Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2014	Jun. 30, 2014	Jan. 30, 2015
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2014
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2014
Entity Registrant Name	SemGroup Corporation
Entity Central Index Key	0001489136
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Well-known Seasoned Issuer	Yes
Entity Public Float		$ 3,333,280,930
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Class A [Member]
Entity Common Stock, Shares Outstanding			43,825,556
Class B
Entity Common Stock, Shares Outstanding			0