Rose Rock Midstream, L.P. (Details 3) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Summarized Balance Sheet Information
Other current assets	$ 16,285	$ 18,516
Property, plant and equipment, net	833,591	814,724
Equity method investment	466,239	387,802
Other noncurrent assets, net	40,071	8,181
Total assets	2,096,651	1,748,179
Current liabilities	382,748	374,344
Long-term debt	466,549	206,062
Partners' capital attributable to SemGroup	1,003,828	892,394
Partners' capital attributable to noncontrolling interests	98,277	129,134
Total liabilities and owners' equity	2,096,651	1,748,179
Rose Rock Midstream, L.P. [Member]
Summarized Balance Sheet Information
Cash	3,650	108
Other current assets	247,195	250,509
Property, plant and equipment, net	296,084	291,530
Equity method investment	66,037	0
Other noncurrent assets, net	3,792	2,579
Total assets	616,758	544,726
Current liabilities	223,158	231,843
Long-term debt	166,549	4,562
Partners' capital attributable to SemGroup	128,774	179,187
Partners' capital attributable to noncontrolling interests	98,277	129,134
Total liabilities and owners' equity	$ 616,758	$ 544,726