Markwest Energy Partners L P 10-Q 6 Aug 14 2014 Q2 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	6 Months Ended
	Jun. 30, 2014	Jul. 30, 2014	Jul. 30, 2014
		Common Units	Class B Units
Entity Registrant Name	'MARKWEST ENERGY PARTNERS L P	'	'
Entity Central Index Key	'0001166036	'	'
Document Type	'10-Q	'	'
Document Period End Date	30-Jun-14	'	'
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	'	177,021,464	11,972,634
Document Fiscal Year Focus	'2014	'	'
Document Fiscal Period Focus	'Q2	'	'

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents ($225,020 and $4,114, respectively)	$299,412	$85,305
Restricted cash	10,000	10,000
Receivables, net ($6,678 and $5,346, respectively)	306,101	299,107
Receivables from unconsolidated affiliates, net ($10,334 and $0, respectively)	13,977	'
Inventories ($6,838 and $2,553, respectively)	62,735	41,363
Fair value of derivative instruments	5,935	11,457
Deferred income taxes	13,575	23,200
Other current assets ($4,475 and $5,527, respectively)	34,700	44,068
Total current assets	746,435	514,500
Property, plant and equipment ($1,115,941 and $1,655,789, respectively)	8,798,039	8,583,767
Less: accumulated depreciation ($35,192 and $33,583, respectively)	-1,061,151	-890,598
Total property, plant and equipment, net	7,736,888	7,693,169
Other long-term assets:	'	'
Restricted cash	10,000	10,000
Investment in unconsolidated affiliates ($558,603 and $0, respectively)	629,927	75,627
Intangibles, net of accumulated amortization of $317,377 and $285,732, respectively	842,227	874,792
Goodwill	144,856	144,856
Deferred financing costs, net of accumulated amortization of $28,220 and $25,083, respectively	49,841	52,132
Deferred contract cost, ($0 and $6,591, respectively), net of accumulated amortization of $3,042 and $2,886 ($0), respectively	20,208	26,955
Fair value of derivative instruments	'	505
Other long-term assets ($5 and $658, respectively)	3,008	3,887
Total assets	10,183,390	9,396,423
Current liabilities:	'	'
Accounts payable ($26,094 and $82,007, respectively)	381,953	401,088
Accrued liabilities ($33,482 and $112,029, respectively)	338,588	437,847
Fair value of derivative instruments	21,930	28,838
Total current liabilities	742,471	867,773
Deferred income taxes	305,525	287,566
Fair value of derivative instruments	35,668	27,763
Long-term debt, net of discounts of $6,563 and $6,929, respectively	3,464,637	3,023,071
Other long-term liabilities	162,828	156,500
Commitments and contingencies (Note 11)	'	'
Redeemable non-controlling interest (Note 3)	70,711	235,617
Equity:	'	'
Non-controlling interest in consolidated subsidiaries	885,532	719,813
Total equity	5,401,550	4,798,133
Total liabilities and equity	10,183,390	9,396,423
Common Units	'	'
Equity:	'	'
Common units or Class B units	3,913,993	3,476,295
Total equity	3,913,993	3,476,295
Class B Units	'	'
Equity:	'	'
Common units or Class B units	602,025	602,025
Total equity	$602,025	$602,025

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Cash and cash equivalents	$299,412	$85,305
Receivables, net	306,101	299,107
Receivables from unconsolidated affiliate	13,977	'
Inventories	62,735	41,363
Other current assets	34,700	44,068
Property, plant and equipment	8,798,039	8,583,767
Accumulated depreciation	1,061,151	890,598
Investment in unconsolidated affiliates	629,927	75,627
Deferred contract cost	20,208	26,955
Accumulated amortization, deferred contract cost	3,042	2,886
Other long-term assets	3,008	3,887
Accounts payable	381,953	401,088
Accrued liabilities	338,588	437,847
Common Units	'	'
Common units issued (in units)	169,261	157,766
Common units outstanding (in units)	169,261	157,766
Class B Units	'	'
Common units issued (in units)	15,964	15,964
Common units outstanding (in units)	15,964	15,964
Total Variable Interest Entities	'	'
Cash and cash equivalents	225,020	4,114
Receivables, net	6,678	5,346
Receivables from unconsolidated affiliate	10,334	0
Inventories	6,838	2,553
Other current assets	4,475	5,527
Property, plant and equipment	1,115,941	1,655,789
Accumulated depreciation	35,192	33,583
Investment in unconsolidated affiliates	558,603	0
Accumulated amortization, intangibles	317,377	285,732
Accumulated amortization, deferred financing costs	28,220	25,083
Deferred contract cost	0	6,591
Accumulated amortization, deferred contract cost	0	0
Other long-term assets	5	658
Accounts payable	26,094	82,007
Accrued liabilities	33,482	112,029
Long-term debt, discounts	$6,563	$6,929

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Operations (USD $)	3 Months Ended		6 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Revenue:	'	'	'	'
Revenue	$525,119	$395,421	$1,041,562	$768,879
Derivative (loss) gain	-6,753	19,699	-10,720	19,514
Total revenue	518,366	415,120	1,030,842	788,393
Operating expenses:	'	'	'	'
Purchased product costs	215,824	155,359	427,388	307,916
Derivative loss (gain) related to purchased product costs	11,964	-20,432	4,166	-31,136
Facility expenses	83,545	62,797	167,250	122,307
Derivative loss related to facility expenses	2,045	800	1,777	468
Selling, general and administrative expenses	27,701	25,499	62,991	50,741
Depreciation	104,078	71,562	206,007	139,579
Amortization of intangible assets	15,965	17,092	31,943	31,922
Loss (gain) on disposal of property, plant and equipment	1,450	-37,736	1,357	-37,598
Accretion of asset retirement obligations	168	157	336	509
Total operating expenses	462,740	275,098	903,215	584,708
Income from operations	55,626	140,022	127,627	203,685
Other income (expense):	'	'	'	'
Equity in (loss) earnings from unconsolidated affiliates	-721	430	-471	665
Interest income	10	62	19	211
Interest expense	-43,391	-36,955	-84,375	-75,291
Amortization of deferred financing costs and debt discount (a component of interest expense)	-1,449	-1,784	-4,273	-3,614
Loss on redemption of debt	'	'	'	-38,455
Miscellaneous income, net	33	6	43	6
Income before provision for income tax	10,108	101,781	38,570	87,207
Provision for income tax expense (benefit):	'	'	'	'
Current	-19	-2,745	326	-8,159
Deferred	-2,921	19,028	9,280	30,999
Total provision for income tax	-2,940	16,283	9,606	22,840
Net income	13,048	85,498	28,964	64,367
Net (income) loss attributable to non-controlling interest	-4,071	-1,799	-7,495	3,874
Net income attributable to the Partnership's unitholders	$8,977	$83,699	$21,469	$68,241
Net income attributable to the Partnership's common unitholders per common unit:	'	'	'	'
Basic (in dollars per unit)	$0.05	$0.63	$0.13	$0.52
Diluted (in dollars per unit)	$0.05	$0.55	$0.12	$0.45
Weighted average number of outstanding common units:	'	'	'	'
Basic (in units)	164,613	131,227	161,727	129,928
Diluted (in units)	181,237	151,866	178,378	150,580
Cash distribution declared per common unit (in dollars per unit)	$0.87	$0.83	$1.73	$1.65

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Changes in Equity (USD $)	Total	Common Units	Class B Units	Non-controlling Interest	Redeemable Non-controlling Interest (Temporary Equity)
In Thousands, unless otherwise specified
Balance at Dec. 31, 2012	$3,111,398	$2,097,404	$752,531	$261,463	'
Balance (in units) at Dec. 31, 2012	'	127,494	19,954	'	'
Increase (Decrease) in Equity	'	'	'	'	'
Issuance of units in public offerings, net of offering costs	348,352	348,352	'	'	'
Issuance of units in public offerings, net of offering costs (in units)	'	5,720	'	'	'
Distributions paid	-215,015	-214,903	'	-112	'
Contributions from non-controlling interest	685,219	'	'	685,219	'
Redeemable non-controlling interest classified as temporary equity	-486,670	'	'	-486,670	486,670
Share-based compensation activity	2,092	2,092	'	'	'
Share-based compensation activity (in units)	'	161	'	'	'
Excess tax benefits related to share-based compensation	650	650	'	'	'
Deferred income tax impact from changes in equity	-28,077	-28,077	'	'	'
Net income	64,367	68,241	'	-3,874	'
Balance at Jun. 30, 2013	486,670	'	'	'	486,670
Balance at Jun. 30, 2013	3,482,316	2,273,759	752,531	456,026	'
Balance (in units) at Jun. 30, 2013	'	133,375	19,954	'	'
Balance at Dec. 31, 2013	235,617	'	'	'	235,617
Balance at Dec. 31, 2013	4,798,133	3,476,295	602,025	719,813	'
Balance (in units) at Dec. 31, 2013	'	157,766	15,964	'	'
Increase (Decrease) in Equity	'	'	'	'	'
Issuance of units in public offerings, net of offering costs	711,837	711,837	'	'	'
Issuance of units in public offerings, net of offering costs (in units)	'	11,284	'	'	'
Distributions paid	-278,406	-278,316	'	-90	'
Redeemable non-controlling interest classified as temporary equity	164,906	'	'	164,906	-164,906
Elimination of non-controlling interest from deconsolidation of a subsidiary	-6,592	'	'	-6,592	'
Share-based compensation activity	1,012	1,012	'	'	'
Share-based compensation activity (in units)	'	211	'	'	'
Deferred income tax impact from changes in equity	-18,304	-18,304	'	'	'
Net income	28,964	21,469	'	7,495	'
Balance at Jun. 30, 2014	70,711	'	'	'	70,711
Balance at Jun. 30, 2014	$5,401,550	$3,913,993	$602,025	$885,532	'
Balance (in units) at Jun. 30, 2014	'	169,261	15,964	'	'

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Cash Flows (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
Cash flows from operating activities:	'	'
Net income	$28,964	$64,367
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation	206,007	139,579
Amortization of intangible assets	31,943	31,922
Loss on redemption of debt	'	38,455
Amortization of deferred financing costs and debt discount	4,273	3,614
Accretion of asset retirement obligations	336	509
Amortization of deferred contract cost	1,025	156
Phantom unit compensation expense	9,955	7,298
Equity in loss (earnings) from unconsolidated affiliates	471	-665
Distributions from unconsolidated affiliates	3,910	2,728
Unrealized loss (gain) on derivative instruments	7,024	-46,320
Loss (gain) on disposal of property, plant and equipment	1,357	-37,598
Deferred income taxes	9,280	30,999
Changes in operating assets and liabilities, net of deconsolidation:	'	'
Receivables	-32,291	-34,529
Receivables from unconsolidated affiliate	2,768	'
Inventories	-21,435	-11,828
Other current assets	7,434	607
Accounts payable and accrued liabilities	87,371	-7,462
Other long-term assets	761	-21,751
Other long-term liabilities	7,670	17,515
Net cash provided by operating activities	356,823	177,596
Cash flows from investing activities:	'	'
Restricted cash	'	25,500
Capital expenditures	-1,275,323	-1,435,084
Investment in unconsolidated affiliates	-76,054	-8,336
Proceeds from sale of equity interest in unconsolidated affiliate	324,657	'
Acquisition of business, net of cash acquired	'	-225,210
Proceeds from disposal of property, plant and equipment	21,562	208,109
Net cash flows used in investing activities	-1,005,158	-1,435,021
Cash flows from financing activities:	'	'
Proceeds from public equity offerings, net	711,837	348,352
Proceeds from Credit Facility	1,923,500	'
Payments of Credit Facility	-1,482,300	'
Proceeds from long-term debt	'	1,000,000
Payments of long-term debt	'	-501,112
Payments of premiums on redemption of long-term debt	'	-31,516
Payments for debt issuance costs, deferred financing costs and registration costs	-2,045	-14,046
Contributions from non-controlling interest	'	685,219
Payments of SMR liability	-1,201	-1,103
Cash paid for taxes related to net settlement of share-based payment awards	-8,943	-5,206
Excess tax benefits related to share-based compensation	'	650
Payment of distributions to common unitholders	-278,316	-214,903
Payment of distributions to non-controlling interest	-90	-112
Net cash flows provided by financing activities	862,442	1,266,223
Net increase in cash and cash equivalents	214,107	8,798
Cash and cash equivalents at beginning of year	85,305	345,756
Cash and cash equivalents at end of period	$299,412	$354,554

Organization_and_Basis_of_Pres

Organization and Basis of Presentation	6 Months Ended
	Jun. 30, 2014
Organization and Basis of Presentation	'
Organization and Basis of Presentation	'
	1. Organization and Basis of Presentation
	MarkWest Energy Partners, L.P. was formed in 2002 as a Delaware limited partnership. The Partnership is engaged in the gathering, processing and transportation of natural gas; the gathering, transportation, fractionation, storage and marketing of NGLs; and the gathering and transportation of crude oil. The Partnership has a leading presence in many unconventional gas plays including the Marcellus Shale, Utica Shale, Huron/Berea Shale, Haynesville Shale, Woodford Shale and Granite Wash formations.
	These unaudited condensed consolidated financial statements have been prepared in accordance with the rules and regulations of the SEC for interim financial reporting. Accordingly, certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted. These condensed consolidated financial statements should be read in conjunction with the Partnership’s consolidated financial statements included in the Partnership’s Annual Report on Form 10-K for the year ended December 31, 2013. In management’s opinion, the Partnership has made all adjustments necessary for a fair presentation of its results of operations, financial position and cash flows for the periods shown. These adjustments are of a normal recurring nature.  Finally, results for the six months ended June 30, 2014 are not necessarily indicative of results for the full year 2014 or any other future period.
	The Partnership’s unaudited condensed consolidated financial statements include all majority-owned or controlled subsidiaries. In addition, MarkWest Utica EMG, L.L.C. (“MarkWest Utica EMG”), a VIE for which the Partnership has been determined to be the primary beneficiary, is included in the condensed consolidated financial statements (See Note 3). All intercompany investments, accounts and transactions have been eliminated. The Partnership’s investments in MarkWest Pioneer, L.L.C. (“MarkWest Pioneer”), Ohio Gathering Company L.L.C. (“Ohio Gathering”) and Centrahoma Processing, LLC (“Centrahoma”), in which the Partnership exercises significant influence but does not control and is not the primary beneficiary, are accounted for using the equity method.

Recent_Accounting_Pronouncemen

Recent Accounting Pronouncements	6 Months Ended
	Jun. 30, 2014
Recent Accounting Pronouncements	'
Recent Accounting Pronouncements	'
	2.  Recent Accounting Pronouncements
	In April 2014, the FASB issued ASU 2014-08 —Presentation Of Financial Statements (Topic 205) And Property, Plant, and Equipment (Topic 360): Reporting Discontinued Operations And Disclosures Of Disposals Of Components Of An Entity (“ASU 2014-08”) that will supersede previous GAAP for accounting for discontinued operations.  ASU 2014-08 raises the threshold for a disposal to qualify as a discontinued operation and requires new disclosures of both discontinued operations and certain other disposals that do not meet the definition of a discontinued operation.  ASU 2014-08 is effective for the Partnership prospectively as of January 1, 2015; however the Partnership has elected to early adopt the guidance as of April 1, 2014.  The adoption of the guidance did not have a material effect on the Partnership’s condensed consolidated financial statements.
	In May 2014, the FASB issued ASU 2014-09 — Revenue from Contracts with Customers (“ASU 2014-09”) that will supersede current revenue recognition guidance.  ASU 2014-09 is intended to provide companies with a single comprehensive model to use for all revenue arising from contracts with customers, which would include real estate sales transactions.  ASU 2014-09 is effective for the Partnership as of January 1, 2017 and must be adopted using either a full retrospective approach for all periods presented in the period of adoption (with some limited relief provided) or a modified retrospective approach.  The Partnership is in the early stages of evaluating ASU 2014-09 and has not yet determined the impact on the Partnership’s condensed consolidated financial statements.

Variable_Interest_Entity

Variable Interest Entity	6 Months Ended
	Jun. 30, 2014
Variable Interest Entity	'
Variable Interest Entity	'
	3.  Variable Interest Entity
	MarkWest Utica EMG
	Effective January 1, 2012, the Partnership and EMG Utica, LLC (“EMG Utica”) (together the “Members”), executed agreements to form a joint venture, MarkWest Utica EMG, to develop significant natural gas gathering, processing and NGL fractionation, transportation and marketing infrastructure in eastern Ohio.
	In February 2013, the Members entered into the Amended and Restated Limited Liability Company Agreement of MarkWest Utica EMG (“Amended Utica LLC Agreement”) which replaced the original agreement. Pursuant to the Amended Utica LLC Agreement, the aggregate funding commitment of EMG Utica increased to $950.0 million (the “Minimum EMG Investment”).  EMG Utica was required to fund all capital until the Minimum EMG Investment was satisfied, which occurred in May 2013. As EMG Utica has funded the Minimum EMG Investment, the Partnership is required to fund, as needed, 100% of future capital for MarkWest Utica EMG until such time as the aggregate capital that has been contributed by the Members equals $2.0 billion. After such time, and until such time as the investment balances of the Partnership and EMG Utica are in the ratio of 70% and 30%, respectively (such time being referred to as the “Second Equalization Date”), EMG Utica will have the right, but not the obligation, to fund up to 10% of each capital call for MarkWest Utica EMG, and the Partnership will be required to fund all remaining capital not elected to be funded by EMG Utica. After the Second Equalization Date, the Partnership and EMG Utica will have the right, but not the obligation, to fund their pro rata portion (based on the respective investment balances) of any additional required capital and may also fund additional capital that the other party elects not to fund. As of June 30, 2014, EMG Utica has contributed $950.0 million and the Partnership has contributed approximately $944.1 million to MarkWest Utica EMG.
	Under the Amended Utica LLC Agreement, after EMG Utica has contributed more than $500.0 million to MarkWest Utica EMG and prior to December 31, 2016, EMG Utica’s investment balance will also be increased by a quarterly special non-cash allocation of income (“Preference Amount”) that is based upon the amount of capital contributed by EMG Utica in excess of $500.0 million. No Preference Amount will accrue to EMG Utica’s investment balance after December 31, 2016. EMG Utica received a special non-cash allocation of income of approximately $9.1 million and approximately $17.9 million for the three and six months ended June 30, 2014, respectively.
	If the Partnership’s investment balance does not equal at least 51% of the aggregate investment balances of both Members as of December 31, 2016, then EMG Utica may require the Partnership to purchase membership interests from EMG Utica so that, following the purchase, the Partnership’s investment balance equals 51% of the aggregate investment balances of the Members. The purchase price payable would equal the investment balance associated with the membership interests acquired from EMG Utica. If EMG Utica makes this election, the Partnership would be required to purchase the membership interests on or before March 1, 2017, but effective as of January 1, 2017. The amount of non-controlling interest subject to the redemption option as of June 30, 2014 is reported as Redeemable non-controlling interest in the mezzanine equity section of the Partnership’s Condensed Consolidated Balance Sheets.
	Under the Amended Utica LLC Agreement, the Partnership will continue to receive 60% of cash generated by MarkWest Utica EMG that is available for distribution until the earlier of December 31, 2016 and the date on which the Partnership’s investment balance equals 60% of the aggregate investment balances of the Partnership and EMG Utica. After the earlier of those dates, cash generated by MarkWest Utica EMG that is available for distribution will be allocated to the Partnership and EMG Utica in proportion to their respective investment balances.
	The Partnership has determined that MarkWest Utica EMG is a VIE primarily due to MarkWest Utica EMG’s inability to fund its planned activities without additional subordinated financial support. The Partnership has concluded that it is the primary beneficiary of MarkWest Utica EMG. As the primary beneficiary of MarkWest Utica EMG, the Partnership consolidates the entity and recognizes non-controlling interest and redeemable non-controlling interest. The decision to consolidate MarkWest Utica EMG is re-evaluated quarterly and is subject to change.
	The assets of MarkWest Utica EMG are the property of MarkWest Utica EMG and are not available to the Partnership for any other purpose, including as collateral for its secured debt (see Notes 9 and 15). MarkWest Utica EMG’s asset balances can only be used to settle its own obligations. The liabilities of MarkWest Utica EMG do not represent additional claims against the Partnership’s general assets and the creditors or beneficial interest holders of MarkWest Utica EMG do not have recourse to the general credit of the Partnership. The Partnership’s maximum exposure to loss as a result of its involvement with MarkWest Utica EMG includes its equity investment, any additional capital contribution commitments and any operating expenses incurred by the subsidiary operator in excess of its compensation received for the performance of the operating services. Other than temporary funding due to the timing of the administrative process associated with capital calls in the beginning of 2013, the Partnership did not provide any financial support to MarkWest Utica EMG that it was not contractually obligated to provide during the six months ended June 30, 2014 and 2013.
	Ohio Gathering
	Ohio Gathering is a subsidiary of MarkWest Utica EMG and is engaged in providing natural gas gathering services in the Utica Shale in eastern Ohio. Prior to June 1, 2014, MarkWest Utica EMG, as the primary beneficiary of a VIE, consolidated Ohio Gathering.  Effective June 1, 2014 (“Summit Investment Date”), Summit Midstream Partners (“Summit”) exercised its option (“Ohio Gathering Option”) and increased its equity ownership (“Summit Equity Ownership”) from less than 1% to approximately 40% through a cash investment of approximately $324.7 million that Ohio Gathering received on May 30, 2014 and a true-up payment of approximately $16.5 million that was contributed in July 2014.  MarkWest Utica EMG received $319.6 million as a distribution from Ohio Gathering as a result of the exercise of the Ohio Gathering Option.  Summit purchased its initial 1% equity interest and the Ohio Gathering Option from Blackhawk Midstream LLC (“Blackhawk”) in January 2014.  As of the Summit Investment Date, MarkWest Utica EMG was no longer deemed the primary beneficiary due to Summit’s voting rights on significant operating matters obtained as a result of its increased equity ownership in Ohio Gathering. As of the Summit Investment Date, the Partnership accounted for Ohio Gathering as an equity method investment as the Partnership exercises significant influence.  As of June 30, 2014, Ohio Gathering’s net assets are reported under the caption Investment in unconsolidated affiliates on the Condensed Consolidated Balance Sheet.
	The Partnership accounted for the increase in Summit’s Equity Ownership and the deconsolidation of Ohio Gathering as a partial sale of in-substance real estate.  In conjunction with Summit exercising the Ohio Gathering Option, Summit reimbursed MarkWest Utica EMG $5.0 million and an additional $0.3 million in July 2014 related to a reimbursement of certain costs incurred on behalf of Ohio Gathering and payable to the Partnership.  The Partnership accounted for the cash received of $5.3 million as a (Gain) loss on disposal of property, plant and equipment in the Partnership’s Condensed Consolidated Statement of Operations for the three and six months ended June 30, 2014.
	For the three and six months ended June 30, 2014, the Partnership’s condensed consolidated results of operations include the consolidated results of operations of Ohio Gathering through May 31, 2014.  For the month of June 2014, MarkWest Utica EMG has reported its pro rata share of Ohio Gathering’s net loss under the caption Equity in (loss) earnings of unconsolidated affiliate on the Condensed Consolidated Statements of Operations for the three and six months ended June 30, 2014.  Ohio Gathering is considered to be a related party.  The Partnership receives engineering and construction and administrative management fee revenues (“Management Fees”) for operating Ohio Gathering.  The June 30, 2014 receivable balance related to Ohio Gathering’s management and operational fees was $14.0 million and is reported as Receivables from unconsolidated affiliates, net in the current asset section of the Partnership’s Condensed Consolidated Balance Sheets.  The amount of Management Fees revenue related to Ohio Gathering for the three and six months ended June 30, 2014 was approximately $1.0 million and is reported as Revenue in the Condensed Consolidated Statement of Operations.

