Rose Rock Midstream, L.P. - Summarized income statement information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Summarized Income Statement Information
Revenue	$ 377,226	$ 482,224	$ 675,536	$ 981,107
Cost of products sold	244,158	368,527	436,230	753,640
Depreciation and amortization	24,674	22,062	48,408	45,699
Earnings from equity method investments	23,903	19,187	44,462	34,149
Net income	28,433	(12,584)	34,209	7,154
Noncontrolling interests in consolidated subsidiary retained by SemGroup	5,136	5,025	9,446	11,250
Net income attributable to Rose Rock Midstream, L.P.	23,297	(17,609)	24,763	(4,096)
Rose Rock Midstream, L.P. [Member]
Summarized Income Statement Information
Revenue	223,303	292,156	357,996	584,670
Cost of products sold	173,133	255,745	269,370	510,282
Operating, general and administrative expenses	29,985	23,629	56,556	42,591
Depreciation and amortization	10,608	7,276	20,751	18,758
Earnings from equity method investments	17,683	12,291	38,547	23,371
Net income	17,068	15,088	31,668	31,314
Noncontrolling interests in consolidated subsidiary retained by SemGroup	0	4,082	0	7,758
Net income attributable to Rose Rock Midstream, L.P.	$ 17,068	$ 11,006	$ 31,668	$ 23,556