2.2.0.25falsefalse1040 - Disclosure - Variable Interest Entitiestruefalsefalse1falsefalseUSDfalsefalse1/1/2011 - 3/31/2011 USD ($) USD ($) / shares $D2011Q1http://www.sec.gov/CIK0001166036duration2011-01-01T00:00:002011-03-31T00:00:00USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170SharesStandardhttp://www.xbrl.org/2003/instancesharesxbrli0USDPerShareDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0USDUSD$2true0mwe_VariableInterestEntitiesDisclosureAbstractmwefalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseVariable Interest Entities3false0us-gaap_ScheduleOfVariableInterestEntitiesTextBlockus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1falsefalsefalse00<table style="font-size:10pt; font-family:'Times New Roman',times,serif;"> <tr> <td> 4. Variable Interest Entities <ul> <li style="list-style: none"> MarkWest Liberty Midstream</li></ul>         MarkWest Liberty Midstream operates in the natural gas midstream business in and around the Marcellus Shale in western Pennsylvania and northern West Virginia. Effective January 1, 2011, equity interests in the entity are owned 51% by the Partnership and 49% by M&R MWE Liberty, LLC ("M&R"), an affiliate of The Energy & Minerals Group and its affiliated funds.         As of March 31, 2011, the capital contributed to MarkWest Liberty Midstream is disproportionate to each member's respective ownership interest. The cumulative capital contributed by M&R exceeded its ownership interest by $43.0 million. Under the terms of the joint venture agreement, M&R received a special $1.1 million allocation of net income from MarkWest Liberty Midstream during the first quarter of 2011 due to its excess contributions. The non-cash allocation is recorded in Net income attributable to non-controlling interest. <ul> <li style="list-style: none"> MarkWest Pioneer</li></ul>         MarkWest Pioneer is the owner and operator of the Arkoma Connector Pipeline. Equity interests in the entity are shared equally by the Partnership and Arkoma Pipeline Partners, LLC. <ul> <li style="list-style: none"> Financial Statement Impact of VIEs</li></ul>         As the primary beneficiary of MarkWest Liberty Midstream and MarkWest Pioneer, the Partnership consolidates the entities and recognizes non-controlling interests. The following tables show the assets and liabilities attributable to VIEs as of March 31, 2011 and December 31, 2010 (in thousands): <div style="PADDING-RIGHT: 0pt; PADDING-LEFT: 0pt; PADDING-BOTTOM: 0pt; MARGIN-LEFT: 10%; WIDTH: 80%; PADDING-TOP: 0pt; POSITION: relative">   <div align="center"> <table cellspacing="0" cellpadding="0" width="100%" border="0"> <tr style="HEIGHT: 0px"> <td style="FONT-FAMILY: times" align="left" width="10"></td> <td style="FONT-FAMILY: times" align="left"></td> <td style="FONT-FAMILY: times" width="12"></td> <td style="FONT-FAMILY: times" align="right" width="7"></td> <td style="FONT-FAMILY: times" width="84"></td> <td style="FONT-FAMILY: times" width="12"></td> <td style="FONT-FAMILY: times" align="right" width="7"></td> <td style="FONT-FAMILY: times" width="87"></td> <td style="FONT-FAMILY: times" width="12"></td> <td style="FONT-FAMILY: times" align="right" width="7"></td> <td style="FONT-FAMILY: times" width="51"></td> <td style="FONT-FAMILY: times" width="12"></td></tr> <tr style="HEIGHT: 0px" valign="bottom"> <th style="FONT-FAMILY: times" align="left" colspan="2">  </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="8">As of March 31, 2011 </th> <th style="FONT-FAMILY: times"> </th></tr> <tr style="HEIGHT: 0px" valign="bottom"> <th style="FONT-FAMILY: times" align="left" colspan="2">  </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="2">MarkWest Liberty Midstream </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="2">MarkWest Pioneer </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="2">Total </th> <th style="FONT-FAMILY: times"> </th></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times" align="center" colspan="2"> ASSETS</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times" colspan="2"> Cash and cash equivalents</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">7,369</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">1,668</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">9,037</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times" colspan="2"> Receivables, net</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">12,880</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">1,408</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">14,288</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times" colspan="2"> Inventories</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">4,832</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right"></td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">4,832</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times" colspan="2"> Other current assets</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">77</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right"></td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">77</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times" colspan="2"> Property, plant and equipment, net of accumulated depreciation of $35,572 and $10,862, respectively</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">736,956</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">145,476</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">882,432</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times" colspan="2"> Restricted cash</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">28,052</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right"></td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">28,052</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times" colspan="2"> Other long-term assets</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">275</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">103</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">378</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="FONT-SIZE: 1.5pt; HEIGHT: 0px" valign="top"> <td style="FONT-FAMILY: times" valign="bottom" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> Total assets</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">790,441</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">148,655</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">939,096</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="FONT-SIZE: 1.5pt; HEIGHT: 0px" valign="top"> <td style="FONT-FAMILY: times" valign="bottom" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times" align="center" colspan="2"> LIABILITIES</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times" colspan="2"> Accounts payable</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">10,593</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">80</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">10,673</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times" colspan="2"> Accrued liabilities</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">48,083</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">667</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">48,750</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times" colspan="2"> Other long-term liabilities</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">88</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">69</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">157</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="FONT-SIZE: 1.5pt; HEIGHT: 0px" valign="top"> <td style="FONT-FAMILY: times" valign="bottom" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> Total liabilities</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">58,764</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">816</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">59,580</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="FONT-SIZE: 1.5pt; HEIGHT: 0px" valign="top"> <td style="FONT-FAMILY: times" valign="bottom" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td></tr></table></div> </div>   <div style="PADDING-RIGHT: 0pt; PADDING-LEFT: 0pt; PADDING-BOTTOM: 0pt; MARGIN-LEFT: 10%; WIDTH: 80%; PADDING-TOP: 0pt; POSITION: relative">   <div align="center"> <table cellspacing="0" cellpadding="0" width="100%" border="0"> <tr