2.2.0.25falsefalse1040 - Disclosure - Variable Interest Entitiestruefalsefalse1falsefalseUSDfalsefalse1/1/2010 - 12/31/2010 USD ($) USD ($) / shares $D2010http://www.sec.gov/CIK0001166036duration2010-01-01T00:00:002010-12-31T00:00:00USDStandardhttp://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>         On February 27, 2009, the Partnership entered into a joint venture with M&R MWE Liberty LLC ("M&R"), an affiliate of The Energy & Minerals Group and its affiliated funds, which is a private equity firm focused on investments in selected areas of the energy infrastructure and natural resources sectors. The joint venture entity, MarkWest Liberty Midstream, operates in the natural gas midstream business in and around the Marcellus Shale in western Pennsylvania and northern West Virginia. The Partnership contributed its existing Marcellus Shale natural gas gathering and processing assets to MarkWest Liberty Midstream in exchange for a 60% ownership interest. The agreed-to value of the contributed assets was approximately $107.5 million. At closing, M&R contributed cash of $50.0 million in exchange for a 40% ownership interest. A wholly-owned subsidiary of the Partnership serves as the operator of MarkWest Liberty Midstream and provides field operating and general and administrative services. A portion of the fee for providing these services is fixed.         Effective November 1, 2009, the Partnership and M&R executed the Amended Liberty Agreement pursuant to which M&R increased its participation in MarkWest Liberty Midstream. The Partnership and M&R agreed to maintain a 60%/40% respective ownership interest in MarkWest Liberty Midstream until January 1, 2011, at which time M&R's ownership interest will increase from 40% to 49%. The Partnership and M&R agreed to jointly fund the capital requirements of MarkWest Liberty Midstream at agreed upon levels until the Partnership's contributed capital is proportionate to its eventual 51% ownership interest (the "Equalization Date"), which is required to occur on or before December 31, 2012. The Partnership is required to reinvest all cash distributions from MarkWest Liberty Midstream until the Equalization Date has occurred. If the Equalization Date has not occurred by the end of 2012, M&R may require the Partnership to contribute the amount of the shortfall at December 31, 2012, or may allow the Partnership to continue to fund 100% of MarkWest Liberty Midstream's capital expenditures until its total contributed capital is proportionate to its ownership interest. Following the Equalization Date, M&R will have pre-emptive rights to maintain its ownership interest in MarkWest Liberty Midstream in a range of between 45% and 49% or have its ownership interest diluted to the extent that it elects not to fund its proportionate share.         During 2009, M&R and the Partnership contributed an additional $150.0 million and $8.0 million, respectively, to fund the capital expenditures of MarkWest Liberty Midstream. During 2010, M&R and the Partnership contributed $158.3 million and $171.1 million, respectively, to the entity. As of December 31, 2010, 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 $120.2 million as of December 31, 2010. Under the terms of the joint venture agreement, M&R received a special $11.4 million and $3.4 million non-cash allocation of net income from MarkWest Liberty Midstream during the years ended December 31, 2010 and 2009, respectively, due to its excess contributions. The non-cash allocation is recorded in Net income attributable to non-controlling interest.         The Partnership has determined that MarkWest Liberty Midstream is a VIE primarily due to the Partnership's disproportionate economic interests as compared to its voting interests in the entity. The Partnership has made capital contributions that differ from its stated ownership interests. Additionally, MarkWest Liberty Midstream has insufficient equity at risk, as evidenced by the additional capital funding requirements discussed above.         Although voting interests are shared equally between the respective members of MarkWest Liberty Midstream, the Partnership has concluded that it is the primary beneficiary based on its affiliate's role as the operator. The Partnership believes that its role as the operator along with its equity interests give it the power to direct the activities that most significantly affect the economic performance of MarkWest Liberty Midstream.         As a result of the execution of the Amended Liberty Agreement, the Partnership reconsidered the accounting treatment for MarkWest Liberty Midstream as a VIE and determined that the conclusions as discussed above remain unchanged. <ul> <li style="list-style: none"> MarkWest Pioneer</li></ul>         MarkWest Pioneer is the owner and operator of the Arkoma Connector Pipeline, a 50-mile FERC-regulated pipeline that was placed in service in mid-July 2009. The Arkoma Connector Pipeline is designed to provide approximately 638,000 Dth/d of Arkoma Basin takeaway capacity and interconnects with the Midcontinent Express Pipeline and the Gulf Crossing Pipeline. A wholly-owned subsidiary of the Partnership serves as the operator and provides field operating and general and administrative services for fixed fees.         On May 1, 2009, the Partnership entered into a joint venture with Arkoma Pipeline Partners, LLC ("ArcLight"), an affiliate of ArcLight Capital Partners, LLC which is an investment firm focused on opportunities throughout the energy industry. ArcLight acquired a 50% equity interest in MarkWest Pioneer for a total purchase price of $62.5 million. The Partnership retained a 50% equity interest and was obligated to fund all capital expenditures necessary to complete construction of the Arkoma Connector Pipeline in excess of $125.0 million (the "Excess Capital Expenditures"). As a result of the Excess Capital Expenditures, the Partnership recorded a $10.3 million equity loss, net of a $1.5 million tax benefit, that is reflected as a transfer to non-controlling interest, and the Partnership's recorded ownership interest as of December 31, 2010 exceeds its stated ownership interest in MarkWest Pioneer by approximately $1.8 million. The difference between the carrying value of the Partnership's ownership interest and its stated ownership interest is amortized based upon the respective useful lives of the assets to which the difference relates.         