Other_Equity_Interests

Other Equity Interests	6 Months Ended
	Jun. 30, 2014
Other Equity Interests	'
Other Equity Interests	'
	4. Other Equity Interests
	MarkWest Utica EMG Condensate
	In December 2013, the Partnership and The Energy & Minerals Group (“EMG”) (together the “Condensate Members”) executed an agreement (“Utica Condensate LLC Agreement”) to form MarkWest Utica EMG Condensate, L.L.C. (“Utica Condensate”) for the purpose of engaging in wellhead condensate gathering, stabilization, terminalling, storage and marketing in the state of Ohio.
	Under the terms of the Utica Condensate LLC Agreement, until the Condensate Equalization Date (as defined below) the Partnership has a 55% equity ownership interest and EMG has a 45% equity ownership interest in Utica Condensate. After the Condensate Equalization Date, each Condensate Member’s equity ownership interest will be equal to its investment balance expressed as a percentage of the aggregate investment balance of all Condensate Members. However, both before and after the Condensate Equalization Date, allocations of profits and losses and distributions of available cash will be made to the Condensate Members based upon the investment balances of the Condensate Members. The investment balances of the Condensate Members are subject to reduction if, and to the extent, that the Condensate Members receive distributions of available cash prior to the Condensate Equalization Date as a result of the exercise of the Ohio Condensate Option by Summit as defined below. EMG is required to provide 100% of the capital funding to Utica Condensate until the earlier of 1) such time that EMG has contributed $100.0 million (“Tier 1 Condensate Contributions”) or 2) September 1, 2014. If EMG completes the Tier 1 Condensate Contributions prior to September 1, 2014, the Partnership is required to contribute 100% of the required capital until the earlier of 1) September 1, 2014, 2) such time as the total capital contributed equals $125.0 million (the earlier of the two foregoing dates, the “Required Condensate True Up Date”) and 3) the date on which the Partnership has an investment balance equal to 55% of the aggregate investment balances of the Condensate Members (the earlier of the three foregoing dates, the “Condensate Equalization Date”). If the Partnership’s investment balance in Utica Condensate does not equal 55% of the total investment balances of the Condensate Members as of the Required Condensate True Up Date, the Partnership is required to purchase ownership interests from EMG such that, following the purchase, the Partnership’s investment balance associated with its ownership interest will equal 55% (“Required True Up Transaction”). The purchase price payable would equal the investment balance associated with the ownership interests so acquired from EMG. If Utica Condensate requires additional capital subsequent to the Condensate Equalization Date, each member has the right, but not the obligation, to contribute capital in proportion to its ownership interest.
	Under the Utica Condensate LLC Agreement, oversight of the business and affairs of Utica Condensate will be managed by a board of managers. Prior to the Condensate Equalization Date, the board of managers will consist of three managers designated by the Partnership and three managers designated by EMG. Thereafter, the number of managers that each Condensate Member may designate will be determined based upon ownership interests. In addition, both the Partnership and EMG have consent rights with respect to certain specified material transactions involving Utica Condensate; therefore, management has concluded that Utica Condensate is under joint control and will be accounted for as an equity method investment.
	Ohio Condensate
	Initially, Utica Condensate’s business will be conducted solely through its subsidiary, Ohio Condensate Company L.L.C. (“Ohio Condensate”), which was formed in December 2013 through an agreement executed between Utica Condensate and Blackhawk (“Ohio Condensate LLC Agreement”), in which Utica Condensate and Blackhawk contributed cash in exchange for equity ownership interests of 99% and 1%, respectively. In January 2014, Summit purchased Blackhawk’s 1% equity interest and its option to purchase up to an additional equity ownership interest of 40% in Ohio Condensate (“Ohio Condensate Option”).  Effective as of the Summit Investment Date, Summit exercised the Ohio Condensate Option and increased its equity ownership from less than 1% to approximately 40% through a cash investment of approximately $7.3 million, subject to a true-up of approximately $1.3 million that was contributed by Summit in July 2014.
	As of June 30, 2014, Utica Condensate owned 60% of Ohio Condensate.  The Partnership sold approximately $17 million of assets under construction to Utica Condensate in December 2013 and recorded that amount in Receivables, net in the accompanying Condensed Consolidated Balance Sheets as of December 31, 2013. The Partnership received the $17 million in the first quarter of 2014 and has recorded the proceeds in the Proceeds from disposal of property, plant and equipment in the accompanying Condensed Consolidated Statement of Cash Flows for the six months ended June 30, 2014.  The amount of Management Fees revenue related to Ohio Condensate for the three and six months ended June 30, 2014 was approximately $0.9 million and $1.3 million, respectively, and is reported as Revenue in the Condensed Consolidated Statement of Operations.

Business_Combinations

Business Combinations	6 Months Ended
	Jun. 30, 2014
Business Combination	'
Business Combination	'
	5.  Business Combination
	Buffalo Creek Acquisition
	On May 8, 2013, the Partnership acquired natural gas gathering and processing assets from Chesapeake Energy Corporation (“Chesapeake”) for a cash purchase price of approximately $225.2 million. The acquired assets include a 200 MMcf/d cryogenic gas processing plant under construction (which commenced operation in February 2014), known as the Buffalo Creek Plant, 22 miles of gas gathering pipeline in Hemphill County, Texas and approximately 30 miles of rights-of-way associated with the future construction of a trunk line. Additional assets acquired from Chesapeake consist of an amine treating facility and a five-mile gas gathering pipeline in Washita County, Oklahoma. This acquisition is referred to as the “Buffalo Creek Acquisition.”
	Concurrently with the closing of the Buffalo Creek Acquisition, the Partnership entered into a long-term fee-based agreement to provide treating, processing and certain gathering and compression services for natural gas owned or controlled by Chesapeake at the acquired facilities. Chesapeake has dedicated 130,000 acres throughout the Anadarko Basin to the Partnership as part of this long-term agreement. As a result of the acquisition, the Partnership has expanded its presence in the Granite Wash and Hogshooter formations in Oklahoma.
	Contemporaneously with the Buffalo Creek Acquisition, Chesapeake agreed to extend a keep-whole processing agreement for natural gas produced in the Appalachia Basin area of the Partnership’s Northeast segment for five additional years, to 2020. The Partnership paid an additional $20.0 million of cash upon closing the Buffalo Creek Acquisition as consideration for the extension and has recorded it as Deferred contract cost in the accompanying Consolidated Balance Sheets. The deferred contract cost is being amortized over the extension term. This $20.0 million is not considered to be part of the purchase price of the Buffalo Creek Acquisition and is not included in the purchase price allocation table below.
	The goodwill recognized from the Buffalo Creek Acquisition results primarily from the Partnership’s ability to grow its business in the liquids-rich gas areas of the Granite Wash and Hogshooter formations in Oklahoma and access additional markets in a competitive environment as a result of securing the gathering and processing rights for a large area of dedicated acreage. All of the goodwill is deductible for tax purposes.
	The following table summarizes the purchase price allocation for the Buffalo Creek Acquisition (in thousands):
	Assets:
	Property, plant and equipment	144,115
	Goodwill	2,682
	Intangible asset	84,500
	Liabilities:
	Accounts payable	(6,087		)
	Total	$	225,210

Derivative_Financial_Instrumen

Derivative Financial Instruments	6 Months Ended
	Jun. 30, 2014
Derivative Financial Instruments	'
Derivative Financial Instruments	'
	6.  Derivative Financial Instruments
	Commodity Derivatives
	NGL and natural gas prices are volatile and are impacted by changes in fundamental supply and demand, as well as market uncertainty, availability of NGL transportation and fractionation capacity and market outlets, and a variety of additional factors that are beyond the Partnership’s control. The Partnership’s profitability is directly affected by prevailing commodity prices primarily as a result of processing or conditioning at its own or third-party processing plants, purchasing and selling or gathering and transporting volumes of natural gas at index-related prices and the cost of third-party transportation and fractionation services. To the extent that commodity prices influence the level of natural gas drilling by the Partnership’s producer customers, such prices also affect profitability. To protect itself financially against adverse price movements and to maintain more stable and predictable cash flows so that the Partnership can meet its cash distribution objectives, debt service and capital plans, the Partnership executes a strategy governed by the risk management policy approved by the General Partner’s board of directors. The Partnership has a committee comprised of senior management that oversees risk management activities, continually monitors the risk management program and adjusts its strategy as conditions warrant. The Partnership enters into certain derivative contracts to reduce the risks associated with unfavorable changes in the prices of natural gas, NGLs and crude oil. Derivative contracts utilized are swaps and options traded on the OTC market and fixed price forward contracts. The risk management policy does not allow the Partnership to take speculative positions with its derivative contracts.
	To mitigate its cash flow exposure to fluctuations in the price of NGLs, the Partnership has entered into derivative financial instruments relating to the future prices of NGLs and crude oil. The Partnership currently manages the majority of its NGL price risk using direct product NGL derivative contracts. The Partnership enters into NGL derivative contracts when adequate market liquidity exists and future prices are satisfactory. A portion of the Partnership’s NGL price exposure is managed by using crude oil contracts that were primarily executed when there was a strong relationship between changes in NGL and crude oil prices. In periods where NGL prices and crude oil prices are not consistent with the historical relationship, the crude oil contracts create increased risk and additional gains or losses. The Partnership may settle its crude oil contracts prior to the contractual settlement date in order to take advantage of favorable terms and reduce the future exposure resulting from the less effective crude oil contracts.
	To mitigate its cash flow exposure to fluctuations in the price of natural gas, the Partnership primarily utilizes derivative financial instruments relating to the future price of natural gas and takes into account the partial offset of its long and short gas positions resulting from normal operating activities.
	As a result of its current derivative positions, the Partnership has mitigated a portion of its expected commodity price risk through the fourth quarter of 2015. The Partnership would be exposed to additional commodity risk in certain situations such as if producers under deliver or over deliver product or when processing facilities are operated in different recovery modes. In the event the Partnership has derivative positions in excess of the product delivered or expected to be delivered, the excess derivative positions may be terminated.
	Currently, all of the Partnership’s financial derivative positions are with financial institutions that are syndicated members of the Credit Facility (“syndicated bank group members”). Management conducts a standard credit review on counterparties to derivative contracts. There are no collateral requirements for derivative contracts among the Partnership and any syndicated bank group members. Specifically, the Partnership is not required to post collateral when it enters into derivative contracts with syndicated bank group members, as the syndicated bank group members have a collateral position in substantially all the wholly-owned assets of the Partnership other than MarkWest Liberty Midstream and its subsidiaries. A separate agreement with certain syndicated bank group members allows MarkWest Liberty Midstream to enter into derivative positions without posting cash collateral.  The Partnership uses standardized agreements that allow for offset of certain positive and negative exposures (“master netting arrangements”) in the event of default or other terminating events, including bankruptcy.
	The Partnership records derivative contracts at fair value in the Condensed Consolidated Balance Sheets and has not elected hedge accounting or the normal purchases and normal sales designation for its derivative contracts.  The Partnership’s accounting may cause volatility in the Condensed Consolidated Statements of Operations as the Partnership recognizes in current earnings all unrealized gains and losses from the changes in fair value of derivatives.
	As of June 30, 2014, the Partnership had the following outstanding commodity contracts that were entered into to manage cash flow risk associated with future sales of NGLs or future purchases of natural gas:
	Derivative contracts not designated as hedging instruments	Financial		Notional Quantity
		Position		(net)
	Crude Oil (bbl)	Short		935,540
	Natural Gas (MMBtu)	Long		1,581,160
	NGLs (gal)	Short		83,399,447
	Embedded Derivatives in Commodity Contracts
	The Partnership has a commodity contract with a producer in the Appalachia region that creates a floor on the frac spread for gas purchases of 9,000 Dth/d. The commodity contract is a component of a broader regional arrangement that also includes a keep-whole processing agreement. This contract is accounted for as an embedded derivative and is recorded at fair value. The changes in fair value of this commodity contract are based on the difference between the contractual and index pricing and are recorded in earnings through Derivative loss (gain) related to purchased product costs. In February 2011, the Partnership executed agreements with the producer to extend the commodity contract and the related processing agreement from June 30, 2015 to December 31, 2022 with the producer’s option to extend the agreement for successive five-year terms through December 31, 2032. As of June 30, 2014, the estimated fair value of this contract was a liability of $97.8 million and the recorded value was a liability of $44.3 million. The recorded liability does not include the inception fair value of the commodity contract related to the extended period from April 1, 2015 to December 31, 2022. In accordance with GAAP for non-option embedded derivatives, the fair value of this extended portion of the commodity contract at its inception of February 1, 2011 is deemed to be allocable to the host processing contract and therefore not recorded as a derivative liability. See the following table for a reconciliation of the liability recorded for the embedded derivative as of June 30, 2014 (in thousands):
	Fair value of commodity contract	$	97,838
	Inception value for period from April 1, 2015 to December 31, 2022	(53,507		)
	Derivative liability as of June 30, 2014	$	44,331
	The Partnership has a commodity contract that gives it an option to fix a component of the utilities cost to an index price on electricity at its plant location in the Southwest segment through the fourth quarter of 2014. Changes in the fair value of the derivative component of this contract are recorded in Derivative loss related to facility expenses. As of June 30, 2014, the estimated fair value of this contract was an asset of $1.5 million.
	Financial Statement Impact of Derivative Instruments
	There were no material changes to the Partnership’s policy regarding the accounting for these instruments as previously disclosed in the Partnership’s Annual Report on Form 10-K for the year ended December 31, 2013. The impact of the Partnership’s derivative instruments on its Condensed Consolidated Balance Sheets is summarized below (in thousands):
		Assets						Liabilities
	Derivative instruments not designated as hedging	Fair Value at			Fair Value at			Fair Value at			Fair Value at
	instruments and their balance sheet location	June 30,			December 31,			June 30,			December 31,
		2014			2013			2014			2013
	Commodity contracts(1)
	Fair value of derivative instruments — current	$	5,935		$	11,457		$	(21,930	)	$	(28,838	)
	Fair value of derivative instruments — long-term	—			505			(35,668		)	(27,763		)
	Total	$	5,935		$	11,962		$	(57,598	)	$	(56,601	)
	(1)     Includes Embedded Derivatives in Commodity Contracts as discussed above.
	Although certain derivative positions are subject to master netting agreements, the Partnership has elected not to offset any derivative assets and liabilities. The gross amounts in the table below equal the balances presented in the Condensed Consolidated Balance Sheets.  The table below summarizes the impact if the Partnership had elected to net its derivative positions that are subject to master netting arrangements (in thousands):
		Assets									Liabilities
	As of June 30, 2014	Gross			Gross			Net Amount			Gross			Gross		Net
		Amounts of			Amounts						Amounts of			Amounts		Amount
		Assets in the			Not Offset in						Liabilities in			Not Offset in
		Consolidated			the						the			the
		Balance			Consolidated						Consolidated			Consolidated
		Sheet			Balance						Balance			Balance
					Sheet						Sheet			Sheet
	Current
	Commodity contracts	$	4,435		$	(3,947	)	$	488		$	(12,045	)	$	3,947	$	(8,098	)
	Embedded derivatives in commodity contracts	1,500			—			1,500			(9,885		)	—		(9,885		)
	Total current derivative instruments	5,935			(3,947		)	1,988			(21,930		)	3,947		(17,983		)
	Non-current
	Commodity contracts	—			—			—			(1,222		)	—		(1,222		)
	Embedded derivatives in commodity contracts	—			—			—			(34,446		)	—		(34,446		)
	Total non-current derivative instruments	—			—			—			(35,668		)	—		(35,668		)
	Total derivative instruments	$	5,935		$	(3,947	)	$	1,988		$	(57,598	)	$	3,947	$	(53,651	)
		Assets									Liabilities
	As of December 31, 2013	Gross			Gross			Net Amount			Gross			Gross		Net
		Amounts of			Amounts						Amounts of			Amounts		Amount
		Assets in the			Not Offset in						Liabilities in			Not Offset in
		Consolidated			the						the			the
		Balance			Consolidated						Consolidated			Consolidated
		Sheet			Balance						Balance			Balance
					Sheet						Sheet			Sheet
	Current
	Commodity contracts	$	8,181		$	(7,017	)	$	1,164		$	(18,293	)	$	7,017	$	(11,276	)
	Embedded derivatives in commodity contracts	3,276			—			3,276			(10,545		)	—		(10,545		)
	Total current derivative instruments	11,457			(7,017		)	4,440			(28,838		)	7,017		(21,821		)
	Non-current
	Commodity contracts	505			—			505			—			—		—
Embedded derivatives in commodity contracts	—			—			—			(27,763		)	—		(27,763		)
Total non-current derivative instruments	505			—			505			(27,763		)	—		(27,763		)
Total derivative instruments	$	11,962		$	(7,017	)	$	4,945		$	(56,601	)	$	7,017	$	(49,584	)
In the tables above, the Partnership does not offset a counterparty’s current derivative contracts with the counterparty’s non-current derivative contracts, although the Partnership’s master netting arrangements would allow current and non-current positions to be offset in the event of default. Additionally, in the event of a default, the Partnership’s master netting arrangements would allow for the offsetting of all transactions executed under the master netting arrangement. These types of transactions may include non-derivative instruments, derivatives qualifying for scope exceptions, receivables and payables arising from settled positions, and other forms of non-cash collateral (such as letters of credit). These types of transactions are excluded from the offsetting tables presented above.
The impact of the Partnership’s derivative instruments on its Condensed Consolidated Statements of Operations is summarized below (in thousands):
Derivative contracts not designated as	Three months ended June 30,						Six months ended June 30,
hedging instruments and the location of
gain or (loss) recognized in income	2014			2013			2014			2013
Revenue: Derivative (loss) gain
Realized (loss) gain	$	(1,774	)	$	3,089		$	(9,381	)	$	6,987
Unrealized (loss) gain	(4,979		)	16,610			(1,339		)	12,527
Total revenue: derivative (loss) gain	(6,753		)	19,699			(10,720		)	19,514
Derivative (loss) gain related to purchased product costs
Realized loss	(144		)	(1,045		)	(258		)	(3,125		)
Unrealized (loss) gain	(11,820		)	21,477			(3,908		)	34,261
Total derivative (loss) gain related to purchase product costs	(11,964		)	20,432			(4,166		)	31,136
Derivative loss related to facility expenses
Unrealized loss	(2,045		)	(800		)	(1,777		)	(468		)
Total (loss) gain	$	(20,762	)	$	39,331		$	(16,663	)	$	50,182

Fair_Value

Fair Value	6 Months Ended
	Jun. 30, 2014
Fair Value	'
Fair Value	'
	7. Fair Value
	Fair value measurements and disclosures relate primarily to the Partnership’s derivative positions discussed in Note 6. Money market funds, which are included in cash and cash equivalents, are measured at fair value and are included in Level 1 measurements of the valuation hierarchy. The following table presents the derivative instruments carried at fair value as of June 30, 2014 and December 31, 2013 (in thousands):
	As of June 30, 2014	Assets			Liabilities
	Significant other observable inputs (Level 2)
	Commodity contracts	$	89		$	(6,829	)
	Significant unobservable inputs (Level 3)
	Commodity contracts	4,346			(6,438		)
	Embedded derivatives in commodity contracts	1,500			(44,331		)
	Total carrying value in Condensed Consolidated Balance Sheet	$	5,935		$	(57,598	)
	As of December 31, 2013	Assets			Liabilities
	Significant other observable inputs (Level 2)
	Commodity contracts	$	544		$	(4,691	)
	Significant unobservable inputs (Level 3)
	Commodity contracts	8,142			(13,602		)
	Embedded derivatives in commodity contracts	3,276			(38,308		)
	Total carrying value in Condensed Consolidated Balance Sheet	$	11,962		$	(56,601	)
	The following table provides additional information about the significant unobservable inputs used in the valuation of Level 3 instruments as of June 30, 2014. The market approach is used for valuation of all instruments.
	Level 3 Instrument	Balance		Unobservable Inputs		Value Range		Time Period
		Sheet
		Classification
	Commodity contracts	Assets		Forward propane prices (per gallon) (1)		$  1.06 - $1.09		Jul. 2014 - Dec. 2014
				Forward isobutane prices (per gallon) (1)		$  1.34 - $1.36		Jul. 2014 - Dec. 2014
				Forward normal butane prices (per gallon) (1)		$  1.26 - $1.31		Jul. 2014 - Dec. 2014
				Forward natural gasoline prices (per gallon) (1)		$  2.15 - $2.21		Jul. 2014 - Dec. 2014
				Crude option volatilities (%)		13.89% - 14.93%		Sep. 2014 - Dec. 2014
		Liabilities		Forward propane prices (per gallon) (1)		$  1.06 - $1.09		Jul. 2014 - Dec. 2014
				Forward isobutane prices (per gallon) (1)		$  1.34 - $1.36		Jul. 2014 - Dec. 2014
				Forward normal butane prices (per gallon) (1)		$  1.26 - $1.31		Jul. 2014 - Dec. 2014
				Forward natural gasoline prices (per gallon) (1)		$  2.15 - $2.21		Jul. 2014 - Dec. 2014
				Crude option volatilities (%)		8.24% - 17.99%		Jul. 2014 - Dec. 2014
	Embedded derivatives in commodity contracts	Asset		ERCOT Pricing (per MegaWatt Hour) (2)		$  36.16 - $52.42		Jul. 2014 - Dec. 2014
		Liabilities		Forward propane prices (per gallon) (1)		$  1.02 - $1.10		Jul. 2014 - Dec. 2022
				Forward isobutane prices (per gallon) (1)		$  1.27 - $1.38		Jul. 2014 - Dec. 2022
	Level 3 Instrument	Balance		Unobservable Inputs		Value Range		Time Period
		Sheet
		Classification
				Forward normal butane prices (per gallon) (1)		$  1.19 - $1.32		Jul. 2014 - Dec. 2022
				Forward natural gasoline prices (per gallon) (1)		$  1.80 - $2.21		Jul. 2014 - Dec. 2022
				Forward natural gas prices (per MMBtu) (3)		$  3.46 - $5.14		Jul. 2014 - Dec. 2022
				Probability of renewal (4)		0%
	(1)     NGL prices decrease over the respective period.
	(2)     The forward ERCOT prices utilized in the valuations are generally increasing over time with a seasonal spike in pricing in the summer months.
	(3)     Natural gas prices used in the valuations are generally at the lower end of the range in the early years and increase over time.
	(4)     The producer counterparty to the embedded derivative has the option to renew the gas purchase agreement and the related keep-whole processing agreement for two successive five year terms after 2022. The embedded gas purchase agreement cannot be renewed without the renewal of the related keep-whole processing agreement. Due to the significant number of years until the renewal options are exercisable and the high level of uncertainty regarding the counterparty’s future business strategy, the future commodity price environment and the future competitive environment for midstream services in the Appalachia area, management determined that a 0% probability of renewal is an appropriate assumption.
	Fair Value Sensitivity Related to Unobservable Inputs
	Commodity contracts (assets and liabilities) - For the Partnership’s commodity contracts, increases in forward NGL prices result in a decrease in the fair value of the derivative assets and an increase in the fair value of the derivative liabilities. The forward prices for the individual NGL products generally increase or decrease in a positive correlation with one another. An increase in crude option volatilities will generally result in an increase in the fair value of the Partnership’s derivative assets and derivative liabilities in commodity contracts.
	Embedded derivative in commodity contracts (liability) - The embedded derivative liability relates to the natural gas purchase agreement embedded in a keep-whole processing agreement as discussed further in Note 6. Increases (decreases) in forward NGL prices result in an increase (decrease) in the fair value of the embedded derivative liability. An increase in the probability of renewal would result in an increase in the fair value of the related embedded derivative liability.
	Embedded derivative in commodity contracts (asset) - The embedded derivative asset relates to utilities costs discussed further in Note 6. Increases in the forward ERCOT prices, relative to natural gas prices, result in an increase in the fair value of the embedded derivative asset.
	Level 3 Valuation Process
	The Partnership’s Risk Management Department (the “Risk Department”) reports to the Chief Financial Officer, is responsible for the valuation of the Partnership’s commodity derivative contracts and embedded derivatives in commodity contracts and is responsible for the oversight of the Partnership’s commodity risk management program. The members of the Risk Department have the requisite experience, knowledge and day-to-day involvement in the energy commodity markets to ensure appropriate valuations and understand the changes in the valuations from period to period. The valuations of the Level 3 commodity derivative contracts are performed by a third-party pricing service and reviewed and validated on a quarterly basis by the Risk Department by comparing the pricing and option volatilities to actual market data and/or data provided by at least one other independent third-party pricing service. The valuations for the embedded derivatives in commodity contracts are completed by the Risk Department utilizing the market data and price curves provided by the third-party pricing service. For the embedded derivative in the keep-whole processing arrangement discussed in Note 6, the Risk Department must develop forward price curves for NGLs and natural gas for periods in which price curves are not available from third-party pricing services due to insufficient market data. As of June 30, 2014, the Risk Department utilized internally developed price curves for the period of January 2015 through December 2022 in the valuation of the embedded derivative in the keep-whole processing arrangement. In developing the pricing curves for these periods, the Risk Department maximizes its use of the latest known market data and trends as well as its understanding of the historical relationships between forward NGL and natural gas prices and the forward market data that is available for the required period, such as crude oil pricing and natural gas pricing from other markets. However, there is very limited actual market data available to validate the Risk Department’s estimated price curves.
	Changes in Level 3 Fair Value Measurements
	The table below includes a roll forward of the balance sheet amounts for the three and six months ended June 30, 2014 and 2013 for net assets and liabilities classified by the Partnership within Level 3 of the valuation hierarchy (in thousands):
		Three months ended June 30, 2014
		Commodity Derivative			Embedded Derivatives
		Contracts (net)			in Commodity
					Contracts (net)
	Fair value at beginning of period	$	(751	)	$	(28,486	)
	Total loss (realized and unrealized) included in earnings (1)	(1,961		)	(16,479		)
	Settlements	620			2,134
	Fair value at end of period	$	(2,092	)	$	(42,831	)
	The amount of total losses for the period included in earnings attributable to the change in unrealized gains or losses relating to contracts still held at end of period (1)	$	(1,758	)	$	(15,959	)
		Three months ended June 30, 2013
		Commodity Derivative			Embedded Derivatives
Contracts (net)		in Commodity
		Contracts (net)
Fair value at beginning of period	$	12,477		$	(24,881	)
Total gain (realized and unrealized) included in earnings (1)	16,896			20,459
Settlements	(2,995		)	2,019
Fair value at end of period	$	26,378		$	(2,403	)
The amount of total losses for the period included in earnings attributable to the change in unrealized gains or losses relating to contracts still held at end of period (1)	$	14,755		$	20,766
	Six months ended June 30, 2014
	Commodity Derivative			Embedded Derivatives
	Contracts (net)			in Commodity
				Contracts (net)
Fair value at beginning of period	$	(5,460	)	$	(35,032	)
Total loss (realized and unrealized) included in earnings (1)	(4,238		)	(12,068		)
Settlements	7,606			4,269
Fair value at end of period	$	(2,092	)	$	(42,831	)
The amount of total losses for the period included in earnings attributable to the change in unrealized gains or losses relating to contracts still held at end of period (1)	$	(1,319	)	$	(12,204	)
	Six months ended June 30, 2013
	Commodity Derivative			Embedded Derivatives
	Contracts (net)			in Commodity
				Contracts (net)
Fair value at beginning of period	$	12,449		$	(33,957	)
Total gain (realized and unrealized) included in earnings (1)	20,220			26,991
Settlements	(6,291		)	4,563
Fair value at end of period	$	26,378		$	(2,403	)
The amount of total losses for the period included in earnings attributable to the change in unrealized gains or losses relating to contracts still held at end of period (1)	$	17,854		$	27,229
(1)                 Gains and losses on Commodity Derivative Contracts classified as Level 3 are recorded in Revenue: Derivative (loss) gain. Gains and losses on Embedded Derivatives in Commodity Contracts are recorded in Purchased product costs, Derivative loss (gain) related to purchased product costs, Facility expenses and Derivative loss related to facility expenses.

