Equity Method Investments (Summarized Income Statement Information) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013
White Cliffs Pipeline, LLC [Member]
Summarized income statement information
Revenue	$ 206,395		$ 160,369		$ 133,310
Operating, general and administrative expenses	33,284		23,067		23,825
Depreciation and amortization expense	34,105		23,257		18,668
Net income	139,000		114,045		$ 90,817
Glass Mountain Pipeline LLC [Member]
Summarized income statement information
Revenue	38,526		30,398
Costs of products sold	3,392		757
Operating, general and administrative expenses	6,643		6,419
Depreciation and amortization expense	15,828		13,872
Net income	$ 12,657		$ 9,344
Ngl Energy Partners Lp [Member]
Summarized income statement information
Revenue		$ 14,504,581		$ 15,748,520		$ 5,935,715
Costs of products sold		13,573,066		15,054,291		5,478,361
Operating, general and administrative expenses		625,035		440,609		276,905
Depreciation and amortization expense		221,067		162,443		94,050
Net income		$ 22,995		$ 11,409		$ 44,378