Rose Rock Midstream, L.P. - Summarized income statement information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Summarized Income Statement Information
Revenue	$ 397,065	$ 594,235	$ 1,072,601	$ 1,575,342
Cost of products sold	274,639	458,063	710,869	1,211,703
Depreciation and amortization	26,022	25,200	74,430	70,899
Earnings from equity method investments	16,237	14,223	60,699	48,372
Net income	9,580	32,196	43,789	39,350
Noncontrolling interests in consolidated subsidiary retained by SemGroup	4,707	6,934	14,153	18,184
Net income attributable to Rose Rock Midstream, L.P.	4,873	25,262	29,636	21,166
Rose Rock Midstream, L.P. [Member]
Summarized Income Statement Information
Revenue	241,086	376,856	599,082	961,526
Cost of products sold	195,244	333,646	464,614	843,928
Operating, general and administrative expenses	23,420	26,574	79,976	69,165
Depreciation and amortization	10,634	8,395	31,385	27,153
Earnings from equity method investments	17,115	16,289	55,662	39,660
Net income	16,421	16,520	48,089	47,834
Noncontrolling interests in consolidated subsidiary retained by SemGroup	0	0	0	7,758
Net income attributable to Rose Rock Midstream, L.P.	$ 16,421	$ 16,520	$ 48,089	$ 40,076