Segment Information (Details Textuals) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Segment Reporting Information [Line Items]
Sales to external customers	$ 445,689	$ 371,709
Purchased gas, NGLs and crude oil	(341,022)	(271,956)
Operating expenses	(37,336)	(27,806)
Gain (loss) on derivatives	(472)	(2,169)
Depreciation And Amortization	(33,745)	(32,196)
Identifiable assets	2,512,634		2,426,475
LIG Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales to external customers	133,057	146,697
Sales to affiliates	29,786	72,810
Purchased gas, NGLs and crude oil	(140,633)	(189,220)
Operating expenses	(7,661)	(7,936)
Segment profit	14,549	22,351
Gain (loss) on derivatives	373	102
Depreciation And Amortization	(3,139)	(3,172)
Capital expenditures	8,232	8
Identifiable assets	286,273	287,879
NTX Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales to external customers	73,450	64,681
Sales to affiliates	16,363	31,484
Purchased gas, NGLs and crude oil	(46,118)	(50,021)
Operating expenses	(14,172)	(13,151)
Segment profit	29,523	32,993
Gain (loss) on derivatives	(775)	(2,263)
Depreciation And Amortization	(19,791)	(20,433)
Capital expenditures	5,023	13,156
Identifiable assets	1,034,580	1,092,530
PNGL Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales to external customers	183,923	160,331
Sales to affiliates	16,427	45,545
Purchased gas, NGLs and crude oil	(175,783)	(182,554)
Operating expenses	(7,218)	(6,719)
Segment profit	17,349	16,603
Gain (loss) on derivatives	(70)	(8)
Depreciation And Amortization	(7,975)	(7,959)
Capital expenditures	96,166	15,662
Identifiable assets	708,989	463,250
ORV Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales to external customers	55,259	0
Sales to affiliates	0	0
Purchased gas, NGLs and crude oil	(41,064)	0
Operating expenses	(8,285)	0
Segment profit	5,910	0
Gain (loss) on derivatives	0	0
Depreciation And Amortization	(2,342)	0
Capital expenditures	15,246	0
Identifiable assets	327,648	0
Corporate Elimination [Member]
Segment Reporting Information [Line Items]
Sales to external customers	0	0
Sales to affiliates	(62,576)	(149,839)
Purchased gas, NGLs and crude oil	(62,576)	(149,839)
Operating expenses	0	0
Segment profit	0	0
Gain (loss) on derivatives	0	0
Depreciation And Amortization	(498)	(634)
Capital expenditures	4,954	454
Identifiable assets	155,144	86,890
Total [Member]
Segment Reporting Information [Line Items]
Sales to external customers	(445,689)	371,709
Sales to affiliates	0	0
Purchased gas, NGLs and crude oil	(341,022)	(271,956)
Operating expenses	(37,336)	(27,806)
Segment profit	67,331	71,947
Gain (loss) on derivatives	(472)	(2,169)
Depreciation And Amortization	(33,745)	(32,198)
Capital expenditures	129,621	29,280
Identifiable assets	$ 2,512,634	$ 1,930,549