Inventories

Inventories	6 Months Ended
	Jun. 30, 2014
Inventories	'
Inventories	'
	8. Inventories
	Inventories consist of the following (in thousands):
		June 30, 2014		December 31, 2013
	NGLs	$	38,444	$	21,131
	Line fill	10,466		7,960
	Spare parts, materials and supplies	13,825		12,272
	Total inventories	$	62,735	$	41,363

LongTerm_Debt

Long-Term Debt	6 Months Ended
	Jun. 30, 2014
Long-Term Debt	'
Long-Term Debt	'
	9. Long-Term Debt
	Debt is summarized below (in thousands):
		June 30, 2014		December 31, 2013
	Credit Facility
	Credit Facility, variable interest, due March 2019 (1)	$	441,200	$	—
	Senior Notes (2)
	2020 Senior Notes, 6.75% interest, issued November 2010 and due November 2020	500,000		500,000
	2021 Senior Notes, 6.5% interest, net of discount of $444 and $474, respectively, issued February and March 2011 and due August 2021	324,556		324,526
	2022 Senior Notes, 6.25% interest, issued October 2011 and due June 2022	455,000		455,000
	2023A Senior Notes, 5.5% interest, net of discount of $6,119 and $6,455, respectively, issued August 2012 and due February 2023	743,881		743,545
	2023B Senior Notes, 4.5% interest, issued January 2013 and due July 2023	1,000,000		1,000,000
	Total long-term debt	$	3,464,637	$	3,023,071
	(1)     Applicable interest rate was 4.5% for $166.2 million and 2.4% for $275.0 million at June 30, 2014.  The carrying amount of the Credit Facility approximates fair value due to the short-term and variable nature of the borrowings.  The fair value of the Partnership’s Credit Facility is considered a Level 2 measurement.
	(2)     The estimated aggregate fair value of the senior notes (collectively, the “Senior Notes”) was approximately $3,217 million and $3,079 million as of June 30, 2014 and December 31, 2013, respectively, based on quoted prices in an inactive market. The fair value of the Partnership’s Senior Notes is considered a Level 3 measurement.
	Credit Facility
	On March 20, 2014, the Partnership amended the Credit Facility to increase total borrowing capacity to $1.3 billion, extend the maturity by approximately 18 months to March 20, 2019, amend the pricing terms (as discussed below), expand the existing accordion option from $250 million to $500 million and provide the Partnership with the right to release the collateral securing the Credit Facility.  The right to release collateral will occur once the Partnership’s long-term, senior unsecured debt (“Index Debt”) has received an investment grade rating from Standard & Poor’s equal to or more favorable than BBB- (stable) and from Moody’s equal to or more favorable than Baa3 (stable) and the Partnership’s Total Leverage Ratio (as defined in the Credit Facility) is not greater than 5.00 to 1.00 (“Collateral Release Date”). The Partnership incurred approximately $1.9 million of deferred financing costs associated with modifications of the Credit Facility during the six months ended June 30, 2014.
	The borrowings under the Credit Facility bear interest at a variable interest rate, plus basis points. The variable interest rate is based either on the London interbank market rate (“LIBO Rate Loans”) or the higher of (a) the prime rate set by the Credit Facility’s administrative agent, (b) the Federal Funds Rate plus 0.50% and (c) the rate for LIBO Rate Loans for a one month interest period plus 1% (“Alternate Base Rate Loans”). Prior to the Collateral Release Date, the basis points correspond to the Partnership’s Total Leverage Ratio, ranging from 0.5% to 1.5% for Alternate Base Rate Loans and from 1.5% to 2.5% for LIBO Rate Loans. After the Collateral Release Date, the basis points correspond to the credit rating for the Partnership’s Index Debt issued by Moody’s and Standard & Poor’s, ranging from 0.125% to 1% for Alternate Base Rate Loans and from 1.125% to 2% for LIBO Rate Loans.  The Partnership may utilize up to $150.0 million of the Credit Facility for the issuance of letters of credit and $10.0 million for shorter-term swingline loans.
	Under the provisions of the Credit Facility and indentures, the Partnership is subject to a number of restrictions and covenants. The Credit Facility and indentures place limits on the ability of the Partnership and its restricted subsidiaries to incur additional indebtedness; declare or pay dividends or distributions or redeem, repurchase or retire equity interests or subordinated indebtedness; make investments; incur liens; create any consensual limitation on the ability of the Partnership’s restricted subsidiaries to pay dividends or distributions, make loans or transfer property to the Partnership; engage in transactions with the Partnership’s affiliates; sell assets, including equity interests of the Partnership’s subsidiaries; make any payment on or with respect to or purchase, redeem, defease or otherwise acquire or retire for value any subordinated obligation or guarantor subordination obligation (except principal and interest at maturity); and consolidate, merge or transfer assets. The Credit Facility also limits the Partnership’s ability to enter into transactions with parties that require margin calls under certain derivative instruments. Under the Credit Facility, neither the Partnership nor the bank can require margin calls for outstanding derivative positions.
	Significant financial covenants under the Credit Facility include the Interest Coverage Ratio (as defined in the Credit Facility), which must be greater than 2.50 to 1.0 and the Total Leverage Ratio (as defined in the Credit Facility), which must be less than 5.5 to 1.0 prior to December 31, 2014, and thereafter until the Collateral Release Date the maximum permissible Total Leverage Ratio will be 5.25 to 1.0.  The Total Leverage Ratio at any fiscal quarter-end on or after the Collateral Release Date shall not be greater than 5.00 to 1.00.
	Under the provisions of the Credit Facility, the Partnership is subject to a number of restrictions and covenants. These covenants are used to calculate the available borrowing capacity on a quarterly basis. The Credit Facility is guaranteed by the Partnership’s 100% owned subsidiaries, other than MarkWest Liberty Midstream and its subsidiaries, and collateralized by substantially all of the Partnership’s assets and those of its 100% owned subsidiaries, other than MarkWest Liberty Midstream and its subsidiaries. As of June 30, 2014, the Partnership had $441.2 million borrowings outstanding and approximately $11.3 million of letters of credit outstanding under the Credit Facility, leaving approximately $847.5 million of unused capacity of which approximately $645 million was available for borrowing based on financial covenant requirements.  Additionally, the full amount of unused capacity is available for borrowing on a short term basis to provide financial flexibility within a given fiscal quarter.

Equity

Equity	6 Months Ended
	Jun. 30, 2014
Equity	'
Equity	'
	10. Equity
	Equity Offerings
	On September 5, 2013, the Partnership entered into an Equity Distribution Agreement with a financial institution (the “2013 Manager”) that established an At the Market offering program (the “September 2013 ATM”) pursuant to which the Partnership may sell from time to time through the 2013 Manager as its sales agent, common units representing limited partner interests having an aggregate offering price of up to $1 billion. During the six months ended June 30, 2014, the Partnership sold an aggregate of 4.2 million common units under the September 2013 ATM Agreement, receiving net proceeds of approximately $272 million after deducting approximately $3.5 million in manager fees and other third-party expenses.  The proceeds from sales were used to fund capital expenditures and for general Partnership purposes. The Partnership completed the September 2013 ATM on March 31, 2014.
	On March 11, 2014, the Partnership entered into an Equity Distribution Agreement with financial institutions (the “2014 Managers”) that established an At the Market offering program (the “March 2014 ATM”) pursuant to which the Partnership may sell from time to time through the 2014 Managers, as its sales agents, common units having an aggregate offering price of up to $1.2 billion.  During the six months ended June 30, 2014, the Partnership sold an aggregate of approximately 7.0 million common units under the March 2014 ATM Agreement, receiving net proceeds of approximately $440 million after deducting approximately $3.5 million in manager fees and other third-party expenses.  The proceeds from sales were used to fund capital expenditures and for general Partnership purposes.
	All of the Partnership’s Class B units were issued to and are held by M&R MWE Liberty, LLC, an affiliate of EMG, as part of the Partnership’s December 31, 2011 acquisition of the non-controlling interest in MarkWest Liberty Midstream & Resources, L.L.C. (“MarkWest Liberty Midstream”). Approximately four million Class B units converted to common units on July 1, 2014.  The remaining Class B units will convert to common units on a one-for-one basis in three equal installments beginning on July 1, 2015 and each of the next two anniversaries of such date.  After the units are converted to common units, M&R MWE Liberty, LLC may sell common units as part of the March 2014 ATM program.  These converted units will participate in the distributions declared on July 24, 2014.
	Distributions of Available Cash and Range of Unit Prices
		Common Unit Price				Distribution
						Per
						Common
	Quarter Ended	High		Low		Unit		Declaration Date	Record Date	Payment Date
	June 30, 2014	$	71.88	$	58.62	$	0.88	July 24, 2014	August 5, 2014	August 14, 2014
	March 31, 2014	$	73.42	$	61.6	$	0.87	April 22, 2014	May 7, 2014	May 15, 2014
	December 31, 2013	$	75.79	$	62.56	$	0.86	January 22, 2014	February 6, 2014	February 14, 2014

Commitments_and_Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2014
Commitments and Contingencies	'
Commitments and Contingencies	'
	11. Commitments and Contingencies
	Legal
	The Partnership is subject to a variety of risks and disputes and is a party to various legal proceedings in the normal course of its business. The Partnership maintains insurance policies in amounts and with coverage and deductibles that it believes are reasonable and prudent. However, the Partnership cannot assure that the insurance companies will promptly honor their policy obligations or that the coverage or levels of insurance will be adequate to protect the Partnership from all material expenses related to future claims for property loss or business interruption to the Partnership, or for third-party claims of personal injury and property damage, or that the coverages or levels of insurance it currently has will be available in the future at economical prices. While it is not possible to predict the outcome of the legal actions with certainty, management is of the opinion that appropriate provisions and accruals for potential losses associated with all legal actions have been made in the accompanying Condensed Consolidated Financial Statements and that none of these actions, either individually or in the aggregate, will have a material adverse effect on the Partnership’s financial condition, liquidity or results of operations.
	Contract Contingencies
	Certain natural gas processing and gathering arrangements require the Partnership to construct new natural gas processing plants and NGL pipelines and contain certain fees and concessions if specified construction milestones are not achieved for reasons other than force majeure. In certain cases, certain producers may have the right to cancel the processing arrangements if there are significant delays that are not due to force majeure. As of June 30, 2014, management does not believe there are any indications that the Partnership will not be able to meet the construction milestones or that force majeure does not apply or that such fees or concessions will otherwise apply.

Income_Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2014
Income Taxes	'
Income Taxes	'
	12. Income Taxes
	A reconciliation of the provision for income tax and the amount computed by applying the federal statutory rate to income before provision for income tax for the six months ended June 30, 2014 and 2013 is as follows (in thousands):
		Six months ended June 30, 2014
		Corporation			Partnership			Eliminations			Consolidated
	Income before provision for income tax	$	6,641		$	32,297		$	(368	)	$	38,570
	Federal statutory rate	35		%	0		%	0		%
	Federal income tax at statutory rate	2,324			—			—			2,324
	Permanent items	33			—			—			33
	State income taxes net of federal benefit	168			409			—			577
	Federal and state tax rate change	4,250			—			—			4,250
	Provision on income from Class A units (1)	2,422			—			—			2,422
	Provision for income tax	$	9,197		$	409		$	—		$	9,606
		Six months ended June 30, 2013
		Corporation			Partnership			Eliminations			Consolidated
	Income before provision for income tax	$	52,839		$	40,023		$	(5,655	)	$	87,207
	Federal statutory rate	35		%	0		%	0		%
	Federal income tax at statutory rate	18,494			—			—			18,494
	Permanent items	29			—			—			29
	State income taxes net of federal benefit	1,321			161			—			1,482
	Provision on income from Class A units (1)	2,835			—			—			2,835
	Provision for income tax	$	22,679		$	161		$	—		$	22,840
	(1)     The Corporation and the General Partner of the Partnership own Class A units of the Partnership that were received in the merger of the Corporation and the Partnership completed in February 2008. The Class A units share, on a pro-rata basis, in the income or loss of the Partnership, except for items attributable to the Partnership’s ownership of or sale of shares of the Corporation’s common stock. The provision for income tax on income from Class A units includes intra period allocations to continued operations and excludes allocations to equity.

Earnings_Per_Common_Unit

Earnings Per Common Unit	6 Months Ended
	Jun. 30, 2014
Earnings Per Common Unit	'
Earnings Per Common Unit	'
	13. Earnings Per Common Unit
	The following table shows the computation of basic and diluted net income per common unit for the three and six months ended June 30, 2014 and 2013, and the weighted-average units used to compute basic and diluted net income per common unit (in thousands, except per unit data):
		Three months ended June 30,				Six months ended June 30,
		2014		2013		2014		2013
	Net income attributable to the Partnership’s unitholders	$	8,977	$	83,699	$	21,469	$	68,241
	Less: Income allocable to phantom units	551		554		1,096		1,100
	Income available for common unitholders - basic	8,426		83,145		20,373		67,141
	Add: Income allocable to phantom units and DER expense	574		569		1,141		1,135
	Income available for common unitholders - diluted	$	9,000	$	83,714	$	21,514	$	68,276
	Weighted average common units outstanding - basic	164,613		131,227		161,727		129,928
	Potential common shares (Class B and phantom units)	16,624		20,639		16,651		20,652
	Weighted average common units outstanding - diluted	181,237		151,866		178,378		150,580
	Net income attributable to the Partnership’s common unitholders per common unit (1)
	Basic	$	0.05	$	0.63	$	0.13	$	0.52
	Diluted	$	0.05	$	0.55	$	0.12	$	0.45
	(1)     Earnings per Class B units equals zero as Class B unitholders are not entitled to receive distributions and therefore no income is allocable to Class B units under the two class method.

Segment_Information

Segment Information	6 Months Ended
	Jun. 30, 2014
Segment Information	'
Segment Information	'
	14. Segment Information
	The Partnership prepares segment information in accordance with GAAP. However, certain items below Income from operations in the accompanying Condensed Consolidated Statements of Operations, certain compensation expense, certain other non-cash items and any gains (losses) from derivative instruments are not allocated to individual segments. Management does not consider these items allocable to or controllable by any individual segment and therefore excludes these items when evaluating segment performance. Segment results are also adjusted to exclude the portion of operating income attributable to the non-controlling interests.  As disclosed in Note 3, Ohio Gathering was deconsolidated effective June 1, 2014 and its financial position as of June 30, 2014 and results of operations are reported under the equity method of accounting as of June 30, 2014 and for the month of June 2014, respectively. However, the Partnership’s Chief Executive Officer and “chief operating decision maker” continues to view the Utica Segment inclusive of Ohio Gathering, and review its financial information as if they are still consolidated.
	The tables below present the Partnership’s segment profit measure, Operating income before items not allocated to segments for the three months ended June 30, 2014 and 2013 for the reported segments (in thousands):
	Three months ended June 30, 2014:
		Marcellus			Utica			Northeast		Southwest		Elimination (1)			Total
	Segment revenue	$	183,734		$	30,826		$	43,777	$	271,140	$	(900	)	$	528,577
	Purchased product costs	39,710			7,353			15,169		153,628		—			215,860
	Net operating margin	144,024			23,473			28,608		117,512		(900		)	312,717
	Facility expenses	33,755			12,174			8,509		34,354		(900		)	87,892
	Portion of operating income attributable to non-controlling interests	—			4,687			—		6		—			4,693
	Operating income before items not allocated to segments	$	110,269		$	6,612		$	20,099	$	83,152	$	—		$	220,132
	Three months ended June 30, 2013:
		Marcellus			Utica			Northeast		Southwest		Total
	Segment revenue	$	120,057		$	3,594		$	45,365	$	227,842	$	396,858
	Purchased product costs	16,993			—			15,126		123,240		155,359
	Net operating margin	103,064			3,594			30,239		104,602		241,499
	Facility expenses	22,272			6,412			6,655		29,778		65,117
	Portion of operating (loss) income attributable to non-controlling interests	—			(1,143		)	—		53		(1,090		)
	Operating income (loss) before items not allocated to segments	$	80,792		$	(1,675	)	$	23,584	$	74,771	$	177,472
	(1)     Amounts represent revenues and expenses associated with the Northeast segment fractionation completed on behalf of the Marcellus segment, which occurs when NGL volumes in the Marcellus exceed its fractionation capacity.
	The following is a reconciliation of segment revenue to total revenue and operating income before items not allocated to segments to income before provision for income tax for the three months ended June 30, 2014 and 2013 (in thousands):
		Three months ended June 30,
		2014			2013
	Total segment revenue	$	528,577		$	396,858
	Derivative (loss) gain not allocated to segments	(6,753		)	19,699
	Revenue adjustment for unconsolidated affiliate (1)	(3,833		)	—
	Revenue deferral adjustment and other (2)	375			(1,437		)
	Total revenue	$	518,366		$	415,120
	Operating income before items not allocated to segments	$	220,132		$	177,472
	Portion of operating income (loss) attributable to non-controlling interests	4,184			(1,090		)
	Derivative (loss) gain not allocated to segments	(20,762		)	39,331
	Revenue adjustment for unconsolidated affiliate (1)	(3,833		)	—
	Revenue deferral adjustment and other (2)	375			(1,437		)
	Compensation expense included in facility expenses not allocated to segments	(903		)	(368		)
	Facility expense and purchase product cost adjustments for unconsolidated affiliate (3)	2,598			—
	Portion of operating loss attributable to non-controlling interests of an unconsolidated affiliate (4)	509			—
	Facility expense adjustments (5)	2,688			2,688
	Selling, general and administrative expenses	(27,701		)	(25,499		)
	Depreciation	(104,078		)	(71,562		)
	Amortization of intangible assets	(15,965		)	(17,092		)
	(Loss) gain on disposal of property, plant and equipment	(1,450		)	37,736
	Accretion of asset retirement obligations	(168		)	(157		)
	Income from operations	55,626			140,022
	Equity in (loss) earnings from unconsolidated affiliates	(721		)	430
	Interest income	10			62
	Interest expense	(43,391		)	(36,955		)
	Amortization of deferred financing costs and debt discount (a component of interest expense)	(1,449		)	(1,784		)
	Miscellaneous income, net	33			6
	Income before provision for income tax	$	10,108		$	101,781
	(1)     Revenue adjustment for unconsolidated affiliate relates to Ohio Gathering revenue for the month of June 2014 (See note above and Note 3).
	(2)     Revenue deferral amount relates primarily to certain contracts in which the cash consideration that the Partnership receives for providing service is greater during the initial years of the contract compared to the later years. In accordance with GAAP, the revenue is recognized evenly over the term of the contract as the Partnership will perform a similar level of service for the entire term. Therefore, the revenue recognized in the current reporting period is less than the cash received. However, the Partnership’s chief operating decision maker and management evaluate the segment performance based on the cash consideration received and therefore, the impact of the revenue deferrals is excluded for segment reporting purposes. For the three months ended June 30, 2014, approximately $0.2 million and $1.5 million of the revenue deferral adjustment is attributable to the Southwest segment and Northeast segment, respectively. In comparison, for the three months ended June 30, 2013, approximately $0.2 million and $1.4 million of the revenue deferral adjustment was attributable to the Southwest segment and Northeast segment, respectively. Beginning in 2015, the cash consideration received from these contracts will decline and the reported segment revenue will be less than the revenue recognized for GAAP purposes. Other consists of management fee revenues from unconsolidated affiliates of $2.1 million for the three months ended June 30, 2014 compared to $0.2 million for three months ended June 30, 2013.
	(3)     Facility expense and purchase product cost adjustments for unconsolidated affiliate consist of the facility expenses and purchase product costs related to Ohio Gathering for the month of June 2014 (See note above and Note 3).
	(4)     Portion of operating loss attributable to non-controlling interests of an unconsolidated affiliate amount relates to Summit’s portion of Ohio Gathering’s operating income, which is included in segment operating income calculation as if Ohio Gathering is consolidated (See note above and Note 3).
	(5)     Facility expenses adjustments consist of the reallocation of the interest expense related to the SMR, which is included in facility expenses for the purposes of evaluating the performance of the Southwest segment.
	The tables below present the Partnership’s segment profit measure, Operating income before items not allocated to segments, and capital expenditures for the six months ended June 30, 2014 and 2013 for the reported segments (in thousands):
	Six months ended June 30, 2014:
		Marcellus			Utica (1)			Northeast		Southwest		Elimination (2)			Total
	Segment revenue	$	358,893		$	54,592		$	105,030	$	530,470	$	(2,471	)	$	1,046,514
	Purchased product costs	74,000			11,488			35,624		306,312		—			427,424
	Net operating margin	284,893			43,104			69,406		224,158		(2,471		)	619,090
	Facility expenses	69,228			24,026			15,623		66,876		(2,471		)	173,282
	Portion of operating income attributable to non-controlling interests	—			7,823			—		5		—			7,828
	Operating income before items not allocated to segments	$	215,665		$	11,255		$	53,783	$	157,277	$	—		$	437,980
Capital expenditures	$	792,927		$	433,615		$	1,300	$	78,588	$	—		$	1,306,430
Capital expenditures for Ohio Gathering after deconsolidation (1)														(40,013		)
Capital expenditures not allocated to segments														8,906
Total capital expenditures														$	1,275,323
Six months ended June 30, 2013:
	Marcellus			Utica			Northeast		Southwest		Total
Segment revenue	$	228,554		$	4,217		$	102,701	$	436,208	$	771,680
Purchased product costs	35,786			—			34,788		237,342		307,916
Net operating margin	192,768			4,217			67,913		198,866		463,764
Facility expenses	44,908			10,374			13,179		58,468		126,929
Portion of operating (loss) income attributable to non-controlling interests	—			(2,482		)	—		117		(2,365		)
Operating income (loss) before items not allocated to segments	$	147,860		$	(3,675	)	$	54,734	$	140,281	$	339,200
Capital expenditures	$	729,040		$	640,819		$	2,509	$	57,816	$	1,430,184
Capital expenditures not allocated to segments											4,900
Total capital expenditures											$	1,435,084
(1)     As disclosed in Note 3, Ohio Gathering was deconsolidated effective June 1, 2014, and its financial position as of June 30, 2014 and results of operations are reported under the equity method of accounting as of June 30, 2014 and for the month of June 2014, respectively. However, the Partnership’s Chief Executive Officer and “chief operating decision maker” continues to view the Utica Segment inclusive of Ohio Gathering, and review its financial information as if they are still combined. The Utica segment includes $40.0 million related to Ohio Gathering capital expenditures after deconsolidation on June 1, 2014 (See Note 3).
(2)     Amounts represent revenues and expenses associated with the Northeast segment fractionation completed on behalf of the Marcellus segment, which occurs when NGL volumes in the Marcellus exceed its fractionation capacity.
The following is a reconciliation of segment revenue to total revenue and operating income before items not allocated to segments to income before provision for income tax for the six months ended June 30, 2014 and 2013 (in thousands):
	Six months ended June 30,
	2014			2013
Total segment revenue	$	1,046,514		$	771,680
Derivative (loss) gain not allocated to segments	(10,720		)	19,514
Revenue adjustment for unconsolidated affiliate (1)	(3,833		)	—
Revenue deferral adjustment and other (2)	(1,119		)	(2,801		)
Total revenue	$	1,030,842		$	788,393
Operating income before items not allocated to segments	$	437,980		$	339,200
Portion of operating income (loss) attributable to non-controlling interests	7,319			(2,365		)
Derivative (loss) gain not allocated to segments	(16,663		)	50,182
Revenue adjustment for unconsolidated affiliate (1)	(3,833		)	—
Revenue deferral adjustment and other (2)	(1,119		)	(2,801		)
Compensation expense included in facility expenses not allocated to segments	(1,906		)	(754		)
Facility expense and purchase product cost adjustments for unconsolidated affiliate (3)	2,598			—
Portion of operating loss attributable to non-controlling interests of an unconsolidated affiliate (4)	509			—
Facility expense adjustments (5)	5,376			5,376
Selling, general and administrative expenses	(62,991		)	(50,741		)
Depreciation	(206,007		)	(139,579		)
Amortization of intangible assets	(31,943		)	(31,922		)
(Loss) gain on disposal of property, plant and equipment	(1,357		)	37,598
Accretion of asset retirement obligations	(336		)	(509		)
Income from operations	127,627			203,685
Equity in (loss) earnings from unconsolidated affiliates	(471		)	665
Interest income	19			211
Interest expense	(84,375		)	(75,291		)
Amortization of deferred financing costs and debt discount (a component of interest expense)	(4,273		)	(3,614		)
Loss on redemption of debt	—			(38,455		)
Miscellaneous income, net	43			6
Income before provision for income tax	$	38,570		$	87,207
(1)     Revenue adjustment for unconsolidated affiliate relates to Ohio Gathering revenue for the month of June 2014 (See note above and Note 3).
(2)     Revenue deferral amount relates primarily to certain contracts in which the cash consideration that the Partnership receives for providing service is greater during the initial years of the contract compared to the later years. In accordance with GAAP, the revenue is recognized evenly over the term of the contract as the Partnership will perform a similar level of service for the entire term. Therefore, the revenue recognized in the current reporting period is less than the cash received. However, the Partnership’s chief operating decision maker and management evaluate the segment performance based on the cash consideration received and therefore, the impact of the revenue deferrals is excluded for segment reporting purposes. For the six months ended June 30, 2014, approximately $0.4 million and $3.4 million of the revenue deferral adjustment is attributable to the Southwest segment and Northeast segment, respectively. In comparison, for the six months ended June 30, 2013, approximately $0.4 million and $3.0 million of the revenue deferral adjustment was attributable to the Southwest segment and Northeast segment, respectively. Beginning in 2015, the cash consideration received from these contracts will decline and the reported segment revenue will be less than the revenue recognized for GAAP purposes. Other consists of management fee revenues from unconsolidated affiliates of $2.7 million for the six months ended June 30, 2014 compared to $0.6 million for six months ended June 30, 2013.
(3)     Facility expense and purchase product cost adjustments for unconsolidated affiliate consist of the facility expenses and purchase product costs related to Ohio Gathering for the month of June 2014 (See note above and Note 3).
(4)     Portion of operating loss attributable to non-controlling interests of an unconsolidated affiliate amount relates to Summit’s proportionate share of Ohio Gathering’s operating income, which is included in segment operating income calculation as if Ohio Gathering is consolidated (See note above and Note 3).
(5)     Facility expenses adjustments consist of the reallocation of the interest expense related to the SMR, which is included in facility expenses for the purposes of evaluating the performance of the Southwest segment.
The table below presents information about segment assets as of June 30, 2014 and December 31, 2013 (in thousands):
	June 30, 2014			December 31, 2013
Marcellus	$	5,108,339		$	4,529,028
Utica (1)	1,882,369			1,646,995
Northeast	525,743			572,855
Southwest	2,424,174			2,389,057
Total segment assets	9,940,625			9,137,935
Assets not allocated to segments:
Certain cash and cash equivalents	51,592			63,086
Fair value of derivatives	5,935			11,962
Investment in unconsolidated affiliates	71,324			75,627
Receivables from unconsolidated affiliate	13,977			—
Other (2)	99,937			107,813
Total assets	$	10,183,390		$	9,396,423
(1)     The June 30, 2014 amount excludes assets related to Ohio Gathering, which was deconsolidated on June 1, 2014 and reported as an equity investment as of June 30, 2014 (See note above and Note 3).  This amount includes Utica’s investment in Ohio Gathering.
(2)     Includes corporate fixed assets, deferred financing costs, income tax receivable, receivables and other corporate assets not allocated to segments.

