Equity Method Investments (Summarized Income Statement Information) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
White Cliffs Pipeline, LLC [Member]
Summarized income statement information
Revenue	$ 160,369	$ 133,310	$ 108,125
Operating, general and administrative expenses	23,067	23,825	14,821
Depreciation and amortization expense	23,257	18,668	19,963
Net income	114,045	90,817	73,341
Glass Mountain Pipeline LLC [Member]
Summarized income statement information
Revenue	30,398
Operating, general and administrative expenses	7,176
Depreciation and amortization expense	13,872
Net income	9,344
Ngl Energy Partners Lp [Member]
Summarized income statement information
Revenue				15,748,520	5,935,715	2,371,524
Costs of products sold				15,054,291	5,478,361	2,182,263
Operating, general and administrative expenses				440,609	276,905	125,889
Depreciation and amortization expense				162,443	94,050	34,621
Net income				$ 11,409	$ 44,378	$ 5,405