The Partnership has determined that MarkWest Pioneer is a VIE primarily due to the Partnership's disproportionate economic interests as compared to its voting interests in each entity. Due to the funding of the Excess Capital Expenditures, the Partnership has made capital contributions to MarkWest Pioneer that differ from its stated ownership interests. Although voting interests are shared equally between the respective members of MarkWest Pioneer, the Partnership has concluded that it is the primary beneficiary based on its affiliate's role as the operator. The Partnership believes that its role as the operator along with its equity interests give it the power to direct the activities that most significantly affect the economic performance of MarkWest Pioneer. <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 reflected in the Partnership's Consolidated Balance Sheets as of December 31, 2010 and 2009 (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 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>   <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, 2009 </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">$</td> <td style="FONT-FAMILY: times" align="right">18,168</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">3,774</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">21,942</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">20,753</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">1,280</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">22,033</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">3,343</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">3,343</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">225</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">327</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 $8,273 and $3,051, respectively</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right"> 330,116</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right"> 153,478</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right"> 483,594</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times" colspan="2"> Other long-term assets</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">314</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right"></td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">314</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="FONT-SIZE: 1.5pt; HEIGHT: 0px" valign="top"> <td style="FONT-FAMILY: times" valign="bottom" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td> <td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"> </td> <td style="FONT-FAMILY: times" valign="bottom"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> Total assets</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">372,919</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">158,634</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">531,553</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="#CCEEFF"> <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="white"> <td style="FONT-FAMILY: times" colspan="2"> Accounts payable</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">2,713</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">32</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">2,745</td> <td style="FONT-FAMILY: times"> </td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <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">43,136</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">1,479</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">44,615</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 liabilities</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">80</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">285</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">365</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 liabilities</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">45,929</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">1,796</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">47,725</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 MarkWest Liberty Midstream and MarkWest Pioneer are the property of the respective entities and are not available to the Partnership for any other purpose, including collateral for its secured debt (see Note 17 and Note 26). VIE asset balances can only be used to settle obligations of each respective VIE. The liabilities of MarkWest Liberty Midstream and MarkWest Pioneer 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 (see Note 25). The Partnership's Southwest segment includes the results of operations of MarkWest Pioneer (see Note 25). 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 26). 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 subsidiary's compensation for the performance of those services. The Partnership did not provide any financial support to the VIEs that it was not contractually obligated to provide during the years ended December 31, 2010 and 2009.         The following table shows the net income (loss) attributable to the Partnership and transfers to the non-controlling interests for the years ended December 31, 2010 and 2009 (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" 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="88"></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="88"></td> <td style="FONT-FAMILY: times" width="12"></td></tr> <tr style="HEIGHT: 0px" valign="bottom"> <th style="FONT-FAMILY: times" align="left" colspan="3">  </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="2">Year ended December 31, 2010 </th> <th style="FONT-FAMILY: times"> </th> <th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="2">Year ended December 31, 2009 </th> <th style="FONT-FAMILY: times"> </th></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="#CCEEFF"> <td style="FONT-FAMILY: times" colspan="3"> Net income (loss) attributable to the Partnership</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">467</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">(118,668</td> <td style="FONT-FAMILY: times">)</td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" colspan="2"> Transfers to the non-controlling interests:</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"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> Decrease in Partners' Capital for transaction costs related to sale of equity interest in MarkWest Liberty Midstream and MarkWest Pioneer</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"> (7,310</td> <td style="FONT-FAMILY: times"> )</td></tr> <tr style="HEIGHT: 0px" valign="bottom" bgcolor="white"> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times"> Decrease in Partners' Capital for transfer to non-controlling interest from sale of equity interest in MarkWest Pioneer(1)</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"> (10,288</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="3"> </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" colspan="3"> Net income (loss) attributable to the Partnership and transfers to the non-controlling interest</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">467</td> <td style="FONT-FAMILY: times"> </td> <td style="FONT-FAMILY: times" align="right">$</td> <td style="FONT-FAMILY: times" align="right">(136,266</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="3"> </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%; PADDING-TOP: 0pt; POSITION: relative; TEXT-ALIGN: left"> <hr style="COLOR: #000000" align="left" width="26%" noshade="noshade" size="1" /> <dl compact="compact"> <dt style="MARGIN-BOTTOM: -11pt; FONT-FAMILY: times">(1)</dt> <dd style="FONT-FAMILY: times">Decrease in Partners' Capital for transfer to non-controlling interest is determined based on the amount of Excess Capital Expenditures as estimated on the closing date. As of December 31, 2009, the decrease is shown net of tax benefit. </dd></dl></div></td></tr></table> 4. Variable Interest Entities MarkWest Liberty Midstream         On February 27, 2009, the Partnership enteredfalsefalsefalsefalsefalseOtherus-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