Rose Rock Midstream, L.P. (Details 3) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Summarized Balance Sheet Information
Other current assets	$ 20,017	$ 14,011
Property, plant and equipment	1,256,825	1,105,728
Equity method investments	577,920	565,124
Goodwill	58,326	62,021	9,884	9,453
Other noncurrent assets	44,386	28,889
Total assets	2,589,802	2,470,614
Current liabilities	391,662	499,214
Long-term debt	767,092	615,088
Noncontrolling interest in consolidated subsidiaries retained by SemGroup	69,929	159,961
Total liabilities and owners’ equity	2,589,802	2,470,614
Rose Rock Midstream L P [Member]
Summarized Balance Sheet Information
Cash	3,666	15,459
Other current assets	270,224	306,128
Property, plant and equipment	335,910	311,616
Equity method investments	269,635	224,095
Goodwill	36,116	28,322
Other noncurrent assets	29,677	11,627
Total assets	945,228	897,247
Current liabilities	263,680	293,031
Long-term debt	432,092	245,088
Partners’ capital attributable to SemGroup	179,527	120,610
Limited Partners' Capital Account	69,929
Partners’ capital attributable to noncontrolling interests		159,961
Noncontrolling interest in consolidated subsidiaries retained by SemGroup	0	78,557
Total liabilities and owners’ equity	$ 945,228	$ 897,247