Supplemental_Condensed_Consoli

Supplemental Condensed Consolidating Financial Information	6 Months Ended
	Jun. 30, 2014
Supplemental Condensed Consolidating Financial Information	'
Supplemental Condensed Consolidating Financial Information	'
	15. Supplemental Condensed Consolidating Financial Information
	MarkWest Energy Partners L.P. has no significant operations independent of its subsidiaries. As of June 30, 2014, the Partnership’s obligations under the outstanding Senior Notes (see Note 9) were fully, jointly and severally guaranteed, by all of the subsidiaries that are owned 100% by the Partnership, other than MarkWest Liberty Midstream and its subsidiaries. The guarantees are unconditional except for certain customary circumstances in which a subsidiary would be released from the guarantee under the indentures (see Note 16 to the Consolidated Financial Statements included in Item 8 of the Partnership’s Annual Report on Form 10-K for the year ended December 31, 2013 for discussion of these circumstances). Subsidiaries that are not 100% owned by the Partnership do not guarantee the Senior Notes. For the purpose of the following financial information, the Partnership’s investments in its subsidiaries and the guarantor subsidiaries’ investments in their subsidiaries are presented in accordance with the equity method of accounting. The co-issuer, MarkWest Energy Finance Corporation, has no independent assets or operations. Condensed consolidating financial information for MarkWest Energy Partners L.P. and its combined guarantor and combined non-guarantor subsidiaries as of June 30, 2014 and December 31, 2013 and for the three and six months ended June 30, 2014 and 2013 is as follows (in thousands):
	Condensed Consolidating Balance Sheets
		As of June 30, 2014
		Parent			Guarantor			Non-			Consolidating			Consolidated
					Subsidiaries			Guarantor			Adjustments
								Subsidiaries
	ASSETS
	Current assets:
	Cash and cash equivalents	$	15		$	51,580		$	247,817		$	—		$	299,412
	Restricted cash	—			—			10,000			—			10,000
	Receivables and other current assets	5,094			273,520			138,497			—			417,111
	Intercompany receivables	2,012,956			76,174			67,906			(2,157,036		)	—
	Fair value of derivative instruments	—			4,828			1,107			—			5,935
	Receivables from unconsolidated affiliates	—			1,546			12,431			—			13,977
	Total current assets	2,018,065			407,648			477,758			(2,157,036		)	746,435
	Total property, plant and equipment, net	8,340			2,139,094			5,650,985			(61,531		)	7,736,888
	Other long-term assets:
	Restricted cash	—			—			10,000			—			10,000
	Investment in unconsolidated affiliates	—			81,843			558,603			(10,519		)	629,927
	Investment in consolidated affiliates	5,813,027			5,523,135			—			(11,336,162		)	—
	Intangibles, net of accumulated amortization	—			571,361			270,866			—			842,227
	Intercompany notes receivable	137,000			—			—			(137,000		)	—
	Other long-term assets	49,898			92,065			75,950			—			217,913
	Total assets	$	8,026,330		$	8,815,146		$	7,044,162		$	(13,702,248	)	$	10,183,390
	LIABILITIES AND EQUITY
	Current liabilities:
	Intercompany payables	$	3,109		$	2,074,930		$	78,997		$	(2,157,036	)	$	—
	Fair value of derivative instruments	—			20,288			1,642			—			21,930
	Other current liabilities	58,602			284,191			380,010			(2,262		)	720,541
	Total current liabilities	61,711			2,379,409			460,649			(2,159,298		)	742,471
	Deferred income taxes	3,815			301,710			—			—			305,525
	Long-term intercompany financing payable	—			137,000			96,296			(233,296		)	—
	Fair value of derivative instruments	—			35,668			—			—			35,668
	Long-term debt, net of discounts	3,464,637			—			—			—			3,464,637
	Other long-term liabilities	6,657			148,332			7,839			—			162,828
	Redeemable non-controlling interest	—			—			—			70,711			70,711
	Equity:
	Common Units	3,887,485			5,813,027			6,479,378			(12,265,897		)	3,913,993
	Class B Units	602,025			—			—			—			602,025
	Non-controlling interest in consolidated subsidiaries	—			—			—			885,532			885,532
	Total equity	4,489,510			5,813,027			6,479,378			(11,380,365		)	5,401,550
	Total liabilities and equity	$	8,026,330		$	8,815,146		$	7,044,162		$	(13,702,248	)	$	10,183,390
		As of December 31, 2013
		Parent			Guarantor			Non-			Consolidating			Consolidated
					Subsidiaries			Guarantor			Adjustments
								Subsidiaries
	ASSETS
	Current assets:
	Cash and cash equivalents	$	224		$	79,363		$	5,718		$	—		$	85,305
	Restricted cash	—			—			10,000			—			10,000
	Receivables and other current assets	6,248			266,610			134,880			—			407,738
	Intercompany receivables	1,194,955			78,010			125,115			(1,398,080		)	—
	Fair value of derivative instruments	—			10,444			1,013			—			11,457
	Total current assets	1,201,427			434,427			276,726			(1,398,080		)	514,500
	Total property, plant and equipment, net	5,379			2,149,845			5,622,602			(84,657		)	7,693,169
	Other long-term assets:
	Restricted cash	—			—			10,000			—			10,000
	Investment in unconsolidated affiliates	—			75,627			—			—			75,627
	Investment in consolidated affiliates	5,741,374			4,541,617			—			(10,282,991		)	—
	Intangibles, net of accumulated amortization	—			595,995			278,797			—			874,792
	Fair value of derivative instruments	—			505			—			—			505
	Intercompany notes receivable	151,200			—			—			(151,200		)	—
Other long-term assets	52,338			92,276			83,216			—			227,830
Total assets	$	7,151,718		$	7,890,292		$	6,271,341		$	(11,916,928	)	$	9,396,423
LIABILITIES AND EQUITY
Current liabilities:
Intercompany payables	$	—		$	1,315,707		$	82,373		$	(1,398,080	)	$	—
Fair value of derivative instruments	—			26,382			2,456			—			28,838
Other current liabilities	58,110			199,146			583,810			(2,131		)	838,935
Total current liabilities	58,110			1,541,235			668,639			(1,400,211		)	867,773
Deferred income taxes	3,407			284,159			—			—			287,566
Long-term intercompany financing payable	—			151,200			97,461			(248,661		)	—
Fair value of derivative instruments	—			27,763			—			—			27,763
Long-term debt, net of discounts	3,023,071			—			—			—			3,023,071
Other long-term liabilities	3,745			144,561			8,194			—			156,500
Redeemable non-controlling interest	—			—			—			235,617			235,617
Equity:
Common Units	3,461,360			5,741,374			5,497,047			(11,223,486		)	3,476,295
Class B Units	602,025			—			—			—			602,025
Non-controlling interest in consolidated subsidiaries	—			—			—			719,813			719,813
Total equity	4,063,385			5,741,374			5,497,047			(10,503,673		)	4,798,133
Total liabilities and equity	$	7,151,718		$	7,890,292		$	6,271,341		$	(11,916,928	)	$	9,396,423
Condensed Consolidating Statements of Operations
	Three months ended June 30, 2014
	Parent			Guarantor			Non-			Consolidating			Consolidated
				Subsidiaries			Guarantor			Adjustments
							Subsidiaries
Total revenue	$	—		$	318,408		$	209,800		$	(9,842	)	$	518,366
Operating expenses:
Purchased product costs	—			180,638			47,150			—			227,788
Facility expenses	—			42,567			44,311			(1,288		)	85,590
Selling, general and administrative expenses	10,760			7,795			12,416			(3,270		)	27,701
Depreciation and amortization	288			49,719			71,409			(1,373		)	120,043
Other operating expenses (income)	—			352			6,536			(5,270		)	1,618
Total operating expenses	11,048			281,071			181,822			(11,201		)	462,740
(Loss) income from operations	(11,048		)	37,337			27,978			1,359			55,626
Earnings from consolidated affiliates	54,074			18,928			—			(73,002		)	—
Other expense, net	(44,526		)	(5,382		)	(4,978		)	9,368			(45,518		)
Income before provision for income tax	(1,500		)	50,883			23,000			(62,275		)	10,108
Provision for income tax (benefit) expense	251			(3,191		)	—			—			(2,940		)
Net income	(1,751		)	54,074			23,000			(62,275		)	13,048
Net income attributable to non-controlling interest	—			—			—			(4,071		)	(4,071		)
Net income attributable to the Partnership’s unitholders	$	(1,751	)	$	54,074		$	23,000		$	(66,346	)	$	8,977
	Three months ended June 30, 2013
	Parent			Guarantor			Non-			Consolidating			Consolidated
				Subsidiaries			Guarantor			Adjustments
							Subsidiaries
Total revenue	$	—		$	298,097		$	126,515		$	(9,492	)	$	415,120
Operating expenses:
Purchased product costs	—			117,813			17,114			—			134,927
Facility expenses	—			34,497			29,485			(385		)	63,597
Selling, general and administrative expenses	12,074			6,646			8,451			(1,672		)	25,499
Depreciation and amortization	242			45,457			44,292			(1,337		)	88,654
Other operating expenses (income)	—			573			(40,233		)	2,081			(37,579		)
Total operating expenses	12,316			204,986			59,109			(1,313		)	275,098
(Loss) income from operations	(12,316		)	93,111			67,406			(8,179		)	140,022
Earnings from consolidated affiliates	132,913			62,611			—			(195,524		)	—
Other expense, net	(40,102		)	(6,820		)	(2,997		)	11,678			(38,241		)
Income before provision for income tax	80,495			148,902			64,409			(192,025		)	101,781
Provision for income tax (benefit) expense	294			15,989			—			—			16,283
Net income	80,201			132,913			64,409			(192,025		)	85,498
Net income attributable to non-controlling interest	—			—			—			(1,799		)	(1,799		)
Net income attributable to the Partnership’s unitholders	$	80,201		$	132,913		$	64,409		$	(193,824	)	$	83,699
	Six months ended June 30, 2014
	Parent			Guarantor			Non-			Consolidating			Consolidated
				Subsidiaries			Guarantor			Adjustments
							Subsidiaries
Total revenue	$	—		$	643,909		$	408,918		$	(21,985	)	$	1,030,842
Operating expenses:
Purchased product costs	—			345,821			85,733			—			431,554
Facility expenses	—			79,600			92,682			(3,255		)	169,027
Selling, general and administrative expenses	24,415			18,311			25,765			(5,500		)	62,991
Depreciation and amortization	568			98,839			141,222			(2,679		)	237,950
Other operating expenses (income)	—			193			6,770			(5,270		)	1,693
Total operating expenses	24,983			542,764			352,172			(16,704		)	903,215
(Loss) income from operations	(24,983		)	101,145			56,746			(5,281		)	127,627
Earnings from consolidated affiliates	121,784			41,317			—			(163,101		)	—
Other expense, net	(87,688		)	(11,480		)	(7,934		)	18,045			(89,057		)
Income before provision for income tax	9,113			130,982			48,812			(150,337		)	38,570
Provision for income tax (benefit) expense	408			9,198			—			—			9,606
Net income	8,705			121,784			48,812			(150,337		)	28,964
Net income attributable to non-controlling interest	—			—			—			(7,495		)	(7,495		)
Net (loss) income attributable to the Partnership’s unitholders	$	8,705		$	121,784		$	48,812		$	(157,832	)	$	21,469
	Six months ended June 30, 2013
	Parent			Guarantor			Non-			Consolidating			Consolidated
				Subsidiaries			Guarantor			Adjustments
							Subsidiaries
Total revenue	$	—		$	569,065		$	235,857		$	(16,529	)	$	788,393
Operating expenses:
Purchased product costs	—			240,763			36,017			—			276,780
Facility expenses	—			66,775			56,387			(387		)	122,775
Selling, general and administrative expenses	24,108			13,619			15,528			(2,514		)	50,741
Depreciation and amortization	519			89,510			84,295			(2,823		)	171,501
Other operating expenses (income)	—			1,338			(40,507		)	2,080			(37,089		)
Total operating expenses	24,627			412,005			151,720			(3,644		)	584,708
(Loss) income from operations	(24,627		)	157,060			84,137			(12,885		)	203,685
Earnings from consolidated affiliates	202,874			81,729			—			(284,603		)	—
Loss on redemption of debt	(38,455		)	—			—			—			(38,455		)
Other expense, net	(83,102		)	(13,236		)	(6,282		)	24,597			(78,023		)
Income before provision for income tax	56,690			225,553			77,855			(272,891		)	87,207
Provision for income tax (benefit) expense	161			22,679			—			—			22,840
Net income	56,529			202,874			77,855			(272,891		)	64,367
Net income attributable to non-controlling interest	—			—			—			3,874			3,874
Net (loss) income attributable to the Partnership’s unitholders	$	56,529		$	202,874		$	77,855		$	(269,017	)	$	68,241
Condensed Consolidating Statements of Cash Flows
	Six months ended June 30, 2014
	Parent			Guarantor			Non-			Consolidating			Consolidated
				Subsidiaries			Guarantor			Adjustments
							Subsidiaries
Net cash (used in) provided by operating activities	$	(97,223	)	$	263,284		$	187,138		$	3,624		$	356,823
Cash flows from investing activities:
Capital expenditures	(5,116		)	(108,203		)	(1,157,346		)	(4,658		)	(1,275,323		)
Equity investments in consolidated affiliates	(30,038		)	(1,090,000		)	—			1,120,038			—
Investment in unconsolidated affiliates	—			(8,540		)	(67,514		)	—			(76,054		)
Distributions from consolidated affiliates	63,158			151,110			—			(214,268		)	—
Investment in intercompany notes, net	14,200			—			—			(14,200		)	—
Proceeds from disposal of property, plant and equipment	—			4,164			17,398			—			21,562
Proceeds from sale of equity interest in unconsolidated affiliate	—			—			324,657			—			324,657
Net cash flows provided by (used in) investing activities	42,204			(1,051,469		)	(882,805		)	886,912			(1,005,158		)
Cash flows from financing activities:
Proceeds from public equity offerings, net	711,837			—			—			—			711,837
Proceeds from Credit Facility	1,923,500			—			—			—			1,923,500
Payments Credit Facility	(1,482,300		)	—			—			—			(1,482,300		)
Payments related to intercompany financing, net	—			(14,200		)	(1,034		)	15,234			—
Payments for debt issue costs and deferred financing costs	(2,045		)	—			—			—			(2,045		)
Contributions from parent and affiliates	—			30,038			1,090,000			(1,120,038		)	—
Share-based payment activity	(8,943		)	—			—			—			(8,943		)
Payment of distributions	(278,316		)	(63,158		)	(151,200		)	214,268			(278,406		)
Payments of SMR liability	—			(1,201		)	—			—			(1,201		)
Intercompany advances, net	(808,923		)	808,923			—						—
										—
Net cash flows (used in) provided by financing activities	54,810			760,402			937,766			(890,536		)	862,442
Net (decrease) increase in cash	(209		)	(27,783		)	242,099			—			214,107
Cash and cash equivalents at beginning of year	224			79,363			5,718			—			85,305
Cash and cash equivalents at end of period	$	15		$	51,580		$	247,817		$	—		$	299,412
	Six months ended June 30, 2013
	Parent			Guarantor			Non-			Consolidating			Consolidated
				Subsidiaries			Guarantor			Adjustments
							Subsidiaries
Net cash (used in) provided by operating activities	$	(79,362	)	$	129,228		$	116,760		$	10,970		$	177,596
Cash flows from investing activities:
Restricted cash	—			—			25,500			—			25,500
Capital expenditures	(480		)	(53,319		)	(1,369,397		)	(11,888		)	(1,435,084		)
Equity investments in consolidated affiliates	(28,823		)	(783,600		)	—			812,423			—
Investment in unconsolidated affiliates	—			(8,336		)	—			—			(8,336		)
Distributions from consolidated affiliates	47,860			389,300			—			(437,160		)	—
Acquisition of business, net of cash acquired	—			(225,210		)	—			—			(225,210		)
Proceeds from disposal of property, plant and equipment	—			43			208,066			—			208,109
Net cash flows provided by (used in) investing activities	18,557			(681,122		)	(1,135,831		)	363,375			(1,435,021		)
Cash flows from financing activities:
Proceeds from public equity offerings, net	348,352			—			—			—			348,352
Proceeds from long-term debt	1,000,000			—			—			—			1,000,000
Payments of long-term debt	(501,112		)	—			—			—			(501,112		)
Payments of premiums on redemption of long-term debt	(31,516		)	—			—			—			(31,516		)
Payments for debt issue costs and deferred financing costs	(14,046		)	—			—			—			(14,046		)
Payments related to intercompany financing, net	—			—			(918		)	918			—
Contributions from parent and affiliates	—			28,823			783,600			(812,423		)	—
Contribution from non-controlling interest	—			—			685,219			—			685,219
Share-based payment activity	(5,206		)	650			—			—			(4,556		)
Payment of distributions	(214,903		)	(47,860		)	(389,412		)	437,160			(215,015		)
Payments of SMR liability	—			(1,103		)	—			—			(1,103		)
Intercompany advances, net	(595,591		)	595,591			—			—			—
Net cash flows (used in) provided by financing activities	(14,022		)	576,101			1,078,489			(374,345		)	1,266,223
Net (decrease) increase in cash	(74,827		)	24,207			59,418			—			8,798
Cash and cash equivalents at beginning of year	210,015			102,979			32,762			—			345,756
Cash and cash equivalents at end of period	$	135,188		$	127,186		$	92,180		$	—		$	354,554

Supplemental_Cash_Flow_Informa

Supplemental Cash Flow Information	6 Months Ended
	Jun. 30, 2014
Supplemental Cash Flow Information	'
Supplemental Cash Flow Information	'
	16. Supplemental Cash Flow Information
	The following table provides information regarding supplemental cash flow information (in thousands):
		Six months ended June 30,
		2014		2013
	Supplemental disclosures of cash flow information:
	Cash paid for interest, net of amounts capitalized	$	81,031	$	60,835
	Cash received for income taxes, net	321		16,591
	Supplemental schedule of non-cash investing and financing activities:
	Accrued property, plant and equipment	$	312,519	$	524,445
	Interest capitalized on construction in progress	12,679		19,090
	Issuance of common units for vesting of share-based payment awards	7,754		4,495

Business_Combinations_Tables

Business Combinations (Tables)	6 Months Ended
	Jun. 30, 2014
Business Combination	'
Summary of preliminary purchase price allocation	'
	The following table summarizes the purchase price allocation for the Buffalo Creek Acquisition (in thousands):
	Assets:
	Property, plant and equipment	144,115
	Goodwill	2,682
	Intangible asset	84,500
	Liabilities:
	Accounts payable	(6,087		)
	Total	$	225,210

Derivative_Financial_Instrumen1

Derivative Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2014
Derivative Financial Instruments	'
Schedule of notional amounts of derivative contracts	'
	As of June 30, 2014, the Partnership had the following outstanding commodity contracts that were entered into to manage cash flow risk associated with future sales of NGLs or future purchases of natural gas:
	Derivative contracts not designated as hedging instruments	Financial		Notional Quantity
		Position		(net)
	Crude Oil (bbl)	Short		935,540
	Natural Gas (MMBtu)	Long		1,581,160
	NGLs (gal)	Short		83,399,447
Schedule reconciling liability recorded for an embedded derivative	'
	See the following table for a reconciliation of the liability recorded for the embedded derivative as of June 30, 2014 (in thousands):
	Fair value of commodity contract	$	97,838
	Inception value for period from April 1, 2015 to December 31, 2022	(53,507		)
	Derivative liability as of June 30, 2014	$	44,331
Schedule of derivative contracts not designated as hedging instruments and their balance sheet location	'
	The impact of the Partnership’s derivative instruments on its Condensed Consolidated Balance Sheets is summarized below (in thousands):
		Assets						Liabilities
	Derivative instruments not designated as hedging	Fair Value at			Fair Value at			Fair Value at			Fair Value at
	instruments and their balance sheet location	June 30,			December 31,			June 30,			December 31,
		2014			2013			2014			2013
	Commodity contracts(1)
	Fair value of derivative instruments — current	$	5,935		$	11,457		$	(21,930	)	$	(28,838	)
	Fair value of derivative instruments — long-term	—			505			(35,668		)	(27,763		)
	Total	$	5,935		$	11,962		$	(57,598	)	$	(56,601	)
	(1)     Includes Embedded Derivatives in Commodity Contracts as discussed above.
	The impact of the Partnership’s derivative instruments on its Condensed Consolidated Statements of Operations is summarized below (in thousands):
	Derivative contracts not designated as	Three months ended June 30,						Six months ended June 30,
	hedging instruments and the location of
	gain or (loss) recognized in income	2014			2013			2014			2013
	Revenue: Derivative (loss) gain
	Realized (loss) gain	$	(1,774	)	$	3,089		$	(9,381	)	$	6,987
	Unrealized (loss) gain	(4,979		)	16,610			(1,339		)	12,527
	Total revenue: derivative (loss) gain	(6,753		)	19,699			(10,720		)	19,514
	Derivative (loss) gain related to purchased product costs
	Realized loss	(144		)	(1,045		)	(258		)	(3,125		)
	Unrealized (loss) gain	(11,820		)	21,477			(3,908		)	34,261
	Total derivative (loss) gain related to purchase product costs	(11,964		)	20,432			(4,166		)	31,136
	Derivative loss related to facility expenses
	Unrealized loss	(2,045		)	(800		)	(1,777		)	(468		)
	Total (loss) gain	$	(20,762	)	$	39,331		$	(16,663	)	$	50,182
Schedule of impact on the balance sheet if Partnership had elected to net derivative positions subject to master netting arrangements	'
	The table below summarizes the impact if the Partnership had elected to net its derivative positions that are subject to master netting arrangements (in thousands):
		Assets									Liabilities
	As of June 30, 2014	Gross			Gross			Net Amount			Gross			Gross		Net
		Amounts of			Amounts						Amounts of			Amounts		Amount
		Assets in the			Not Offset in						Liabilities in			Not Offset in
		Consolidated			the						the			the
		Balance			Consolidated						Consolidated			Consolidated
		Sheet			Balance						Balance			Balance
					Sheet						Sheet			Sheet
	Current
	Commodity contracts	$	4,435		$	(3,947	)	$	488		$	(12,045	)	$	3,947	$	(8,098	)
	Embedded derivatives in commodity contracts	1,500			—			1,500			(9,885		)	—		(9,885		)
	Total current derivative instruments	5,935			(3,947		)	1,988			(21,930		)	3,947		(17,983		)
	Non-current
	Commodity contracts	—			—			—			(1,222		)	—		(1,222		)
	Embedded derivatives in commodity contracts	—			—			—			(34,446		)	—		(34,446		)
	Total non-current derivative instruments	—			—			—			(35,668		)	—		(35,668		)
	Total derivative instruments	$	5,935		$	(3,947	)	$	1,988		$	(57,598	)	$	3,947	$	(53,651	)
		Assets									Liabilities
	As of December 31, 2013	Gross			Gross			Net Amount			Gross			Gross		Net
		Amounts of			Amounts						Amounts of			Amounts		Amount
		Assets in the			Not Offset in						Liabilities in			Not Offset in
		Consolidated			the						the			the
		Balance			Consolidated						Consolidated			Consolidated
		Sheet			Balance						Balance			Balance
					Sheet						Sheet			Sheet
	Current
	Commodity contracts	$	8,181		$	(7,017	)	$	1,164		$	(18,293	)	$	7,017	$	(11,276	)
	Embedded derivatives in commodity contracts	3,276			—			3,276			(10,545		)	—		(10,545		)
	Total current derivative instruments	11,457			(7,017		)	4,440			(28,838		)	7,017		(21,821		)
	Non-current
	Commodity contracts	505			—			505			—			—		—
	Embedded derivatives in commodity contracts	—			—			—			(27,763		)	—		(27,763		)
	Total non-current derivative instruments	505			—			505			(27,763		)	—		(27,763		)
	Total derivative instruments	$	11,962		$	(7,017	)	$	4,945		$	(56,601	)	$	7,017	$	(49,584	)

