Document and Entity Information (USD $) In Billions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Jun. 30, 2013	Feb. 19, 2014 Common Units	Feb. 19, 2014 Class B Units
Entity Registrant Name	MARKWEST ENERGY PARTNERS L P
Entity Central Index Key	0001166036
Document Type	10-K
Document Period End Date	Dec. 31, 2013
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float		$ 8.9
Entity Common Stock, Shares Outstanding			157,976,406	15,963,512
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	FY