL Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues	185,562	211,687	369,485	426,267
Sales to affiliates	92	40,243	16,519	85,787
Purchased gas, NGLs and crude oil	(166,906)	(236,925)	(342,689)	(473,727)
Operating expenses	(8,003)	(7,668)	(15,220)	(14,387)
Segment profit	10,745	7,337	28,095	23,940
Gain (loss) on derivatives	314	517	244	509
Depreciation and amortization	(8,215)	(8,069)	(16,190)	(16,028)
Capital expenditures	131,499	30,255	227,665	45,917
Identifiable assets	842,767	498,888	842,767	498,888
ORV Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues	64,090	0	119,351	0
Sales to affiliates	0	0	0	0
Purchased gas, NGLs and crude oil	(50,434)	0	(91,498)	0
Operating expenses	(8,572)	0	(16,860)	0
Segment profit	5,084	0	10,993	0
Gain (loss) on derivatives	(180)	0	(180)	0
Depreciation and amortization	(2,768)	0	(5,110)	0
Capital expenditures	22,852	0	38,097	0
Identifiable assets	348,439	0	348,439	0
Corporate Elimination [Member]
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Sales to affiliates	(33,319)	(117,885)	(95,895)	(267,723)
Purchased gas, NGLs and crude oil	33,319	117,885	95,895	267,723
Operating expenses	0	0	0	0
Segment profit	0	0	0	0
Gain (loss) on derivatives	0	0	0	0
Depreciation and amortization	(670)	(611)	(1,168)	(1,243)
Capital expenditures	988	1,076	5,942	1,536
Identifiable assets	179,061	383,160	179,061	383,160
Total [Member]
Segment Reporting Information [Line Items]
Revenues	454,737	394,402	900,427	820,361
Sales to affiliates	0	0	0	0
Purchased gas, NGLs and crude oil	(359,093)	(304,098)	(700,115)	(630,304)
Operating expenses	(36,862)	(30,571)	(74,200)	(58,378)
Segment profit	58,782	59,733	126,112	131,679
Gain (loss) on derivatives	445	4,905	(27)	2,736
Depreciation and amortization	(34,673)	(32,889)	(68,417)	(65,085)
Capital expenditures	165,503	53,512	295,123	82,792
Identifiable assets	$ 2,676,237	$ 2,248,437	$ 2,676,237	$ 2,248,437