Fair_Value_Tables

Fair Value (Tables)	6 Months Ended
	Jun. 30, 2014
Fair Value	'
Schedule of derivative instruments carried at fair value	'
	The following table presents the derivative instruments carried at fair value as of June 30, 2014 and December 31, 2013 (in thousands):
	As of June 30, 2014	Assets			Liabilities
	Significant other observable inputs (Level 2)
	Commodity contracts	$	89		$	(6,829	)
	Significant unobservable inputs (Level 3)
	Commodity contracts	4,346			(6,438		)
	Embedded derivatives in commodity contracts	1,500			(44,331		)
	Total carrying value in Condensed Consolidated Balance Sheet	$	5,935		$	(57,598	)
	As of December 31, 2013	Assets			Liabilities
	Significant other observable inputs (Level 2)
	Commodity contracts	$	544		$	(4,691	)
	Significant unobservable inputs (Level 3)
	Commodity contracts	8,142			(13,602		)
	Embedded derivatives in commodity contracts	3,276			(38,308		)
	Total carrying value in Condensed Consolidated Balance Sheet	$	11,962		$	(56,601	)
Schedule of information about significant unobservable inputs used in the valuation of Level 3 instruments	'
	The following table provides additional information about the significant unobservable inputs used in the valuation of Level 3 instruments as of June 30, 2014. The market approach is used for valuation of all instruments.
	Level 3 Instrument	Balance		Unobservable Inputs		Value Range		Time Period
		Sheet
		Classification
	Commodity contracts	Assets		Forward propane prices (per gallon) (1)		$  1.06 - $1.09		Jul. 2014 - Dec. 2014
				Forward isobutane prices (per gallon) (1)		$  1.34 - $1.36		Jul. 2014 - Dec. 2014
				Forward normal butane prices (per gallon) (1)		$  1.26 - $1.31		Jul. 2014 - Dec. 2014
				Forward natural gasoline prices (per gallon) (1)		$  2.15 - $2.21		Jul. 2014 - Dec. 2014
				Crude option volatilities (%)		13.89% - 14.93%		Sep. 2014 - Dec. 2014
		Liabilities		Forward propane prices (per gallon) (1)		$  1.06 - $1.09		Jul. 2014 - Dec. 2014
				Forward isobutane prices (per gallon) (1)		$  1.34 - $1.36		Jul. 2014 - Dec. 2014
				Forward normal butane prices (per gallon) (1)		$  1.26 - $1.31		Jul. 2014 - Dec. 2014
				Forward natural gasoline prices (per gallon) (1)		$  2.15 - $2.21		Jul. 2014 - Dec. 2014
				Crude option volatilities (%)		8.24% - 17.99%		Jul. 2014 - Dec. 2014
	Embedded derivatives in commodity contracts	Asset		ERCOT Pricing (per MegaWatt Hour) (2)		$  36.16 - $52.42		Jul. 2014 - Dec. 2014
		Liabilities		Forward propane prices (per gallon) (1)		$  1.02 - $1.10		Jul. 2014 - Dec. 2022
				Forward isobutane prices (per gallon) (1)		$  1.27 - $1.38		Jul. 2014 - Dec. 2022
	Level 3 Instrument	Balance		Unobservable Inputs		Value Range		Time Period
		Sheet
		Classification
				Forward normal butane prices (per gallon) (1)		$  1.19 - $1.32		Jul. 2014 - Dec. 2022
				Forward natural gasoline prices (per gallon) (1)		$  1.80 - $2.21		Jul. 2014 - Dec. 2022
				Forward natural gas prices (per MMBtu) (3)		$  3.46 - $5.14		Jul. 2014 - Dec. 2022
				Probability of renewal (4)		0%
	(1)     NGL prices decrease over the respective period.
	(2)     The forward ERCOT prices utilized in the valuations are generally increasing over time with a seasonal spike in pricing in the summer months.
	(3)     Natural gas prices used in the valuations are generally at the lower end of the range in the early years and increase over time.
	(4)     The producer counterparty to the embedded derivative has the option to renew the gas purchase agreement and the related keep-whole processing agreement for two successive five year terms after 2022. The embedded gas purchase agreement cannot be renewed without the renewal of the related keep-whole processing agreement. Due to the significant number of years until the renewal options are exercisable and the high level of uncertainty regarding the counterparty’s future business strategy, the future commodity price environment and the future competitive environment for midstream services in the Appalachia area, management determined that a 0% probability of renewal is an appropriate assumption.
Schedule of changes in Level 3 fair value measurements	'
	The table below includes a roll forward of the balance sheet amounts for the three and six months ended June 30, 2014 and 2013 for net assets and liabilities classified by the Partnership within Level 3 of the valuation hierarchy (in thousands):
		Three months ended June 30, 2014
		Commodity Derivative			Embedded Derivatives
		Contracts (net)			in Commodity
					Contracts (net)
	Fair value at beginning of period	$	(751	)	$	(28,486	)
	Total loss (realized and unrealized) included in earnings (1)	(1,961		)	(16,479		)
	Settlements	620			2,134
	Fair value at end of period	$	(2,092	)	$	(42,831	)
	The amount of total losses for the period included in earnings attributable to the change in unrealized gains or losses relating to contracts still held at end of period (1)	$	(1,758	)	$	(15,959	)
		Three months ended June 30, 2013
		Commodity Derivative			Embedded Derivatives
		Contracts (net)			in Commodity
					Contracts (net)
	Fair value at beginning of period	$	12,477		$	(24,881	)
	Total gain (realized and unrealized) included in earnings (1)	16,896			20,459
	Settlements	(2,995		)	2,019
	Fair value at end of period	$	26,378		$	(2,403	)
	The amount of total losses for the period included in earnings attributable to the change in unrealized gains or losses relating to contracts still held at end of period (1)	$	14,755		$	20,766
		Six months ended June 30, 2014
		Commodity Derivative			Embedded Derivatives
		Contracts (net)			in Commodity
					Contracts (net)
	Fair value at beginning of period	$	(5,460	)	$	(35,032	)
	Total loss (realized and unrealized) included in earnings (1)	(4,238		)	(12,068		)
	Settlements	7,606			4,269
	Fair value at end of period	$	(2,092	)	$	(42,831	)
	The amount of total losses for the period included in earnings attributable to the change in unrealized gains or losses relating to contracts still held at end of period (1)	$	(1,319	)	$	(12,204	)
		Six months ended June 30, 2013
		Commodity Derivative			Embedded Derivatives
		Contracts (net)			in Commodity
					Contracts (net)
	Fair value at beginning of period	$	12,449		$	(33,957	)
	Total gain (realized and unrealized) included in earnings (1)	20,220			26,991
	Settlements	(6,291		)	4,563
	Fair value at end of period	$	26,378		$	(2,403	)
	The amount of total losses for the period included in earnings attributable to the change in unrealized gains or losses relating to contracts still held at end of period (1)	$	17,854		$	27,229
	(1)                 Gains and losses on Commodity Derivative Contracts classified as Level 3 are recorded in Revenue: Derivative (loss) gain. Gains and losses on Embedded Derivatives in Commodity Contracts are recorded in Purchased product costs, Derivative loss (gain) related to purchased product costs, Facility expenses and Derivative loss related to facility expenses.

Inventories_Tables

Inventories (Tables)	6 Months Ended
	Jun. 30, 2014
Inventories	'
Schedule of components of inventories	'
	Inventories consist of the following (in thousands):
		June 30, 2014		December 31, 2013
	NGLs	$	38,444	$	21,131
	Line fill	10,466		7,960
	Spare parts, materials and supplies	13,825		12,272
	Total inventories	$	62,735	$	41,363

LongTerm_Debt_Tables

Long-Term Debt (Tables)	6 Months Ended
	Jun. 30, 2014
Long-Term Debt	'
Schedule of long-term debt	'
	Debt is summarized below (in thousands):
		June 30, 2014		December 31, 2013
	Credit Facility
	Credit Facility, variable interest, due March 2019 (1)	$	441,200	$	—
	Senior Notes (2)
	2020 Senior Notes, 6.75% interest, issued November 2010 and due November 2020	500,000		500,000
	2021 Senior Notes, 6.5% interest, net of discount of $444 and $474, respectively, issued February and March 2011 and due August 2021	324,556		324,526
	2022 Senior Notes, 6.25% interest, issued October 2011 and due June 2022	455,000		455,000
	2023A Senior Notes, 5.5% interest, net of discount of $6,119 and $6,455, respectively, issued August 2012 and due February 2023	743,881		743,545
	2023B Senior Notes, 4.5% interest, issued January 2013 and due July 2023	1,000,000		1,000,000
	Total long-term debt	$	3,464,637	$	3,023,071
	(1)     Applicable interest rate was 4.5% for $166.2 million and 2.4% for $275.0 million at June 30, 2014.  The carrying amount of the Credit Facility approximates fair value due to the short-term and variable nature of the borrowings.  The fair value of the Partnership’s Credit Facility is considered a Level 2 measurement.
	(2)     The estimated aggregate fair value of the senior notes (collectively, the “Senior Notes”) was approximately $3,217 million and $3,079 million as of June 30, 2014 and December 31, 2013, respectively, based on quoted prices in an inactive market. The fair value of the Partnership’s Senior Notes is considered a Level 3 measurement.

Equity_Tables

Equity (Tables)	6 Months Ended
	Jun. 30, 2014
Equity	'
Schedule of distributions of available cash and range of unit prices	'
	Distributions of Available Cash and Range of Unit Prices
		Common Unit Price				Distribution
						Per
						Common
	Quarter Ended	High		Low		Unit		Declaration Date	Record Date	Payment Date
	June 30, 2014	$	71.88	$	58.62	$	0.88	July 24, 2014	August 5, 2014	August 14, 2014
	March 31, 2014	$	73.42	$	61.6	$	0.87	April 22, 2014	May 7, 2014	May 15, 2014
	December 31, 2013	$	75.79	$	62.56	$	0.86	January 22, 2014	February 6, 2014	February 14, 2014

Income_Taxes_Tables

Income Taxes (Tables)	6 Months Ended
	Jun. 30, 2014
Income Taxes	'
Schedule of income tax rate reconciliation	'
	A reconciliation of the provision for income tax and the amount computed by applying the federal statutory rate to income before provision for income tax for the six months ended June 30, 2014 and 2013 is as follows (in thousands):
		Six months ended June 30, 2014
		Corporation			Partnership			Eliminations			Consolidated
	Income before provision for income tax	$	6,641		$	32,297		$	(368	)	$	38,570
	Federal statutory rate	35		%	0		%	0		%
	Federal income tax at statutory rate	2,324			—			—			2,324
	Permanent items	33			—			—			33
	State income taxes net of federal benefit	168			409			—			577
	Federal and state tax rate change	4,250			—			—			4,250
	Provision on income from Class A units (1)	2,422			—			—			2,422
	Provision for income tax	$	9,197		$	409		$	—		$	9,606
		Six months ended June 30, 2013
		Corporation			Partnership			Eliminations			Consolidated
	Income before provision for income tax	$	52,839		$	40,023		$	(5,655	)	$	87,207
	Federal statutory rate	35		%	0		%	0		%
	Federal income tax at statutory rate	18,494			—			—			18,494
	Permanent items	29			—			—			29
	State income taxes net of federal benefit	1,321			161			—			1,482
	Provision on income from Class A units (1)	2,835			—			—			2,835
	Provision for income tax	$	22,679		$	161		$	—		$	22,840
	(1)     The Corporation and the General Partner of the Partnership own Class A units of the Partnership that were received in the merger of the Corporation and the Partnership completed in February 2008. The Class A units share, on a pro-rata basis, in the income or loss of the Partnership, except for items attributable to the Partnership’s ownership of or sale of shares of the Corporation’s common stock. The provision for income tax on income from Class A units includes intra period allocations to continued operations and excludes allocations to equity.

Earnings_Loss_Per_Common_Unit_

Earnings (Loss) Per Common Unit (Tables)	6 Months Ended
	Jun. 30, 2014
Earnings Per Common Unit	'
Schedule of computation of basic and diluted net income per common unit	'
	The following table shows the computation of basic and diluted net income per common unit for the three and six months ended June 30, 2014 and 2013, and the weighted-average units used to compute basic and diluted net income per common unit (in thousands, except per unit data):
		Three months ended June 30,				Six months ended June 30,
		2014		2013		2014		2013
	Net income attributable to the Partnership’s unitholders	$	8,977	$	83,699	$	21,469	$	68,241
	Less: Income allocable to phantom units	551		554		1,096		1,100
	Income available for common unitholders - basic	8,426		83,145		20,373		67,141
	Add: Income allocable to phantom units and DER expense	574		569		1,141		1,135
	Income available for common unitholders - diluted	$	9,000	$	83,714	$	21,514	$	68,276
	Weighted average common units outstanding - basic	164,613		131,227		161,727		129,928
	Potential common shares (Class B and phantom units)	16,624		20,639		16,651		20,652
	Weighted average common units outstanding - diluted	181,237		151,866		178,378		150,580
	Net income attributable to the Partnership’s common unitholders per common unit (1)
	Basic	$	0.05	$	0.63	$	0.13	$	0.52
	Diluted	$	0.05	$	0.55	$	0.12	$	0.45
	(1)     Earnings per Class B units equals zero as Class B unitholders are not entitled to receive distributions and therefore no income is allocable to Class B units under the two class method.

Segment_Information_Tables

Segment Information (Tables)	6 Months Ended
	Jun. 30, 2014
Segment Information	'
Schedule of operating income and capital expenditures of reportable segments	'
	The tables below present the Partnership’s segment profit measure, Operating income before items not allocated to segments for the three months ended June 30, 2014 and 2013 for the reported segments (in thousands):
	Three months ended June 30, 2014:
		Marcellus			Utica			Northeast		Southwest		Elimination (1)			Total
	Segment revenue	$	183,734		$	30,826		$	43,777	$	271,140	$	(900	)	$	528,577
	Purchased product costs	39,710			7,353			15,169		153,628		—			215,860
	Net operating margin	144,024			23,473			28,608		117,512		(900		)	312,717
	Facility expenses	33,755			12,174			8,509		34,354		(900		)	87,892
	Portion of operating income attributable to non-controlling interests	—			4,687			—		6		—			4,693
	Operating income before items not allocated to segments	$	110,269		$	6,612		$	20,099	$	83,152	$	—		$	220,132
	Three months ended June 30, 2013:
		Marcellus			Utica			Northeast		Southwest		Total
	Segment revenue	$	120,057		$	3,594		$	45,365	$	227,842	$	396,858
	Purchased product costs	16,993			—			15,126		123,240		155,359
	Net operating margin	103,064			3,594			30,239		104,602		241,499
	Facility expenses	22,272			6,412			6,655		29,778		65,117
	Portion of operating (loss) income attributable to non-controlling interests	—			(1,143		)	—		53		(1,090		)
	Operating income (loss) before items not allocated to segments	$	80,792		$	(1,675	)	$	23,584	$	74,771	$	177,472
	(1)     Amounts represent revenues and expenses associated with the Northeast segment fractionation completed on behalf of the Marcellus segment, which occurs when NGL volumes in the Marcellus exceed its fractionation capacity.
	The tables below present the Partnership’s segment profit measure, Operating income before items not allocated to segments, and capital expenditures for the six months ended June 30, 2014 and 2013 for the reported segments (in thousands):
	Six months ended June 30, 2014:
		Marcellus			Utica (1)			Northeast		Southwest		Elimination (2)			Total
	Segment revenue	$	358,893		$	54,592		$	105,030	$	530,470	$	(2,471	)	$	1,046,514
	Purchased product costs	74,000			11,488			35,624		306,312		—			427,424
	Net operating margin	284,893			43,104			69,406		224,158		(2,471		)	619,090
	Facility expenses	69,228			24,026			15,623		66,876		(2,471		)	173,282
	Portion of operating income attributable to non-controlling interests	—			7,823			—		5		—			7,828
	Operating income before items not allocated to segments	$	215,665		$	11,255		$	53,783	$	157,277	$	—		$	437,980
	Capital expenditures	$	792,927		$	433,615		$	1,300	$	78,588	$	—		$	1,306,430
	Capital expenditures for Ohio Gathering after deconsolidation (1)														(40,013		)
	Capital expenditures not allocated to segments														8,906
	Total capital expenditures														$	1,275,323
	Six months ended June 30, 2013:
		Marcellus			Utica			Northeast		Southwest		Total
	Segment revenue	$	228,554		$	4,217		$	102,701	$	436,208	$	771,680
	Purchased product costs	35,786			—			34,788		237,342		307,916
	Net operating margin	192,768			4,217			67,913		198,866		463,764
	Facility expenses	44,908			10,374			13,179		58,468		126,929
	Portion of operating (loss) income attributable to non-controlling interests	—			(2,482		)	—		117		(2,365		)
	Operating income (loss) before items not allocated to segments	$	147,860		$	(3,675	)	$	54,734	$	140,281	$	339,200
	Capital expenditures	$	729,040		$	640,819		$	2,509	$	57,816	$	1,430,184
	Capital expenditures not allocated to segments											4,900
	Total capital expenditures											$	1,435,084
	(1)     As disclosed in Note 3, Ohio Gathering was deconsolidated effective June 1, 2014, and its financial position as of June 30, 2014 and results of operations are reported under the equity method of accounting as of June 30, 2014 and for the month of June 2014, respectively. However, the Partnership’s Chief Executive Officer and “chief operating decision maker” continues to view the Utica Segment inclusive of Ohio Gathering, and review its financial information as if they are still combined. The Utica segment includes $40.0 million related to Ohio Gathering capital expenditures after deconsolidation on June 1, 2014 (See Note 3).
	(2)     Amounts represent revenues and expenses associated with the Northeast segment fractionation completed on behalf of the Marcellus segment, which occurs when NGL volumes in the Marcellus exceed its fractionation capacity.
Reconciliation of segment revenue to total revenue and operating income before items not allocated to segments to income before provision for income tax	'
	The following is a reconciliation of segment revenue to total revenue and operating income before items not allocated to segments to income before provision for income tax for the three months ended June 30, 2014 and 2013 (in thousands):
		Three months ended June 30,
		2014			2013
	Total segment revenue	$	528,577		$	396,858
	Derivative (loss) gain not allocated to segments	(6,753		)	19,699
	Revenue adjustment for unconsolidated affiliate (1)	(3,833		)	—
	Revenue deferral adjustment and other (2)	375			(1,437		)
	Total revenue	$	518,366		$	415,120
	Operating income before items not allocated to segments	$	220,132		$	177,472
	Portion of operating income (loss) attributable to non-controlling interests	4,184			(1,090		)
	Derivative (loss) gain not allocated to segments	(20,762		)	39,331
	Revenue adjustment for unconsolidated affiliate (1)	(3,833		)	—
	Revenue deferral adjustment and other (2)	375			(1,437		)
	Compensation expense included in facility expenses not allocated to segments	(903		)	(368		)
	Facility expense and purchase product cost adjustments for unconsolidated affiliate (3)	2,598			—
	Portion of operating loss attributable to non-controlling interests of an unconsolidated affiliate (4)	509			—
	Facility expense adjustments (5)	2,688			2,688
	Selling, general and administrative expenses	(27,701		)	(25,499		)
	Depreciation	(104,078		)	(71,562		)
	Amortization of intangible assets	(15,965		)	(17,092		)
	(Loss) gain on disposal of property, plant and equipment	(1,450		)	37,736
	Accretion of asset retirement obligations	(168		)	(157		)
	Income from operations	55,626			140,022
	Equity in (loss) earnings from unconsolidated affiliates	(721		)	430
	Interest income	10			62
	Interest expense	(43,391		)	(36,955		)
	Amortization of deferred financing costs and debt discount (a component of interest expense)	(1,449		)	(1,784		)
	Miscellaneous income, net	33			6
	Income before provision for income tax	$	10,108		$	101,781
	(1)     Revenue adjustment for unconsolidated affiliate relates to Ohio Gathering revenue for the month of June 2014 (See note above and Note 3).
	(2)     Revenue deferral amount relates primarily to certain contracts in which the cash consideration that the Partnership receives for providing service is greater during the initial years of the contract compared to the later years. In accordance with GAAP, the revenue is recognized evenly over the term of the contract as the Partnership will perform a similar level of service for the entire term. Therefore, the revenue recognized in the current reporting period is less than the cash received. However, the Partnership’s chief operating decision maker and management evaluate the segment performance based on the cash consideration received and therefore, the impact of the revenue deferrals is excluded for segment reporting purposes. For the three months ended June 30, 2014, approximately $0.2 million and $1.5 million of the revenue deferral adjustment is attributable to the Southwest segment and Northeast segment, respectively. In comparison, for the three months ended June 30, 2013, approximately $0.2 million and $1.4 million of the revenue deferral adjustment was attributable to the Southwest segment and Northeast segment, respectively. Beginning in 2015, the cash consideration received from these contracts will decline and the reported segment revenue will be less than the revenue recognized for GAAP purposes. Other consists of management fee revenues from unconsolidated affiliates of $2.1 million for the three months ended June 30, 2014 compared to $0.2 million for three months ended June 30, 2013.
	(3)     Facility expense and purchase product cost adjustments for unconsolidated affiliate consist of the facility expenses and purchase product costs related to Ohio Gathering for the month of June 2014 (See note above and Note 3).
	(4)     Portion of operating loss attributable to non-controlling interests of an unconsolidated affiliate amount relates to Summit’s portion of Ohio Gathering’s operating income, which is included in segment operating income calculation as if Ohio Gathering is consolidated (See note above and Note 3).
	(5)     Facility expenses adjustments consist of the reallocation of the interest expense related to the SMR, which is included in facility expenses for the purposes of evaluating the performance of the Southwest segment.
	The following is a reconciliation of segment revenue to total revenue and operating income before items not allocated to segments to income before provision for income tax for the six months ended June 30, 2014 and 2013 (in thousands):
		Six months ended June 30,
		2014			2013
	Total segment revenue	$	1,046,514		$	771,680
	Derivative (loss) gain not allocated to segments	(10,720		)	19,514
	Revenue adjustment for unconsolidated affiliate (1)	(3,833		)	—
	Revenue deferral adjustment and other (2)	(1,119		)	(2,801		)
	Total revenue	$	1,030,842		$	788,393
	Operating income before items not allocated to segments	$	437,980		$	339,200
	Portion of operating income (loss) attributable to non-controlling interests	7,319			(2,365		)
	Derivative (loss) gain not allocated to segments	(16,663		)	50,182
	Revenue adjustment for unconsolidated affiliate (1)	(3,833		)	—
	Revenue deferral adjustment and other (2)	(1,119		)	(2,801		)
	Compensation expense included in facility expenses not allocated to segments	(1,906		)	(754		)
	Facility expense and purchase product cost adjustments for unconsolidated affiliate (3)	2,598			—
	Portion of operating loss attributable to non-controlling interests of an unconsolidated affiliate (4)	509			—
	Facility expense adjustments (5)	5,376			5,376
	Selling, general and administrative expenses	(62,991		)	(50,741		)
	Depreciation	(206,007		)	(139,579		)
	Amortization of intangible assets	(31,943		)	(31,922		)
	(Loss) gain on disposal of property, plant and equipment	(1,357		)	37,598
	Accretion of asset retirement obligations	(336		)	(509		)
	Income from operations	127,627			203,685
	Equity in (loss) earnings from unconsolidated affiliates	(471		)	665
	Interest income	19			211
	Interest expense	(84,375		)	(75,291		)
	Amortization of deferred financing costs and debt discount (a component of interest expense)	(4,273		)	(3,614		)
	Loss on redemption of debt	—			(38,455		)
	Miscellaneous income, net	43			6
Income before provision for income tax	$	38,570		$	87,207
(1)     Revenue adjustment for unconsolidated affiliate relates to Ohio Gathering revenue for the month of June 2014 (See note above and Note 3).
(2)     Revenue deferral amount relates primarily to certain contracts in which the cash consideration that the Partnership receives for providing service is greater during the initial years of the contract compared to the later years. In accordance with GAAP, the revenue is recognized evenly over the term of the contract as the Partnership will perform a similar level of service for the entire term. Therefore, the revenue recognized in the current reporting period is less than the cash received. However, the Partnership’s chief operating decision maker and management evaluate the segment performance based on the cash consideration received and therefore, the impact of the revenue deferrals is excluded for segment reporting purposes. For the six months ended June 30, 2014, approximately $0.4 million and $3.4 million of the revenue deferral adjustment is attributable to the Southwest segment and Northeast segment, respectively. In comparison, for the six months ended June 30, 2013, approximately $0.4 million and $3.0 million of the revenue deferral adjustment was attributable to the Southwest segment and Northeast segment, respectively. Beginning in 2015, the cash consideration received from these contracts will decline and the reported segment revenue will be less than the revenue recognized for GAAP purposes. Other consists of management fee revenues from unconsolidated affiliates of $2.7 million for the six months ended June 30, 2014 compared to $0.6 million for six months ended June 30, 2013.
(3)     Facility expense and purchase product cost adjustments for unconsolidated affiliate consist of the facility expenses and purchase product costs related to Ohio Gathering for the month of June 2014 (See note above and Note 3).
(4)     Portion of operating loss attributable to non-controlling interests of an unconsolidated affiliate amount relates to Summit’s proportionate share of Ohio Gathering’s operating income, which is included in segment operating income calculation as if Ohio Gathering is consolidated (See note above and Note 3).
(5)     Facility expenses adjustments consist of the reallocation of the interest expense related to the SMR, which is included in facility expenses for the purposes of evaluating the performance of the Southwest segment.
Schedule of assets by segment	'
	The table below presents information about segment assets as of June 30, 2014 and December 31, 2013 (in thousands):
		June 30, 2014			December 31, 2013
	Marcellus	$	5,108,339		$	4,529,028
	Utica (1)	1,882,369			1,646,995
	Northeast	525,743			572,855
	Southwest	2,424,174			2,389,057
	Total segment assets	9,940,625			9,137,935
	Assets not allocated to segments:
	Certain cash and cash equivalents	51,592			63,086
	Fair value of derivatives	5,935			11,962
	Investment in unconsolidated affiliates	71,324			75,627
	Receivables from unconsolidated affiliate	13,977			—
	Other (2)	99,937			107,813
	Total assets	$	10,183,390		$	9,396,423
	(1)     The June 30, 2014 amount excludes assets related to Ohio Gathering, which was deconsolidated on June 1, 2014 and reported as an equity investment as of June 30, 2014 (See note above and Note 3).  This amount includes Utica’s investment in Ohio Gathering.
	(2)     Includes corporate fixed assets, deferred financing costs, income tax receivable, receivables and other corporate assets not allocated to segments.

