Investments in Non-Consolidated Subsidiaries (Details Textual) (USD $)	1 Months Ended	3 Months Ended								12 Months Ended			9 Months Ended	12 Months Ended				0 Months Ended	1 Months Ended	12 Months Ended			1 Months Ended	8 Months Ended	12 Months Ended		0 Months Ended			0 Months Ended
	Sep. 30, 2010	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Sep. 30, 2010 White Cliffs Pipeline, LLC [Member]	Dec. 31, 2012 White Cliffs Pipeline, LLC [Member] mi		Dec. 31, 2011 White Cliffs Pipeline, LLC [Member]	Dec. 31, 2010 White Cliffs Pipeline, LLC [Member]	Nov. 01, 2011 Ngl Energy Partners Lp [Member]	Jun. 30, 2012 Ngl Energy Partners Lp [Member]	Dec. 31, 2012 Ngl Energy Partners Lp [Member]	Sep. 30, 2012 Ngl Energy Partners Lp [Member]	Oct. 31, 2011 Ngl Energy Partners Lp [Member]	Sep. 30, 2012 Glass Mountain Pipeline LLC [Member]	Dec. 31, 2012 Glass Mountain Pipeline LLC [Member] mi	Dec. 31, 2012 Glass Mountain Pipeline LLC [Member]	May 31, 2012 Glass Mountain Pipeline LLC [Member]	Nov. 01, 2011 General Partner Interest [Member] Ngl Energy Partners Lp [Member]	Dec. 31, 2012 Limited Partner [Member] SemStream [Member] Ngl Energy Partners Lp [Member]	Dec. 31, 2012 General Partner [Member] SemStream [Member] Ngl Energy Partners Lp [Member]	Jan. 11, 2013 Subsequent Event [Member] Width	Jan. 11, 2013 Subsequent Event [Member] White Cliffs Pipeline, LLC [Member]	Jan. 11, 2013 Subsequent Event [Member] Semcrude Pipeline [Member] White Cliffs Pipeline, LLC [Member]	Jan. 08, 2013 Subsequent Event [Member] Semcrude Pipeline [Member] White Cliffs Pipeline, LLC [Member]
Investment in Non Consolidated Subsidiaries (Textual) [Abstract]
Percentage of ownership before transaction													99.00%
Percentage of ownership after transaction														51.00%
Width of Pipeline																														12
Estimated future developement costs		$ 300,000,000								$ 300,000,000
Project funding contributions		2,300,000
General and administrative										71,918,000	75,447,000	85,836,000		2,000,000		3,200,000	900,000
Gain (loss) on sale of discontinued operations	(6,800,000)
Loss on settlement														3,500,000	[1]
Common units acquired																		8,932,031
Interest in partner, percent																											7.50%
Common units representing limited partner interests																					50,769,785							9,133,409
Estimated capital account																						184,000,000
Number of common units received due to Dilution																			201,378
Proceeds from dividends received																				9,200,000
Percentage of ownership interest														51.00%										50.00%	50.00%	25.00%		18.00%	6.42%		17.00%	51.00%	51.00%
Estimated project contributions in 2013		119,300,000								119,300,000
Estimated project contributions in 2014		29,500,000								29,500,000
Value of common units acquired																				213,000,000
Length of pipeline network (in miles)														527										210
Share Price																				23.32
Additional ownership percentage																							25.00%
Additional cash capital contribution																									74,400,000
Equity In Earning		13,133,000	3,116,000	12,289,000	7,498,000	4,838,000	4,016,000	4,086,000	2,064,000	36,036,000	15,004,000	1,949,000								400,000
Additional cash capital contribution in 2013																								$ 51,600,000	$ 51,600,000

[1] We sold a portion of our ownership interest in White Cliffs during September 2010. At the time, we recorded a loss of $6.8 million on disposal of that asset. In September 2012, we reached a settlement in a dispute concerning the selling price of that ownership interest and reduced the loss by $3.5 million. This $3.5 million gain is reported in gain on disposal or impairment of long-lived assets, net in the consolidated statements of operations and comprehensive income (loss).