style="HEIGHT: 0px"> <td style="FONT-FAMILY: times" align="left" width="10"></td> <td style="FONT-FAMILY: times" align="left"></td> <td style="FONT-FAMILY: times" width="12"></td> <td style="FONT-FAMILY: times" align="right" width="7"></td> <td style="FONT-FAMILY: times" width="84"></td> <td style="FONT-FAMILY: times" width="12"></td> <td style="FONT-FAMILY: times" align="right" width="7"></td> <td style="FONT-FAMILY: times" width="87"></td> <td style="FONT-FAMILY: times" width="12"></td> <td style="FONT-FAMILY: times" align="right" width="7"></td> <td style="FONT-FAMILY: times" width="51"></td> <td style="FONT-FAMILY: times" width="12"></td></tr> <tr style="HEIGHT: 0px" valign="bottom"> <th style="FONT-FAMILY: times" align="left" colspan="2">  </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="8">As of December 31, 2010 </th> <th style="FONT-FAMILY: times"> </th></tr> <tr style="HEIGHT: 0px" valign="bottom"> <th style="FONT-FAMILY: times" align="left" colspan="2">  </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="2">MarkWest Liberty Midstream </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="2">MarkWest Pioneer </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="2">Total </th> <th style="FONT-FAMILY: times"> </th></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times" align="center" colspan="2"> ASSETS</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times" colspan="2"> Cash and cash equivalents</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right"></td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">2,913</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">2,913</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times" colspan="2"> Receivables, net</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">42,181</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">1,602</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">43,783</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times" colspan="2"> Inventories</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">8,431</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right"></td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">8,431</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times" colspan="2"> Other current assets</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">271</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">1</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">272</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times" colspan="2"> Property, plant and equipment, net of accumulated depreciation of $28,869 and $9,300, respectively</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">664,778</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">147,039</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">811,817</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times" colspan="2"> Restricted cash</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">28,001</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right"></td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">28,001</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times" colspan="2"> Other long-term assets</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">281</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">102</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">383</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="FONT-SIZE: 1.5pt; HEIGHT: 0px" valign="top"> <td style="FONT-FAMILY: times" valign="bottom" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> Total assets</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">743,943</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">151,657</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">895,600</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="FONT-SIZE: 1.5pt; HEIGHT: 0px" valign="top"> <td style="FONT-FAMILY: times" valign="bottom" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times" align="center" colspan="2"> LIABILITIES</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times" colspan="2"> Accounts payable</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">5,945</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right"></td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">5,945</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times" colspan="2"> Accrued liabilities</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">63,450</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">1,263</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">64,713</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times" colspan="2"> Other long-term liabilities</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">86</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">68</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">154</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="FONT-SIZE: 1.5pt; HEIGHT: 0px" valign="top"> <td style="FONT-FAMILY: times" valign="bottom" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> Total liabilities</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">69,481</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">1,331</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">70,812</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="FONT-SIZE: 1.5pt; HEIGHT: 0px" valign="top"> <td style="FONT-FAMILY: times" valign="bottom" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td></tr></table></div> </div>         The assets of the VIEs are the property of the respective entities and are not available to the Partnership for any other purpose, including as collateral for its secured debt (see Note 9 and Note 16). VIE asset balances can only be used to settle obligations of each respective VIE. The liabilities of the VIEs do not represent additional claims against the Partnership's general assets, and the creditors or beneficial interest holders of the VIE do not have recourse to the general credit of the Partnership. The Partnership's Liberty segment includes the results of operations of MarkWest Liberty Midstream and the Partnership's Southwest segment includes the results of operations of MarkWest Pioneer (see Note 15). The cash flow information for MarkWest Liberty Midstream and MarkWest Pioneer comprise substantially all of the cash flow information of the Partnership's non-guarantor subsidiaries (see Note 16). The Partnership's maximum exposure to loss as a result of its involvement with the VIEs includes its equity investment, any additional capital contribution commitments and any operating expense incurred by the subsidiary operator in excess of its compensation received for the performance of the operating services. The Partnership did not provide any financial support to the VIEs that it was not contractually obligated to provide during the three months ended March 31, 2011 and 2010. </td></tr></table> 4. Variable Interest Entities MarkWest Liberty Midstream         MarkWest Liberty Midstream operates in the naturalfalsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringDisclosure of variable interest entities (VIE), including, but not limited to the nature, purpose, size, and activities of the VIE, the carrying amount and classification of consolidated assets that are collateral for the VIE's obligations, lack of recourse if creditors (or beneficial interest holders) of a consolidated VIE have no recourse to the general credit of the primary beneficiary. An enterprise that holds a significant variable interest in a VIE but is not the primary beneficiary may disclose the nature of its involvement with the VIE and when that involvement began, the nature, purpose, size, and activities of the VIE and the enterprise's maximum exposure to loss as a result of its involvement with the VIE.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 140 -Paragraph 35 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Interpretation (FIN) -Number 46R -Paragraph 2, 14, 15, 16, 23, 24, 25, 26 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Interpretation (FIN) -Number 46R -Paragraph 4 -Subparagraph g Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Staff Position (FSP) -Number FAS140-4 and FIN46(R)-8 -Paragraph C4 -Subparagraph d falsefalseVariable Interest Entities12Variable Interest EntitiesUnKnownUnKnownUnKnownUnKnownfalsetrue