Supplemental_Condensed_Consoli1

Supplemental Condensed Consolidating Financial Information (Tables)	6 Months Ended
	Jun. 30, 2014
Supplemental Condensed Consolidating Financial Information	'
Schedule of condensed consolidating balance sheets	'
	Condensed Consolidating Balance Sheets
		As of June 30, 2014
		Parent			Guarantor			Non-			Consolidating			Consolidated
					Subsidiaries			Guarantor			Adjustments
								Subsidiaries
	ASSETS
	Current assets:
	Cash and cash equivalents	$	15		$	51,580		$	247,817		$	—		$	299,412
	Restricted cash	—			—			10,000			—			10,000
	Receivables and other current assets	5,094			273,520			138,497			—			417,111
	Intercompany receivables	2,012,956			76,174			67,906			(2,157,036		)	—
	Fair value of derivative instruments	—			4,828			1,107			—			5,935
	Receivables from unconsolidated affiliates	—			1,546			12,431			—			13,977
	Total current assets	2,018,065			407,648			477,758			(2,157,036		)	746,435
	Total property, plant and equipment, net	8,340			2,139,094			5,650,985			(61,531		)	7,736,888
	Other long-term assets:
	Restricted cash	—			—			10,000			—			10,000
	Investment in unconsolidated affiliates	—			81,843			558,603			(10,519		)	629,927
	Investment in consolidated affiliates	5,813,027			5,523,135			—			(11,336,162		)	—
	Intangibles, net of accumulated amortization	—			571,361			270,866			—			842,227
	Intercompany notes receivable	137,000			—			—			(137,000		)	—
	Other long-term assets	49,898			92,065			75,950			—			217,913
	Total assets	$	8,026,330		$	8,815,146		$	7,044,162		$	(13,702,248	)	$	10,183,390
	LIABILITIES AND EQUITY
	Current liabilities:
	Intercompany payables	$	3,109		$	2,074,930		$	78,997		$	(2,157,036	)	$	—
	Fair value of derivative instruments	—			20,288			1,642			—			21,930
	Other current liabilities	58,602			284,191			380,010			(2,262		)	720,541
	Total current liabilities	61,711			2,379,409			460,649			(2,159,298		)	742,471
	Deferred income taxes	3,815			301,710			—			—			305,525
	Long-term intercompany financing payable	—			137,000			96,296			(233,296		)	—
	Fair value of derivative instruments	—			35,668			—			—			35,668
	Long-term debt, net of discounts	3,464,637			—			—			—			3,464,637
	Other long-term liabilities	6,657			148,332			7,839			—			162,828
	Redeemable non-controlling interest	—			—			—			70,711			70,711
	Equity:
	Common Units	3,887,485			5,813,027			6,479,378			(12,265,897		)	3,913,993
	Class B Units	602,025			—			—			—			602,025
	Non-controlling interest in consolidated subsidiaries	—			—			—			885,532			885,532
	Total equity	4,489,510			5,813,027			6,479,378			(11,380,365		)	5,401,550
	Total liabilities and equity	$	8,026,330		$	8,815,146		$	7,044,162		$	(13,702,248	)	$	10,183,390
		As of December 31, 2013
		Parent			Guarantor			Non-			Consolidating			Consolidated
					Subsidiaries			Guarantor			Adjustments
								Subsidiaries
	ASSETS
	Current assets:
	Cash and cash equivalents	$	224		$	79,363		$	5,718		$	—		$	85,305
	Restricted cash	—			—			10,000			—			10,000
	Receivables and other current assets	6,248			266,610			134,880			—			407,738
	Intercompany receivables	1,194,955			78,010			125,115			(1,398,080		)	—
	Fair value of derivative instruments	—			10,444			1,013			—			11,457
	Total current assets	1,201,427			434,427			276,726			(1,398,080		)	514,500
	Total property, plant and equipment, net	5,379			2,149,845			5,622,602			(84,657		)	7,693,169
	Other long-term assets:
	Restricted cash	—			—			10,000			—			10,000
	Investment in unconsolidated affiliates	—			75,627			—			—			75,627
	Investment in consolidated affiliates	5,741,374			4,541,617			—			(10,282,991		)	—
	Intangibles, net of accumulated amortization	—			595,995			278,797			—			874,792
	Fair value of derivative instruments	—			505			—			—			505
	Intercompany notes receivable	151,200			—			—			(151,200		)	—
	Other long-term assets	52,338			92,276			83,216			—			227,830
	Total assets	$	7,151,718		$	7,890,292		$	6,271,341		$	(11,916,928	)	$	9,396,423
LIABILITIES AND EQUITY
Current liabilities:
Intercompany payables	$	—		$	1,315,707		$	82,373		$	(1,398,080	)	$	—
Fair value of derivative instruments	—			26,382			2,456			—			28,838
Other current liabilities	58,110			199,146			583,810			(2,131		)	838,935
Total current liabilities	58,110			1,541,235			668,639			(1,400,211		)	867,773
Deferred income taxes	3,407			284,159			—			—			287,566
Long-term intercompany financing payable	—			151,200			97,461			(248,661		)	—
Fair value of derivative instruments	—			27,763			—			—			27,763
Long-term debt, net of discounts	3,023,071			—			—			—			3,023,071
Other long-term liabilities	3,745			144,561			8,194			—			156,500
Redeemable non-controlling interest	—			—			—			235,617			235,617
Equity:
Common Units	3,461,360			5,741,374			5,497,047			(11,223,486		)	3,476,295
Class B Units	602,025			—			—			—			602,025
Non-controlling interest in consolidated subsidiaries	—			—			—			719,813			719,813
Total equity	4,063,385			5,741,374			5,497,047			(10,503,673		)	4,798,133
Total liabilities and equity	$	7,151,718		$	7,890,292		$	6,271,341		$	(11,916,928	)	$	9,396,423
Schedule of condensed consolidating statements of operations	'
	Condensed Consolidating Statements of Operations
		Three months ended June 30, 2014
		Parent			Guarantor			Non-			Consolidating			Consolidated
					Subsidiaries			Guarantor			Adjustments
								Subsidiaries
	Total revenue	$	—		$	318,408		$	209,800		$	(9,842	)	$	518,366
	Operating expenses:
	Purchased product costs	—			180,638			47,150			—			227,788
	Facility expenses	—			42,567			44,311			(1,288		)	85,590
	Selling, general and administrative expenses	10,760			7,795			12,416			(3,270		)	27,701
	Depreciation and amortization	288			49,719			71,409			(1,373		)	120,043
	Other operating expenses (income)	—			352			6,536			(5,270		)	1,618
	Total operating expenses	11,048			281,071			181,822			(11,201		)	462,740
	(Loss) income from operations	(11,048		)	37,337			27,978			1,359			55,626
	Earnings from consolidated affiliates	54,074			18,928			—			(73,002		)	—
	Other expense, net	(44,526		)	(5,382		)	(4,978		)	9,368			(45,518		)
	Income before provision for income tax	(1,500		)	50,883			23,000			(62,275		)	10,108
	Provision for income tax (benefit) expense	251			(3,191		)	—			—			(2,940		)
	Net income	(1,751		)	54,074			23,000			(62,275		)	13,048
	Net income attributable to non-controlling interest	—			—			—			(4,071		)	(4,071		)
	Net income attributable to the Partnership’s unitholders	$	(1,751	)	$	54,074		$	23,000		$	(66,346	)	$	8,977
		Three months ended June 30, 2013
		Parent			Guarantor			Non-			Consolidating			Consolidated
					Subsidiaries			Guarantor			Adjustments
								Subsidiaries
	Total revenue	$	—		$	298,097		$	126,515		$	(9,492	)	$	415,120
	Operating expenses:
	Purchased product costs	—			117,813			17,114			—			134,927
	Facility expenses	—			34,497			29,485			(385		)	63,597
	Selling, general and administrative expenses	12,074			6,646			8,451			(1,672		)	25,499
	Depreciation and amortization	242			45,457			44,292			(1,337		)	88,654
	Other operating expenses (income)	—			573			(40,233		)	2,081			(37,579		)
	Total operating expenses	12,316			204,986			59,109			(1,313		)	275,098
	(Loss) income from operations	(12,316		)	93,111			67,406			(8,179		)	140,022
	Earnings from consolidated affiliates	132,913			62,611			—			(195,524		)	—
	Other expense, net	(40,102		)	(6,820		)	(2,997		)	11,678			(38,241		)
	Income before provision for income tax	80,495			148,902			64,409			(192,025		)	101,781
	Provision for income tax (benefit) expense	294			15,989			—			—			16,283
	Net income	80,201			132,913			64,409			(192,025		)	85,498
	Net income attributable to non-controlling interest	—			—			—			(1,799		)	(1,799		)
	Net income attributable to the Partnership’s unitholders	$	80,201		$	132,913		$	64,409		$	(193,824	)	$	83,699
		Six months ended June 30, 2014
		Parent			Guarantor			Non-			Consolidating			Consolidated
					Subsidiaries			Guarantor			Adjustments
								Subsidiaries
	Total revenue	$	—		$	643,909		$	408,918		$	(21,985	)	$	1,030,842
	Operating expenses:
	Purchased product costs	—			345,821			85,733			—			431,554
	Facility expenses	—			79,600			92,682			(3,255		)	169,027
	Selling, general and administrative expenses	24,415			18,311			25,765			(5,500		)	62,991
	Depreciation and amortization	568			98,839			141,222			(2,679		)	237,950
	Other operating expenses (income)	—			193			6,770			(5,270		)	1,693
	Total operating expenses	24,983			542,764			352,172			(16,704		)	903,215
	(Loss) income from operations	(24,983		)	101,145			56,746			(5,281		)	127,627
	Earnings from consolidated affiliates	121,784			41,317			—			(163,101		)	—
	Other expense, net	(87,688		)	(11,480		)	(7,934		)	18,045			(89,057		)
	Income before provision for income tax	9,113			130,982			48,812			(150,337		)	38,570
	Provision for income tax (benefit) expense	408			9,198			—			—			9,606
	Net income	8,705			121,784			48,812			(150,337		)	28,964
	Net income attributable to non-controlling interest	—			—			—			(7,495		)	(7,495		)
	Net (loss) income attributable to the Partnership’s unitholders	$	8,705		$	121,784		$	48,812		$	(157,832	)	$	21,469
		Six months ended June 30, 2013
		Parent			Guarantor			Non-			Consolidating			Consolidated
Subsidiaries					Guarantor			Adjustments
					Subsidiaries
Total revenue	$	—		$	569,065		$	235,857		$	(16,529	)	$	788,393
Operating expenses:
Purchased product costs	—			240,763			36,017			—			276,780
Facility expenses	—			66,775			56,387			(387		)	122,775
Selling, general and administrative expenses	24,108			13,619			15,528			(2,514		)	50,741
Depreciation and amortization	519			89,510			84,295			(2,823		)	171,501
Other operating expenses (income)	—			1,338			(40,507		)	2,080			(37,089		)
Total operating expenses	24,627			412,005			151,720			(3,644		)	584,708
(Loss) income from operations	(24,627		)	157,060			84,137			(12,885		)	203,685
Earnings from consolidated affiliates	202,874			81,729			—			(284,603		)	—
Loss on redemption of debt	(38,455		)	—			—			—			(38,455		)
Other expense, net	(83,102		)	(13,236		)	(6,282		)	24,597			(78,023		)
Income before provision for income tax	56,690			225,553			77,855			(272,891		)	87,207
Provision for income tax (benefit) expense	161			22,679			—			—			22,840
Net income	56,529			202,874			77,855			(272,891		)	64,367
Net income attributable to non-controlling interest	—			—			—			3,874			3,874
Net (loss) income attributable to the Partnership’s unitholders	$	56,529		$	202,874		$	77,855		$	(269,017	)	$	68,241
Schedule of condensed consolidating statements of cash flows	'
	Condensed Consolidating Statements of Cash Flows
		Six months ended June 30, 2014
		Parent			Guarantor			Non-			Consolidating			Consolidated
					Subsidiaries			Guarantor			Adjustments
								Subsidiaries
	Net cash (used in) provided by operating activities	$	(97,223	)	$	263,284		$	187,138		$	3,624		$	356,823
	Cash flows from investing activities:
	Capital expenditures	(5,116		)	(108,203		)	(1,157,346		)	(4,658		)	(1,275,323		)
	Equity investments in consolidated affiliates	(30,038		)	(1,090,000		)	—			1,120,038			—
	Investment in unconsolidated affiliates	—			(8,540		)	(67,514		)	—			(76,054		)
	Distributions from consolidated affiliates	63,158			151,110			—			(214,268		)	—
	Investment in intercompany notes, net	14,200			—			—			(14,200		)	—
	Proceeds from disposal of property, plant and equipment	—			4,164			17,398			—			21,562
	Proceeds from sale of equity interest in unconsolidated affiliate	—			—			324,657			—			324,657
	Net cash flows provided by (used in) investing activities	42,204			(1,051,469		)	(882,805		)	886,912			(1,005,158		)
	Cash flows from financing activities:
	Proceeds from public equity offerings, net	711,837			—			—			—			711,837
	Proceeds from Credit Facility	1,923,500			—			—			—			1,923,500
	Payments Credit Facility	(1,482,300		)	—			—			—			(1,482,300		)
	Payments related to intercompany financing, net	—			(14,200		)	(1,034		)	15,234			—
	Payments for debt issue costs and deferred financing costs	(2,045		)	—			—			—			(2,045		)
	Contributions from parent and affiliates	—			30,038			1,090,000			(1,120,038		)	—
	Share-based payment activity	(8,943		)	—			—			—			(8,943		)
	Payment of distributions	(278,316		)	(63,158		)	(151,200		)	214,268			(278,406		)
	Payments of SMR liability	—			(1,201		)	—			—			(1,201		)
	Intercompany advances, net	(808,923		)	808,923			—			—			—
	Net cash flows (used in) provided by financing activities	54,810			760,402			937,766			(890,536		)	862,442
	Net (decrease) increase in cash	(209		)	(27,783		)	242,099			—			214,107
	Cash and cash equivalents at beginning of year	224			79,363			5,718			—			85,305
	Cash and cash equivalents at end of period	$	15		$	51,580		$	247,817		$	—		$	299,412
		Six months ended June 30, 2013
		Parent			Guarantor			Non-			Consolidating			Consolidated
					Subsidiaries			Guarantor			Adjustments
								Subsidiaries
	Net cash (used in) provided by operating activities	$	(79,362	)	$	129,228		$	116,760		$	10,970		$	177,596
	Cash flows from investing activities:
	Restricted cash	—			—			25,500			—			25,500
	Capital expenditures	(480		)	(53,319		)	(1,369,397		)	(11,888		)	(1,435,084		)
	Equity investments in consolidated affiliates	(28,823		)	(783,600		)	—			812,423			—
	Investment in unconsolidated affiliates	—			(8,336		)	—			—			(8,336		)
	Distributions from consolidated affiliates	47,860			389,300			—			(437,160		)	—
	Acquisition of business, net of cash acquired	—			(225,210		)	—			—			(225,210		)
	Proceeds from disposal of property, plant and equipment	—			43			208,066			—			208,109
	Net cash flows provided by (used in) investing activities	18,557			(681,122		)	(1,135,831		)	363,375			(1,435,021		)
	Cash flows from financing activities:
	Proceeds from public equity offerings, net	348,352			—			—			—			348,352
	Proceeds from long-term debt	1,000,000			—			—			—			1,000,000
	Payments of long-term debt	(501,112		)	—			—			—			(501,112		)
	Payments of premiums on redemption of long-term debt	(31,516		)	—			—			—			(31,516		)
	Payments for debt issue costs and deferred financing costs	(14,046		)	—			—			—			(14,046		)
	Payments related to intercompany financing, net	—			—			(918		)	918			—
	Contributions from parent and affiliates	—			28,823			783,600			(812,423		)	—
	Contribution from non-controlling interest	—			—			685,219			—			685,219
	Share-based payment activity	(5,206		)	650			—			—			(4,556		)
	Payment of distributions	(214,903		)	(47,860		)	(389,412		)	437,160			(215,015		)
	Payments of SMR liability	—			(1,103		)	—			—			(1,103		)
	Intercompany advances, net	(595,591		)	595,591			—			—			—
	Net cash flows (used in) provided by financing activities	(14,022		)	576,101			1,078,489			(374,345		)	1,266,223
	Net (decrease) increase in cash	(74,827		)	24,207			59,418			—			8,798
	Cash and cash equivalents at beginning of year	210,015			102,979			32,762			—			345,756
	Cash and cash equivalents at end of period	$	135,188		$	127,186		$	92,180		$	—		$	354,554

Supplemental_Cash_Flow_Informa1

Supplemental Cash Flow Information (Tables)	6 Months Ended
	Jun. 30, 2014
Supplemental Cash Flow Information	'
Schedule of supplemental cash flow information	'
	The following table provides information regarding supplemental cash flow information (in thousands):
		Six months ended June 30,
		2014		2013
	Supplemental disclosures of cash flow information:
	Cash paid for interest, net of amounts capitalized	$	81,031	$	60,835
	Cash received for income taxes, net	321		16,591
	Supplemental schedule of non-cash investing and financing activities:
	Accrued property, plant and equipment	$	312,519	$	524,445
	Interest capitalized on construction in progress	12,679		19,090
	Issuance of common units for vesting of share-based payment awards	7,754		4,495

Variable_Interest_Entity_Detai

Variable Interest Entity (Details) (USD $)

3 Months Ended

6 Months Ended

3 Months Ended

6 Months Ended

1 Months Ended

3 Months Ended

6 Months Ended

0 Months Ended

1 Months Ended

1 Months Ended

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Jul. 31, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

30-May-14

Jan. 31, 2014

Jun. 30, 2014

Jul. 31, 2014

30-May-14

MarkWest Utica EMG

MarkWest Utica EMG

MarkWest Utica EMG

MarkWest Utica EMG

MarkWest Utica EMG

Ohio Gathering

Ohio Gathering

Ohio Gathering

Ohio Gathering

Ohio Gathering

Ohio Gathering

Ohio Gathering

Summit

Summit

Maximum

Summit

Summit

Summit

Summit

Maximum

Subsequent events

Subsequent events

Summit

Variable Interest Entities

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Noncontrolling interest owners total funding commitment

'

'

'

'

$950,000,000

$950,000,000

'

'

'

'

'

'

'

'

'

'

Percentage of capital required by reporting entity after non-controlling interest minimum contribution

'

'

'

'

100.00%

100.00%

'

'

'

'

'

'

'

'

'

'

Aggregate contributions to VIE threshold

'

'

'

'

2,000,000,000

2,000,000,000

'

'

'

'

'

'

'

'

'

'

Percentage of ownership interest in joint venture maximum

'

'

'

'

70.00%

70.00%

'

'

'

'

'

'

'

'

'

'

Minimum Percentage of ownership interest held by non-controlling interest

'

'

'

'

30.00%

30.00%

'

'

'

'

'

'

'

'

'

'

Percentage of capital contribution to maintain ownership percentage

'

'

'

'

'

'

'

'

10.00%

'

'

'

'

'

'

'

Noncontrolling interest owners actual contribution

'

'

'

'

950,000,000

950,000,000

'

'

'

'

'

'

'

'

'

'

Contribution by the Partnership

'

'

'

'

'

944,100,000

'

'

'

'

'

'

'

'

'

'

Noncontrolling interest owners capital contribution preference threshold

'

'

'

'

500,000,000

500,000,000

'

'

'

'

'

'

'

'

'

'

Accrual of preference amount to EMG Utica's investment balance during the period

'

'

'

'

9,100,000

17,900,000

'

'

'

'

'

'

'

'

'

'

Minimum percentage of ownership interest held in joint venture

'

'

'

'

51.00%

51.00%

'

'

'

'

'

'

'

'

'

'

Percentage of available cash to be received by the Partnership

'

'

'

'

60.00%

60.00%

'

'

'

'

'

'

'

'

'

'

Percentage of aggregate investment balances ownership target for the partnership

'

'

'

'

60.00%

60.00%

'

'

'

'

'

'

'

'

'

'

Percentage of ownership interest held by non-controlling interest

'

'

'

'

'

'

'

'

'

'

'

'

'

40.00%

'

1.00%

Cash investment received

'

'

'

'

'

'

'

'

'

'

'

324,700,000

'

'

16,500,000

'

Distributions received from Ohio Gathering

'

'

'

'

'

319,600,000

'

'

'

'

'

'

'

'

'

'

Percentage of ownership interest held in joint venture

'

'

'

'

'

'

'

'

'

'

'

'

1.00%

'

'

'

(Gain) loss on disposal of property, plant and equipment

1,450,000

-37,736,000

1,357,000

-37,598,000

'

'

-5,000,000

-300,000

'

-5,300,000

-5,300,000

'

'

'

'

'

Receivable balance

13,977,000

'

13,977,000

'

'

'

'

'

'

14,000,000

14,000,000

'

'

'

'

'

Management Fees revenue

'

'

'

'

'

'

'

'

'

$1,000,000

$1,000,000

'

'

'

'

'

Other_Equity_Interests_Details

Other Equity Interests (Details) (USD $)

6 Months Ended

3 Months Ended

6 Months Ended

0 Months Ended

1 Months Ended

1 Months Ended

6 Months Ended

6 Months Ended

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Dec. 31, 2013

30-May-14

Jan. 31, 2014

Jun. 30, 2014

Jul. 31, 2014

30-May-14

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Ohio Condensate

Ohio Condensate

EMG

Blackhawk

Summit

Summit

Summit

Summit

Summit

Utica Condensate

Utica Condensate

Utica Condensate

Utica Condensate

Utica Condensate

item

Ohio Condensate

Ohio Condensate

Ohio Condensate

Ohio Condensate

Ohio Condensate

Ohio Condensate

item

Assets under construction

Ohio Condensate

Ohio Condensate

EMG

Subsequent events

Maximum

Other Equity Interests

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Percentage of ownership interest held by non-controlling interest

'

'

'

'

'

1.00%

'

'

40.00%

'

1.00%

45.00%

'

'

'

'

Percentage of capital required by the reporting entity

'

'

'

'

'

'

'

'

'

'

'

100.00%

'

'

'

100.00%

Total capital contribution

'

'

'

'

$125,000,000

'

'

'

'

'

'

'

'

'

'

$100,000,000

Ownership percentage determined under required true up transaction

'

'

'

'

'

'

'

'

'

'

'

55.00%

'

'

'

'

Number of managers consisted in board of managers prior to the condensate equalization date

'

'

'

'

3

'

'

'

'

'

'

3

'

'

'

'

Percentage of ownership interest held by the parent

'

'

'

'

'

'

'

'

'

'

'

'

'

60.00%

99.00%

'

Equity interest acquired (as a percent)

'

'

'

'

'

'

'

1.00%

'

'

'

'

'

'

'

'

Additional equity interest acquired (as a percent)

'

'

'

'

'

'

'

40.00%

'

'

'

'

'

'

'

'

Cash investment received

'

'

'

'

'

'

7,300,000

'

'

1,300,000

'

'

'

'

'

'

Proceeds from sale of assets under construction

21,562,000

208,109,000

'

'

'

'

'

'

'

'

'

'

17,000,000

'

'

'

Management Fees revenue

'

'

$900,000

$1,300,000

'

'

'

'

'

'

'

'

'

'

'

'

Business_Combinations_Details

Business Combinations (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013	8-May-13	8-May-13	8-May-13
			Buffalo Creek Acquisition	Buffalo Creek Acquisition	Buffalo Creek Acquisition
			Chesapeake	Chesapeake	Chesapeake
			mi	Texas	Oklahoma
			acre	mi	mi
Business Combination	'	'	'	'	'
Cash purchase price	'	'	$225,200,000	'	'
Capacity of cryogenic gas processing plant (in MMcf/d)	'	'	200	'	'
Length of gas gathering pipeline (in miles)	'	'	'	22	5
Length of rights-of-way associated with the future construction of a high-pressure trunk line (in miles)	'	'	30	'	'
Area of land (in acres/square miles)	'	'	130,000	'	'
Extended additional term of the keep-whole processing agreement	'	'	'5 years	'	'
Additional cash paid as consideration for extension term of the keep-whole processing agreement	'	'	20,000,000	'	'
Assets:	'	'	'	'	'
Property, plant and equipment	'	'	144,115,000	'	'
Goodwill	144,856,000	144,856,000	2,682,000	'	'
Intangible asset	'	'	84,500,000	'	'
Liabilities:	'	'	'	'	'
Accounts payable	'	'	-6,087,000	'	'
Total	'	'	$225,210,000	'	'

