Document and Entity Information	9 Months Ended
	Sep. 30, 2013	Nov. 05, 2013 Common Units	Nov. 05, 2013 Class B Units
Entity Registrant Name	MARKWEST ENERGY PARTNERS L P
Entity Central Index Key	0001166036
Document Type	10-Q
Document Period End Date	Sep. 30, 2013
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		150,492,389	15,963,512
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q3