Derivative_Financial_Instrumen2

Derivative Financial Instruments (Details) (USD $)	6 Months Ended
	Jun. 30, 2014
Commodity contracts | Derivative instruments not designated as hedging instruments	'
Derivative financial instruments	'
Notional quantity of crude oil contract (in bbl)	935,540
Notional quantity of natural gas contract (in MMBtu)	1,581,160
Natural Gas Liquids (gal)	83,399,447
Embedded Derivatives in Commodity contracts | Embedded derivative in natural gas processing and purchase contract	'
Derivative financial instruments	'
Notional amount for embedded derivative in commodity contract (in Dth per day)	9,000
Producer's option to extend successive years, number	'5 years
Estimated fair value of embedded derivative contract liability including portion allocable to host processing agreement	$97,838,000
Inception value for period from April 1, 2015 to December 31, 2022	-53,507,000
Recorded value of embedded derivative contract liability	44,331,000
Estimated fair value of embedded derivative contract asset	$1,500,000

Derivative_Financial_Instrumen3

Derivative Financial Instruments (Details 2) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Financial statement impact of derivative contracts	'	'
Assets	$5,935	$11,962
Liabilities	-57,598	-56,601
Derivative instruments not designated as hedging instruments | Commodity contracts	'	'
Financial statement impact of derivative contracts	'	'
Assets	5,935	11,962
Liabilities	-57,598	-56,601
Derivative instruments not designated as hedging instruments | Commodity contracts | Current Assets	'	'
Financial statement impact of derivative contracts	'	'
Assets	5,935	11,457
Derivative instruments not designated as hedging instruments | Commodity contracts | Long-term Assets	'	'
Financial statement impact of derivative contracts	'	'
Assets	'	505
Derivative instruments not designated as hedging instruments | Commodity contracts | Current Liabilities	'	'
Financial statement impact of derivative contracts	'	'
Liabilities	-21,930	-28,838
Derivative instruments not designated as hedging instruments | Commodity contracts | Long-term Liabilities	'	'
Financial statement impact of derivative contracts	'	'
Liabilities	($35,668)	($27,763)

Derivative_Financial_Instrumen4

Derivative Financial Instruments (Details 3) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Assets	'	'
Gross Amounts of Assets in the Consolidated Balance Sheet	$5,935	$11,962
Gross Amounts Not Offset in the Consolidated Balance Sheet	-3,947	-7,017
Net Amount	1,988	4,945
Liabilities	'	'
Gross Amounts of Liabilities in the Consolidated Balance Sheet	-57,598	-56,601
Gross Amounts Not Offset in the Consolidated Balance Sheet	3,947	7,017
Net Amount	-53,651	-49,584
Current Assets	'	'
Assets	'	'
Gross Amounts of Assets in the Consolidated Balance Sheet	5,935	11,457
Gross Amounts Not Offset in the Consolidated Balance Sheet	-3,947	-7,017
Net Amount	1,988	4,440
Non-current Assets	'	'
Assets	'	'
Gross Amounts of Assets in the Consolidated Balance Sheet	'	505
Net Amount	'	505
Current Liabilities	'	'
Liabilities	'	'
Gross Amounts of Liabilities in the Consolidated Balance Sheet	-21,930	-28,838
Gross Amounts Not Offset in the Consolidated Balance Sheet	3,947	7,017
Net Amount	-17,983	-21,821
Non-current Liabilities	'	'
Liabilities	'	'
Gross Amounts of Liabilities in the Consolidated Balance Sheet	-35,668	-27,763
Net Amount	-35,668	-27,763
Commodity contracts | Current Assets	'	'
Assets	'	'
Gross Amounts of Assets in the Consolidated Balance Sheet	4,435	8,181
Gross Amounts Not Offset in the Consolidated Balance Sheet	-3,947	-7,017
Net Amount	488	1,164
Commodity contracts | Non-current Assets	'	'
Assets	'	'
Gross Amounts of Assets in the Consolidated Balance Sheet	'	505
Net Amount	'	505
Commodity contracts | Current Liabilities	'	'
Liabilities	'	'
Gross Amounts of Liabilities in the Consolidated Balance Sheet	-12,045	-18,293
Gross Amounts Not Offset in the Consolidated Balance Sheet	3,947	7,017
Net Amount	-8,098	-11,276
Commodity contracts | Non-current Liabilities	'	'
Liabilities	'	'
Gross Amounts of Liabilities in the Consolidated Balance Sheet	-1,222	'
Net Amount	-1,222	'
Embedded Derivatives in Commodity contracts | Current Assets	'	'
Assets	'	'
Gross Amounts of Assets in the Consolidated Balance Sheet	1,500	3,276
Net Amount	1,500	3,276
Embedded Derivatives in Commodity contracts | Current Liabilities	'	'
Liabilities	'	'
Gross Amounts of Liabilities in the Consolidated Balance Sheet	-9,885	-10,545
Net Amount	-9,885	-10,545
Embedded Derivatives in Commodity contracts | Non-current Liabilities	'	'
Liabilities	'	'
Gross Amounts of Liabilities in the Consolidated Balance Sheet	-34,446	-27,763
Net Amount	($34,446)	($27,763)

Derivative_Financial_Instrumen5

Derivative Financial Instruments (Details 4) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Impact of the Partnership's derivative instruments on Condensed Consolidated Statements of Operations	'	'	'	'
Unrealized (loss) gain	'	'	($7,024)	$46,320
Derivative instruments not designated as hedging instruments	'	'	'	'
Impact of the Partnership's derivative instruments on Condensed Consolidated Statements of Operations	'	'	'	'
Total (loss) gain	-20,762	39,331	-16,663	50,182
Derivative instruments not designated as hedging instruments | Revenue: Derivative (loss) gain	'	'	'	'
Impact of the Partnership's derivative instruments on Condensed Consolidated Statements of Operations	'	'	'	'
Realized (loss) gain	-1,774	3,089	-9,381	6,987
Unrealized (loss) gain	-4,979	16,610	-1,339	12,527
Total (loss) gain	-6,753	19,699	-10,720	19,514
Derivative instruments not designated as hedging instruments | Derivative (loss) gain related to purchased product costs	'	'	'	'
Impact of the Partnership's derivative instruments on Condensed Consolidated Statements of Operations	'	'	'	'
Realized (loss) gain	-144	-1,045	-258	-3,125
Unrealized (loss) gain	-11,820	21,477	-3,908	34,261
Total (loss) gain	-11,964	20,432	-4,166	31,136
Derivative instruments not designated as hedging instruments | Derivative loss related to facility expenses	'	'	'	'
Impact of the Partnership's derivative instruments on Condensed Consolidated Statements of Operations	'	'	'	'
Unrealized (loss) gain	($2,045)	($800)	($1,777)	($468)

Fair_Value_Details

Fair Value (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Derivative instruments carried at fair value in Condensed Consolidated Balance Sheet	'	'
Total carrying value of derivative assets in Condensed Consolidated Balance Sheet	$5,935	$11,962
Total carrying value of derivative liabilities in Condensed Consolidated Balance Sheet	-57,598	-56,601
Recurring | Significant other observable inputs (Level 2) | Commodity contracts	'	'
Derivative instruments carried at fair value in Condensed Consolidated Balance Sheet	'	'
Total carrying value of derivative assets in Condensed Consolidated Balance Sheet	89	544
Total carrying value of derivative liabilities in Condensed Consolidated Balance Sheet	-6,829	-4,691
Recurring | Significant unobservable inputs (Level 3) | Commodity contracts	'	'
Derivative instruments carried at fair value in Condensed Consolidated Balance Sheet	'	'
Total carrying value of derivative assets in Condensed Consolidated Balance Sheet	4,346	8,142
Total carrying value of derivative liabilities in Condensed Consolidated Balance Sheet	-6,438	-13,602
Recurring | Significant unobservable inputs (Level 3) | Embedded Derivatives in Commodity contracts	'	'
Derivative instruments carried at fair value in Condensed Consolidated Balance Sheet	'	'
Total carrying value of derivative assets in Condensed Consolidated Balance Sheet	1,500	3,276
Total carrying value of derivative liabilities in Condensed Consolidated Balance Sheet	($44,331)	($38,308)

Fair_Value_Details_2

Fair Value (Details 2) (Significant unobservable inputs (Level 3), Commodity contracts)	6 Months Ended
	Jun. 30, 2014
Assets | Minimum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities	'
Crude option volatilities (as a percent)	13.89%
Assets | Maximum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities	'
Crude option volatilities (as a percent)	14.93%
Assets | Propane prices | Minimum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities	'
Forward price (in dollars per unit)	1.06
Assets | Propane prices | Maximum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities	'
Forward price (in dollars per unit)	1.09
Assets | Isobutane prices | Minimum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities	'
Forward price (in dollars per unit)	1.34
Assets | Isobutane prices | Maximum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities	'
Forward price (in dollars per unit)	1.36
Assets | Normal butane prices | Minimum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities	'
Forward price (in dollars per unit)	1.26
Assets | Normal butane prices | Maximum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities	'
Forward price (in dollars per unit)	1.31
Assets | Natural gasoline prices | Minimum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities	'
Forward price (in dollars per unit)	2.15
Assets | Natural gasoline prices | Maximum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities	'
Forward price (in dollars per unit)	2.21
Liabilities | Minimum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities	'
Crude option volatilities (as a percent)	8.24%
Liabilities | Maximum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities	'
Crude option volatilities (as a percent)	17.99%
Liabilities | Propane prices | Minimum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities	'
Forward price (in dollars per unit)	1.06
Liabilities | Propane prices | Maximum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities	'
Forward price (in dollars per unit)	1.09
Liabilities | Isobutane prices | Minimum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities	'
Forward price (in dollars per unit)	1.34
Liabilities | Isobutane prices | Maximum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities	'
Forward price (in dollars per unit)	1.36
Liabilities | Normal butane prices | Minimum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities	'
Forward price (in dollars per unit)	1.26
Liabilities | Normal butane prices | Maximum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities	'
Forward price (in dollars per unit)	1.31
Liabilities | Natural gasoline prices | Minimum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities	'
Forward price (in dollars per unit)	2.15
Liabilities | Natural gasoline prices | Maximum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities	'
Forward price (in dollars per unit)	2.21

Fair_Value_Details_3

Fair Value (Details 3) (Significant unobservable inputs (Level 3), Embedded Derivatives in Commodity contracts)	6 Months Ended
	Jun. 30, 2014
	period
Assets | Minimum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets	'
Forward ERCOT Pricing (per Megawatt Hour)	36.16
Assets | Maximum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets	'
Forward ERCOT Pricing (per Megawatt Hour)	52.42
Liabilities	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets	'
Number of renewal periods	2
Term of counterparty option to renew gas purchase agreement	'5 years
Probability of renewal (as a percent)	0.00%
Liabilities | Propane prices | Minimum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets	'
Forward price (in dollars per unit)	1.02
Liabilities | Propane prices | Maximum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets	'
Forward price (in dollars per unit)	1.1
Liabilities | Isobutane prices | Minimum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets	'
Forward price (in dollars per unit)	1.27
Liabilities | Isobutane prices | Maximum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets	'
Forward price (in dollars per unit)	1.38
Liabilities | Normal butane prices | Minimum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets	'
Forward price (in dollars per unit)	1.19
Liabilities | Normal butane prices | Maximum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets	'
Forward price (in dollars per unit)	1.32
Liabilities | Natural gasoline prices | Minimum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets	'
Forward price (in dollars per unit)	1.8
Liabilities | Natural gasoline prices | Maximum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets	'
Forward price (in dollars per unit)	2.21
Liabilities | Natural gas prices | Minimum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets	'
Forward price (in dollars per unit)	3.46
Liabilities | Natural gas prices | Maximum	'
Unobservable inputs used in the valuation of Level 3 instruments of Assets	'
Forward price (in dollars per unit)	5.14

Fair_Value_Details_4

Fair Value (Details 4) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Commodity Derivative Contracts (net)	'	'	'	'
Derivative assets and liabilities classified by the Partnership within Level 3 of the valuation hierarchy	'	'	'	'
Fair value at beginning of period	($751)	$12,477	($5,460)	$12,449
Total gain (loss) (realized and unrealized) included in earnings	-1,961	16,896	-4,238	20,220
Settlements	620	-2,995	7,606	-6,291
Fair value at end of period	-2,092	26,378	-2,092	26,378
The amount of total losses for the period included in earnings attributable to the change in unrealized gains or losses relating to contracts still held at end of period	-1,758	14,755	-1,319	17,854
Embedded Derivatives in Commodity Contracts (net)	'	'	'	'
Derivative assets and liabilities classified by the Partnership within Level 3 of the valuation hierarchy	'	'	'	'
Fair value at beginning of period	-28,486	-24,881	-35,032	-33,957
Total gain (loss) (realized and unrealized) included in earnings	-16,479	20,459	-12,068	26,991
Settlements	2,134	2,019	4,269	4,563
Fair value at end of period	-42,831	-2,403	-42,831	-2,403
The amount of total losses for the period included in earnings attributable to the change in unrealized gains or losses relating to contracts still held at end of period	($15,959)	$20,766	($12,204)	$27,229

Inventories_Details

Inventories (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Inventories	'	'
NGLs	$38,444	$21,131
Line fill	10,466	7,960
Spare parts, materials and supplies	13,825	12,272
Total inventories	$62,735	$41,363

LongTerm_Debt_Details

Long-Term Debt (Details) (USD $)

6 Months Ended

0 Months Ended

6 Months Ended

0 Months Ended

6 Months Ended

Jun. 30, 2014

Jun. 30, 2013

Dec. 31, 2013

Jan. 02, 2015

Mar. 20, 2014

Jun. 30, 2014

Jun. 30, 2014

Mar. 20, 2014

Mar. 31, 2014

Mar. 20, 2014

Mar. 31, 2014

Mar. 20, 2014

Mar. 31, 2014

Mar. 20, 2014

Mar. 31, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Credit Facility

Credit Facility

Credit Facility

Credit Facility

Credit Facility

Credit Facility

Credit Facility

Credit Facility

Credit Facility

Credit Facility

Credit Facility

Credit Facility

Credit Facility

Credit Facility

Credit Facility

Credit facility bearing interest of 4.5%

Credit facility bearing interest of 2.4%

Senior Notes

Senior Notes

2020 Senior Notes, 6.75% interest, issued November 2010 and due November 2020

2020 Senior Notes, 6.75% interest, issued November 2010 and due November 2020

2021 Senior Notes, 6.5% interest, issued February and March 2011 and due August 2021

2021 Senior Notes, 6.5% interest, issued February and March 2011 and due August 2021

2022 Senior Notes, 6.25% interest, issued October 2011 and due June 2022

2022 Senior Notes, 6.25% interest, issued October 2011 and due June 2022

2023A Senior Notes, 5.5% interest, issued August 2012 and due February 2023

2023A Senior Notes, 5.5% interest, issued August 2012 and due February 2023

2023B Senior Notes, 4.5% interest, issued January 2013 and due July 2023

2023B Senior Notes, 4.5% interest, issued January 2013 and due July 2023

LIBO Rate Loans

LIBO Rate Loans

LIBO Rate Loans

LIBO Rate Loans

LIBO Rate Loans

Alternate Base Rate Loans

Alternate Base Rate Loans

Alternate Base Rate Loans

Alternate Base Rate Loans

Prime rate

Federal Funds rate

One month LIBOR

Minimum

Minimum

Maximum

Maximum

Minimum

Minimum

Maximum

Maximum

Long-Term Debt

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Long-term debt, net of discounts

$3,464,637,000

'

$3,023,071,000

'

'

$441,200,000

'

'

'

'

'

'

'

'

'

'

'

'

$166,200,000

$275,000,000

'

'

$500,000,000

$500,000,000

$324,556,000

$324,526,000

$455,000,000

$455,000,000

$743,881,000

$743,545,000

$1,000,000,000

$1,000,000,000

Debt instrument, stated interest rate percentage

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4.50%

2.40%

'

'

6.75%

6.75%

6.50%

6.50%

6.25%

6.25%

5.50%

5.50%

4.50%

4.50%

Long-term debt, discounts

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

444,000

474,000

'

'

6,119,000

6,455,000

'

'

Estimate aggregate fair value of debt

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3,217,000,000

3,079,000,000

'

'

'

'

'

'

'

'

'

'

Credit facility current lending capacity

'

'

'

'

1,300,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Term of debt instrument

'

'

'

'

'18 months

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Accordion option from increase borrowing capacity under the Credit Facility

'

'

'

'

250,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Accordion option to increase borrowing capacity under the Credit Facility

'

'

'

'

500,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Total Leverage Ratio

'

'

'

'

5

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Basis of variable interest rate

'

'

'

'

'

'

'LIBOR

'

'

'

'

'

'

'

'

'Prime rate

'Federal Funds Rate

'One month LIBOR

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Spread on variable rate basis (as a percent)

'

'

'

'

'

'

'

1.50%

1.13%

2.50%

2.00%

0.50%

0.13%

1.50%

1.00%

'

0.50%

1.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Letters of credit maximum borrowing capacity

'

'

'

'

'

150,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Short-term swingline loan maximum borrowing capacity

'

'

'

'

'

10,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Interest Coverage Ratio

'

'

'

'

2.5

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Total leverage ratio before amendment

'

'

'

5.25

5.5

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Deferred financing costs

2,045,000

14,046,000

'

'

'

1,900,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Ownership of the Partnership in its guarantor subsidiaries (as a percent)

100.00%

'

'

'

'

100.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Borrowings outstanding

'

'

'

'

'

441,200,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Letters of credit outstanding amount

'

'

'

'

'

11,300,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Credit facility remaining borrowing capacity

'

'

'

'

'

847,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Amount available for borrowing based on financial covenant requirements

'

'

'

'

'

$645,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Equity_Details

Equity (Details) (USD $)

3 Months Ended

6 Months Ended

3 Months Ended

6 Months Ended

0 Months Ended

0 Months Ended

Jun. 30, 2014

Mar. 31, 2014

Dec. 31, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Jul. 01, 2015

Jul. 01, 2014

Jun. 30, 2014

Mar. 31, 2014

Dec. 31, 2013

Sep. 05, 2013

Mar. 11, 2014

Jun. 30, 2014

Mar. 31, 2014

Dec. 31, 2013

Common Units

Common Units

Common Units

Common Units

Common Units

Class B Units

Class B Units

Maximum

Maximum

Maximum

Maximum

Maximum

Minimum

Minimum

Minimum

September 2013 ATM

March 2014 ATM

March 2014 ATM

M & R

M & R

Common Units

Common Units

Subsequent events

Subsequent events

September 2013 ATM

March 2014 ATM

item

Equity

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Offering under program

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$1,000,000,000

$1,200,000,000

'

'

'

Equity Offerings

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Aggregate common units sold (in units)

'

'

'

'

'

11,284,000

5,720,000

4,200,000

'

7,000,000

'

'

'

'

'

'

'

'

'

'

Proceeds from public equity offerings, net

'

'

'

711,837,000

348,352,000

'

'

272,000,000

440,000,000

440,000,000

'

'

'

'

'

'

'

'

'

'

Manager fees

'

'

'

'

'

'

'

$3,500,000

$3,500,000

$3,500,000

'

'

'

'

'

'

'

'

'

'

Conversion of Class B units to common units (in units)

'

'

'

'

'

'

'

'

'

'

'

4,000,000

'

'

'

'

'

'

'

'

Conversion ratio

'

'

'

'

'

'

'

'

'

'

'

1

'

'

'

'

'

'

'

'

Number of installments

'

'

'

'

'

'

'

'

'

'

3

'

'

'

'

'

'

'

'

'

Number of anniversaries

'

'

'

'

'

'

'

'

'

'

2

'

'

'

'

'

'

'

'

'

Common Unit Price (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

$71.88

$73.42

$75.79

'

'

$58.62

$61.60

$62.56

Distributions of Available Cash

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Distribution per common unit (in dollars per unit)

$0.88

$0.87

$0.86

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Income_Taxes_Details

Income Taxes (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Income Tax	'	'	'	'
Income before provision for income tax	$10,108	$101,781	$38,570	$87,207
Federal income tax at statutory rate	'	'	2,324	18,494
Permanent items	'	'	33	29
State income taxes, net of federal benefit	'	'	577	1,482
Federal and state tax rate change	'	'	4,250	'
Provision on income from Class A units	'	'	2,422	2,835
Total provision for income tax	-2,940	16,283	9,606	22,840
Elimination	'	'	'	'
Income Tax	'	'	'	'
Income before provision for income tax	'	'	-368	-5,655
Federal statutory income tax rate (as a percent)	'	'	0.00%	0.00%
Corporation | Reportable entities	'	'	'	'
Income Tax	'	'	'	'
Income before provision for income tax	'	'	6,641	52,839
Federal statutory income tax rate (as a percent)	'	'	35.00%	35.00%
Federal income tax at statutory rate	'	'	2,324	18,494
Permanent items	'	'	33	29
State income taxes, net of federal benefit	'	'	168	1,321
Federal and state tax rate change	'	'	4,250	'
Provision on income from Class A units	'	'	2,422	2,835
Total provision for income tax	'	'	9,197	22,679
Partnership | Reportable entities	'	'	'	'
Income Tax	'	'	'	'
Income before provision for income tax	'	'	32,297	40,023
Federal statutory income tax rate (as a percent)	'	'	0.00%	0.00%
State income taxes, net of federal benefit	'	'	409	161
Total provision for income tax	'	'	$409	$161

Earnings_Loss_Per_Common_Unit_1

Earnings (Loss) Per Common Unit (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Earnings (Loss) Per Common Unit	'	'	'	'
Net income attributable to the Partnership's unitholders	$8,977	$83,699	$21,469	$68,241
Less: Income allocable to phantom units	551	554	1,096	1,100
Income (loss) available for common unitholders - basic	8,426	83,145	20,373	67,141
Add: Income allocable to phantom units and DER expense	574	569	1,141	1,135
Income (loss) available for common unitholders - diluted	9,000	83,714	21,514	68,276
Weighted average common units outstanding-basic (in units)	164,613	131,227	161,727	129,928
Potential common shares (Class B and phantom units)	16,624	20,639	16,651	20,652
Weighted average common units outstanding-diluted (in units)	181,237	151,866	178,378	150,580
Net income attributable to the Partnership's common unitholders per common unit:	'	'	'	'
Basic (in dollars per unit)	$0.05	$0.63	$0.13	$0.52
Diluted (in dollars per unit)	$0.05	$0.55	$0.12	$0.45
Class B Units	'	'	'	'
Earnings (Loss) Per Common Unit	'	'	'	'
Net income attributable to the Partnership's unitholders	$0	$0	$0	$0
Net income attributable to the Partnership's common unitholders per common unit:	'	'	'	'
Basic (in dollars per unit)	$0	$0	$0	$0
Diluted (in dollars per unit)	$0	$0	$0	$0

Segment_Information_Details

Segment Information (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment information	'	'	'	'
Segment revenue	$525,119	$395,421	$1,041,562	$768,879
Purchased product costs	215,824	155,359	427,388	307,916
Facility expenses	83,545	62,797	167,250	122,307
Income from operations	55,626	140,022	127,627	203,685
Capital expenditures	'	'	1,275,323	1,435,084
Unallocated Segment	'	'	'	'
Segment information	'	'	'	'
Portion of operating income attributable to non-controlling interests	4,184	-1,090	7,319	-2,365
Capital expenditures	'	'	8,906	4,900
Elimination	'	'	'	'
Segment information	'	'	'	'
Segment revenue	-900	'	-2,471	'
Net operating margin	-900	'	-2,471	'
Facility expenses	-900	'	-2,471	'
Total	'	'	'	'
Segment information	'	'	'	'
Segment revenue	528,577	396,858	1,046,514	771,680
Purchased product costs	215,860	155,359	427,424	307,916
Net operating margin	312,717	241,499	619,090	463,764
Facility expenses	87,892	65,117	173,282	126,929
Portion of operating income attributable to non-controlling interests	4,693	-1,090	7,828	-2,365
Income from operations	220,132	177,472	437,980	339,200
Capital expenditures	'	'	1,306,430	1,430,184
Marcellus | Total segments	'	'	'	'
Segment information	'	'	'	'
Segment revenue	183,734	120,057	358,893	228,554
Purchased product costs	39,710	16,993	74,000	35,786
Net operating margin	144,024	103,064	284,893	192,768
Facility expenses	33,755	22,272	69,228	44,908
Income from operations	110,269	80,792	215,665	147,860
Capital expenditures	'	'	792,927	729,040
Utica Segment | Ohio Gathering	'	'	'	'
Segment information	'	'	'	'
Capital expenditures	'	'	-40,013	'
Utica Segment | Total segments	'	'	'	'
Segment information	'	'	'	'
Segment revenue	30,826	3,594	54,592	4,217
Purchased product costs	7,353	'	11,488	'
Net operating margin	23,473	3,594	43,104	4,217
Facility expenses	12,174	6,412	24,026	10,374
Portion of operating income attributable to non-controlling interests	4,687	-1,143	7,823	-2,482
Income from operations	6,612	-1,675	11,255	-3,675
Capital expenditures	'	'	433,615	640,819
Northeast Segment | Total segments	'	'	'	'
Segment information	'	'	'	'
Segment revenue	43,777	45,365	105,030	102,701
Purchased product costs	15,169	15,126	35,624	34,788
Net operating margin	28,608	30,239	69,406	67,913
Facility expenses	8,509	6,655	15,623	13,179
Income from operations	20,099	23,584	53,783	54,734
Capital expenditures	'	'	1,300	2,509
Southwest Segment | Total segments	'	'	'	'
Segment information	'	'	'	'
Segment revenue	271,140	227,842	530,470	436,208
Purchased product costs	153,628	123,240	306,312	237,342
Net operating margin	117,512	104,602	224,158	198,866
Facility expenses	34,354	29,778	66,876	58,468
Portion of operating income attributable to non-controlling interests	6	53	5	117
Income from operations	83,152	74,771	157,277	140,281
Capital expenditures	'	'	$78,588	$57,816

Segment_Information_Details_2

Segment Information (Details 2) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment information	'	'	'	'
Revenue	$525,119	$395,421	$1,041,562	$768,879
Derivative (loss) gain not allocated to segments	-6,753	19,699	-10,720	19,514
Total revenue	518,366	415,120	1,030,842	788,393
Total segments	'	'	'	'
Segment information	'	'	'	'
Revenue	528,577	396,858	1,046,514	771,680
Unallocated Segment	'	'	'	'
Segment information	'	'	'	'
Derivative (loss) gain not allocated to segments	-6,753	19,699	-10,720	19,514
Revenue adjustment for unconsolidated affiliate	-3,833	'	-3,833	'
Revenue deferral adjustment and other	$375	($1,437)	($1,119)	($2,801)

Segment_Information_Details_3

Segment Information (Details 3) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment information	'	'	'	'
Income from operations	$55,626	$140,022	$127,627	$203,685
Selling, general and administrative expenses	-27,701	-25,499	-62,991	-50,741
Depreciation	-104,078	-71,562	-206,007	-139,579
Amortization of intangible assets	-15,965	-17,092	-31,943	-31,922
Loss (gain) on disposal of property, plant and equipment	1,450	-37,736	1,357	-37,598
Accretion of asset retirement obligations	-168	-157	-336	-509
Equity in (loss) earnings from unconsolidated affiliates	-721	430	-471	665
Interest income	10	62	19	211
Interest expense	-43,391	-36,955	-84,375	-75,291
Amortization of deferred financing costs and debt discount (a component of interest expense)	-1,449	-1,784	-4,273	-3,614
Loss on redemption of debt	'	'	'	-38,455
Miscellaneous income, net	33	6	43	6
Income before provision for income tax	10,108	101,781	38,570	87,207
Total segments	'	'	'	'
Segment information	'	'	'	'
Income from operations	220,132	177,472	437,980	339,200
Portion of operating income (loss) attributable to non-controlling interests	4,693	-1,090	7,828	-2,365
Unallocated Segment	'	'	'	'
Segment information	'	'	'	'
Portion of operating income (loss) attributable to non-controlling interests	4,184	-1,090	7,319	-2,365
Derivative (loss) gain not allocated to segments	-20,762	39,331	-16,663	50,182
Revenue adjustment for unconsolidated affiliate	-3,833	'	-3,833	'
Revenue deferral adjustment and other	375	-1,437	-1,119	-2,801
Compensation expense included in facility expenses not allocated to segments	-903	-368	-1,906	-754
Facility expense and purchase product cost adjustments for unconsolidated affiliate	2,598	'	2,598	'
Portion of operating loss attributable to non-controlling interests of an unconsolidated affiliate	509	'	509	'
Facility expense adjustments	2,688	2,688	5,376	5,376
Selling, general and administrative expenses	-27,701	-25,499	-62,991	-50,741
Depreciation	-104,078	-71,562	-206,007	-139,579
Amortization of intangible assets	-15,965	-17,092	-31,943	-31,922
Loss (gain) on disposal of property, plant and equipment	1,450	-37,736	1,357	-37,598
Accretion of asset retirement obligations	-168	-157	-336	-509
Equity in (loss) earnings from unconsolidated affiliates	-721	430	-471	665
Interest income	10	62	19	211
Interest expense	-43,391	-36,955	-84,375	-75,291
Amortization of deferred financing costs and debt discount (a component of interest expense)	-1,449	-1,784	-4,273	-3,614
Loss on redemption of debt	'	'	'	-38,455
Miscellaneous income, net	$33	$6	$43	$6

Segment_Information_Details_4

Segment Information (Details 4) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment information	'	'	'	'
Management fee revenues unconsolidated affiliates	$2,100,000	$200,000	$2,700,000	$600,000
Southwest Segment	'	'	'	'
Segment information	'	'	'	'
Revenue deferral adjustment	200,000	200,000	400,000	400,000
Northeast Segment	'	'	'	'
Segment information	'	'	'	'
Revenue deferral adjustment	$1,500,000	$1,400,000	$3,400,000	$3,000,000

Segment_Information_Details_5

Segment Information (Details 5) (USD $)	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Segment Assets	'	'	'	'
Certain cash and cash equivalents	$299,412	$85,305	$354,554	$345,756
Fair value of derivatives	5,935	11,962	'	'
Investment in unconsolidated affiliates	629,927	75,627	'	'
Receivables from unconsolidated affiliate	13,977	'	'	'
Total assets	10,183,390	9,396,423	'	'
Total segments	'	'	'	'
Segment Assets	'	'	'	'
Total assets	9,940,625	9,137,935	'	'
Unallocated Segment	'	'	'	'
Segment Assets	'	'	'	'
Certain cash and cash equivalents	51,592	63,086	'	'
Fair value of derivatives	5,935	11,962	'	'
Investment in unconsolidated affiliates	71,325	75,627	'	'
Receivables from unconsolidated affiliate	13,977	'	'	'
Other	99,936	107,813	'	'
Marcellus | Total segments	'	'	'	'
Segment Assets	'	'	'	'
Total assets	5,108,339	4,529,028	'	'
Utica Segment | Total segments	'	'	'	'
Segment Assets	'	'	'	'
Total assets	1,882,369	1,646,995	'	'
Northeast Segment | Total segments	'	'	'	'
Segment Assets	'	'	'	'
Total assets	525,743	572,855	'	'
Southwest Segment | Total segments	'	'	'	'
Segment Assets	'	'	'	'
Total assets	$2,424,174	$2,389,057	'	'

Supplemental_Condensed_Consoli2

Supplemental Condensed Consolidating Financial Information (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Supplemental Condensed Consolidating Financial Information	'	'	'	'
Ownership of the Partnership in its guarantor subsidiaries (as a percent)	100.00%	'	'	'
Current assets:	'	'	'	'
Cash and cash equivalents	$299,412	$85,305	$354,554	$345,756
Restricted cash	10,000	10,000	'	'
Receivables and other current assets	417,111	407,738	'	'
Fair value of derivative instruments	5,935	11,457	'	'
Receivables from unconsolidated affiliates	13,977	'	'	'
Total current assets	746,435	514,500	'	'
Total property, plant and equipment, net	7,736,888	7,693,169	'	'
Other long-term assets:	'	'	'	'
Restricted cash	10,000	10,000	'	'
Investment in unconsolidated affiliates	629,927	75,627	'	'
Intangibles, net of accumulated amortization	842,227	874,792	'	'
Fair value of derivative instruments	'	505	'	'
Other long-term assets	217,913	227,830	'	'
Total assets	10,183,390	9,396,423	'	'
Current liabilities:	'	'	'	'
Fair value of derivative instruments	21,930	28,838	'	'
Other current liabilities	720,541	838,935	'	'
Total current liabilities	742,471	867,773	'	'
Deferred income taxes	305,525	287,566	'	'
Fair value of derivative instruments	35,668	27,763	'	'
Long-term debt, net of discounts	3,464,637	3,023,071	'	'
Other long-term liabilities	162,828	156,500	'	'
Redeemable non-controlling interest	70,711	235,617	486,670	'
Equity:	'	'	'	'
Non-controlling interest in consolidated subsidiaries	885,532	719,813	'	'
Total equity	5,401,550	4,798,133	3,482,316	3,111,398
Total liabilities and equity	10,183,390	9,396,423	'	'
Common Units	'	'	'	'
Equity:	'	'	'	'
Common units or Class B units	3,913,993	3,476,295	'	'
Total equity	3,913,993	3,476,295	2,273,759	2,097,404
Class B Units	'	'	'	'
Equity:	'	'	'	'
Common units or Class B units	602,025	602,025	'	'
Total equity	602,025	602,025	752,531	752,531
Reportable legal entities | Parent	'	'	'	'
Current assets:	'	'	'	'
Cash and cash equivalents	15	224	135,188	210,015
Receivables and other current assets	5,094	6,248	'	'
Intercompany receivables	2,012,956	1,194,955	'	'
Total current assets	2,018,065	1,201,427	'	'
Total property, plant and equipment, net	8,340	5,379	'	'
Other long-term assets:	'	'	'	'
Investment in consolidated affiliates	5,813,027	5,741,374	'	'
Intercompany notes receivable	137,000	151,200	'	'
Other long-term assets	49,898	52,338	'	'
Total assets	8,026,330	7,151,718	'	'
Current liabilities:	'	'	'	'
Intercompany payables	3,109	'	'	'
Other current liabilities	58,602	58,110	'	'
Total current liabilities	61,711	58,110	'	'
Deferred income taxes	3,815	3,407	'	'
Long-term debt, net of discounts	3,464,637	3,023,071	'	'
Other long-term liabilities	6,657	3,745	'	'
Equity:	'	'	'	'
Total equity	4,489,510	4,063,385	'	'
Total liabilities and equity	8,026,330	7,151,718	'	'
Reportable legal entities | Parent | Common Units	'	'	'	'
Equity:	'	'	'	'
Common units or Class B units	3,887,485	3,461,360	'	'
Reportable legal entities | Parent | Class B Units	'	'	'	'
Equity:	'	'	'	'
Common units or Class B units	602,025	602,025	'	'
Reportable legal entities | Guarantor Subsidiaries	'	'	'	'
Current assets:	'	'	'	'
Cash and cash equivalents	51,580	79,363	127,186	102,979
Receivables and other current assets	273,520	266,610	'	'
Intercompany receivables	76,174	78,010	'	'
Fair value of derivative instruments	4,828	10,444	'	'
Receivables from unconsolidated affiliates	1,546	'	'	'
Total current assets	407,648	434,427	'	'
Total property, plant and equipment, net	2,139,094	2,149,845	'	'
Other long-term assets:	'	'	'	'
Investment in unconsolidated affiliates	81,843	75,627	'	'
Investment in consolidated affiliates	5,523,135	4,541,617	'	'
Intangibles, net of accumulated amortization	571,361	595,995	'	'
Fair value of derivative instruments	'	505	'	'
Other long-term assets	92,065	92,276	'	'
Total assets	8,815,146	7,890,292	'	'
Current liabilities:	'	'	'	'
Intercompany payables	2,074,930	1,315,707	'	'
Fair value of derivative instruments	20,288	26,382	'	'
Other current liabilities	284,191	199,146	'	'
Total current liabilities	2,379,409	1,541,235	'	'
Deferred income taxes	301,710	284,159	'	'
Long-term intercompany financing payable	137,000	151,200	'	'
Fair value of derivative instruments	35,668	27,763	'	'
Other long-term liabilities	148,332	144,561	'	'
Equity:	'	'	'	'
Total equity	5,813,027	5,741,374	'	'
Total liabilities and equity	8,815,146	7,890,292	'	'
Reportable legal entities | Guarantor Subsidiaries | Common Units	'	'	'	'
Equity:	'	'	'	'
Common units or Class B units	5,813,027	5,741,374	'	'
Reportable legal entities | Non-Guarantor Subsidiaries	'	'	'	'
Current assets:	'	'	'	'
Cash and cash equivalents	247,817	5,718	92,180	32,762
Restricted cash	10,000	10,000	'	'
Receivables and other current assets	138,497	134,880	'	'
Intercompany receivables	67,906	125,115	'	'
Fair value of derivative instruments	1,107	1,013	'	'
Receivables from unconsolidated affiliates	12,431	'	'	'
Total current assets	477,758	276,726	'	'
Total property, plant and equipment, net	5,650,985	5,622,602	'	'
Other long-term assets:	'	'	'	'
Restricted cash	10,000	10,000	'	'
Investment in unconsolidated affiliates	558,603	'	'	'
Intangibles, net of accumulated amortization	270,866	278,797	'	'
Other long-term assets	75,950	83,216	'	'
Total assets	7,044,162	6,271,341	'	'
Current liabilities:	'	'	'	'
Intercompany payables	78,997	82,373	'	'
Fair value of derivative instruments	1,642	2,456	'	'
Other current liabilities	380,010	583,810	'	'
Total current liabilities	460,649	668,639	'	'
Long-term intercompany financing payable	96,296	97,461	'	'
Other long-term liabilities	7,839	8,194	'	'
Equity:	'	'	'	'
Total equity	6,479,378	5,497,047	'	'
Total liabilities and equity	7,044,162	6,271,341	'	'
Reportable legal entities | Non-Guarantor Subsidiaries | Common Units	'	'	'	'
Equity:	'	'	'	'
Common units or Class B units	6,479,378	5,497,047	'	'
Consolidating Adjustments	'	'	'	'
Current assets:	'	'	'	'
Intercompany receivables	-2,157,036	-1,398,080	'	'
Total current assets	-2,157,036	-1,398,080	'	'
Total property, plant and equipment, net	-61,531	-84,657	'	'
Other long-term assets:	'	'	'	'
Investment in unconsolidated affiliates	-10,519	'	'	'
Investment in consolidated affiliates	-11,336,162	-10,282,991	'	'
Intercompany notes receivable	-137,000	-151,200	'	'
Total assets	-13,702,248	-11,916,928	'	'
Current liabilities:	'	'	'	'
Intercompany payables	-2,157,036	-1,398,080	'	'
Other current liabilities	-2,262	-2,131	'	'
Total current liabilities	-2,159,298	-1,400,211	'	'
Long-term intercompany financing payable	-233,296	-248,661	'	'
Redeemable non-controlling interest	70,711	235,617	'	'
Equity:	'	'	'	'
Non-controlling interest in consolidated subsidiaries	885,532	719,813	'	'
Total equity	-11,380,365	-10,503,673	'	'
Total liabilities and equity	-13,702,248	-11,916,928	'	'
Consolidating Adjustments | Common Units	'	'	'	'
Equity:	'	'	'	'
Common units or Class B units	($12,265,897)	($11,223,486)	'	'

Supplemental_Condensed_Consoli3

Supplemental Condensed Consolidating Financial Information (Details 2) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Condensed Consolidating Statements of Operations	'	'	'	'
Total revenue	$518,366	$415,120	$1,030,842	$788,393
Operating expenses:	'	'	'	'
Purchased product costs	227,788	134,927	431,554	276,780
Facility expenses	85,590	63,597	169,027	122,775
Selling, general and administrative expenses	27,701	25,499	62,991	50,741
Depreciation and amortization	120,043	88,654	237,950	171,501
Other operating expenses (income)	1,618	-37,579	1,693	-37,089
Total operating expenses	462,740	275,098	903,215	584,708
Income from operations	55,626	140,022	127,627	203,685
Loss on redemption of debt	'	'	'	-38,455
Other expense, net	-45,518	-38,241	-89,057	-78,023
Income before provision for income tax	10,108	101,781	38,570	87,207
Provision for income tax (benefit) expense	-2,940	16,283	9,606	22,840
Net income	13,048	85,498	28,964	64,367
Net income attributable to non-controlling interest	-4,071	-1,799	-7,495	3,874
Net income attributable to the Partnership's unitholders	8,977	83,699	21,469	68,241
Reportable legal entities | Parent	'	'	'	'
Operating expenses:	'	'	'	'
Selling, general and administrative expenses	10,760	12,074	24,415	24,108
Depreciation and amortization	288	242	568	519
Total operating expenses	11,048	12,316	24,983	24,627
Income from operations	-11,048	-12,316	-24,983	-24,627
Earnings from consolidated affiliates	54,074	132,913	121,784	202,874
Loss on redemption of debt	'	'	'	-38,455
Other expense, net	-44,526	-40,102	-87,688	-83,102
Income before provision for income tax	-1,500	80,495	9,113	56,690
Provision for income tax (benefit) expense	251	294	408	161
Net income	-1,751	80,201	8,705	56,529
Net income attributable to the Partnership's unitholders	-1,751	80,201	8,705	56,529
Reportable legal entities | Guarantor Subsidiaries	'	'	'	'
Condensed Consolidating Statements of Operations	'	'	'	'
Total revenue	318,408	298,097	643,909	569,065
Operating expenses:	'	'	'	'
Purchased product costs	180,638	117,813	345,821	240,763
Facility expenses	42,567	34,497	79,600	66,775
Selling, general and administrative expenses	7,795	6,646	18,311	13,619
Depreciation and amortization	49,719	45,457	98,839	89,510
Other operating expenses (income)	352	573	193	1,338
Total operating expenses	281,071	204,986	542,764	412,005
Income from operations	37,337	93,111	101,145	157,060
Earnings from consolidated affiliates	18,928	62,611	41,317	81,729
Other expense, net	-5,382	-6,820	-11,480	-13,236
Income before provision for income tax	50,883	148,902	130,982	225,553
Provision for income tax (benefit) expense	-3,191	15,989	9,198	22,679
Net income	54,074	132,913	121,784	202,874
Net income attributable to the Partnership's unitholders	54,074	132,913	121,784	202,874
Reportable legal entities | Non-Guarantor Subsidiaries	'	'	'	'
Condensed Consolidating Statements of Operations	'	'	'	'
Total revenue	209,800	126,515	408,918	235,857
Operating expenses:	'	'	'	'
Purchased product costs	47,150	17,114	85,733	36,017
Facility expenses	44,311	29,485	92,682	56,387
Selling, general and administrative expenses	12,416	8,451	25,765	15,528
Depreciation and amortization	71,409	44,292	141,222	84,295
Other operating expenses (income)	6,536	-40,233	6,770	-40,507
Total operating expenses	181,822	59,109	352,172	151,720
Income from operations	27,978	67,406	56,746	84,137
Other expense, net	-4,978	-2,997	-7,934	-6,282
Income before provision for income tax	23,000	64,409	48,812	77,855
Net income	23,000	64,409	48,812	77,855
Net income attributable to the Partnership's unitholders	23,000	64,409	48,812	77,855
Consolidating Adjustments	'	'	'	'
Condensed Consolidating Statements of Operations	'	'	'	'
Total revenue	-9,842	-9,492	-21,985	-16,529
Operating expenses:	'	'	'	'
Facility expenses	-1,288	-385	-3,255	-387
Selling, general and administrative expenses	-3,270	-1,672	-5,500	-2,514
Depreciation and amortization	-1,373	-1,337	-2,679	-2,823
Other operating expenses (income)	-5,270	2,081	-5,270	2,080
Total operating expenses	-11,201	-1,313	-16,704	-3,644
Income from operations	1,359	-8,179	-5,281	-12,885
Earnings from consolidated affiliates	-73,002	-195,524	-163,101	-284,603
Other expense, net	9,368	11,678	18,045	24,597
Income before provision for income tax	-62,275	-192,025	-150,337	-272,891
Net income	-62,275	-192,025	-150,337	-272,891
Net income attributable to non-controlling interest	-4,071	-1,799	-7,495	3,874
Net income attributable to the Partnership's unitholders	($66,346)	($193,824)	($157,832)	($269,017)

Supplemental_Condensed_Consoli4

Supplemental Condensed Consolidating Financial Information (Details 3) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
Condensed Consolidating Statements of Cash Flows	'	'
Net cash (used in) provided by operating activities	$356,823	$177,596
Cash flows from investing activities:	'	'
Restricted cash	'	25,500
Capital expenditures	-1,275,323	-1,435,084
Investment in unconsolidated affiliates	-76,054	-8,336
Acquisition of business, net of cash acquired	'	-225,210
Proceeds from disposal of property, plant and equipment	21,562	208,109
Proceeds from sale of equity interest in unconsolidated affiliate	324,657	'
Net cash flows used in investing activities	-1,005,158	-1,435,021
Cash flows from financing activities:	'	'
Proceeds from public equity offerings, net	711,837	348,352
Proceeds from Credit Facility	1,923,500	'
Payments Credit Facility	-1,482,300	'
Proceeds from long-term debt	'	1,000,000
Payments of long-term debt	'	-501,112
Payments of premiums on redemption of long-term debt	'	-31,516
Payments for debt issue costs and deferred financing costs	-2,045	-14,046
Contribution from non-controlling interest	'	685,219
Share-based payment activity	-8,943	-4,556
Payments of distributions	-278,406	-215,015
Payments of SMR liability	-1,201	-1,103
Net cash flows provided by financing activities	862,442	1,266,223
Net increase in cash and cash equivalents	214,107	8,798
Cash and cash equivalents at beginning of year	85,305	345,756
Cash and cash equivalents at end of period	299,412	354,554
Reportable legal entities | Parent	'	'
Condensed Consolidating Statements of Cash Flows	'	'
Net cash (used in) provided by operating activities	-97,223	-79,362
Cash flows from investing activities:	'	'
Capital expenditures	-5,116	-480
Equity investments in consolidated affiliates	-30,038	-28,823
Distributions from consolidated affiliates	63,158	47,860
Investment in intercompany notes, net	14,200	'
Net cash flows used in investing activities	42,204	18,557
Cash flows from financing activities:	'	'
Proceeds from public equity offerings, net	711,837	348,352
Proceeds from Credit Facility	1,923,500	'
Payments Credit Facility	-1,482,300	'
Proceeds from long-term debt	'	1,000,000
Payments of long-term debt	'	-501,112
Payments of premiums on redemption of long-term debt	'	-31,516
Payments for debt issue costs and deferred financing costs	-2,045	-14,046
Share-based payment activity	-8,943	-5,206
Payments of distributions	-278,316	-214,903
Intercompany advances, net	-808,923	-595,591
Net cash flows provided by financing activities	54,810	-14,022
Net increase in cash and cash equivalents	-209	-74,827
Cash and cash equivalents at beginning of year	224	210,015
Cash and cash equivalents at end of period	15	135,188
Reportable legal entities | Guarantor Subsidiaries	'	'
Condensed Consolidating Statements of Cash Flows	'	'
Net cash (used in) provided by operating activities	263,284	129,228
Cash flows from investing activities:	'	'
Capital expenditures	-108,203	-53,319
Equity investments in consolidated affiliates	-1,090,000	-783,600
Investment in unconsolidated affiliates	-8,540	-8,336
Distributions from consolidated affiliates	151,110	389,300
Acquisition of business, net of cash acquired	'	-225,210
Proceeds from disposal of property, plant and equipment	4,164	43
Net cash flows used in investing activities	-1,051,469	-681,122
Cash flows from financing activities:	'	'
Payments related to intercompany financing, net	-14,200	'
Contributions from Parent and affiliates	30,038	28,823
Share-based payment activity	'	650
Payments of distributions	-63,158	-47,860
Payments of SMR liability	-1,201	-1,103
Intercompany advances, net	808,923	595,591
Net cash flows provided by financing activities	760,402	576,101
Net increase in cash and cash equivalents	-27,783	24,207
Cash and cash equivalents at beginning of year	79,363	102,979
Cash and cash equivalents at end of period	51,580	127,186
Reportable legal entities | Non-Guarantor Subsidiaries	'	'
Condensed Consolidating Statements of Cash Flows	'	'
Net cash (used in) provided by operating activities	187,138	116,760
Cash flows from investing activities:	'	'
Restricted cash	'	25,500
Capital expenditures	-1,157,346	-1,369,397
Investment in unconsolidated affiliates	-67,514	'
Proceeds from disposal of property, plant and equipment	17,398	208,066
Proceeds from sale of equity interest in unconsolidated affiliate	324,657	'
Net cash flows used in investing activities	-882,805	-1,135,831
Cash flows from financing activities:	'	'
Payments related to intercompany financing, net	-1,034	-918
Contributions from Parent and affiliates	1,090,000	783,600
Contribution from non-controlling interest	'	685,219
Payments of distributions	-151,200	-389,412
Net cash flows provided by financing activities	937,766	1,078,489
Net increase in cash and cash equivalents	242,099	59,418
Cash and cash equivalents at beginning of year	5,718	32,762
Cash and cash equivalents at end of period	247,817	92,180
Consolidating Adjustments	'	'
Condensed Consolidating Statements of Cash Flows	'	'
Net cash (used in) provided by operating activities	3,624	10,970
Cash flows from investing activities:	'	'
Capital expenditures	-4,658	-11,888
Equity investments in consolidated affiliates	1,120,038	812,423
Distributions from consolidated affiliates	-214,268	-437,160
Investment in intercompany notes, net	-14,200	'
Net cash flows used in investing activities	886,912	363,375
Cash flows from financing activities:	'	'
Payments related to intercompany financing, net	15,234	918
Contributions from Parent and affiliates	-1,120,038	-812,423
Payments of distributions	214,268	437,160
Net cash flows provided by financing activities	($890,536)	($374,345)

Supplemental_Cash_Flow_Informa2

Supplemental Cash Flow Information (Details) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
Cash paid for interest, net of amounts capitalized	$81,031	$60,835
Cash received for income taxes, net	321	16,591
Supplemental schedule of non-cash investing and financing activities:	'	'
Accrued property, plant and equipment	312,519	524,445
Interest capitalized on construction in progress	12,679	19,090
Issuance of common units for vesting of share-based payment awards	$7,754	$4,495