Third Coast Midstream (AMID) 10-Q 11 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2015	8-May-15	Dec. 31, 2014
Document Information [Line Items]
Entity Registrant Name	American Midstream Partners, LP
Entity Central Index Key	1513965
Document Type	10-Q
Document Period End Date	31-Mar-15
Amendment Flag	FALSE
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	-19
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		22,757,477
Series A convertible preferred, units, outstanding	7,052,000	7,052,207	5,745,000
Series B [Member]
Document Information [Line Items]
Limited partners/ Series B, units outstanding		1,277,772	1,255,000

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (Unaudited) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Current assets
Cash and cash equivalents	$0	$499
Accounts receivable	8,341	4,924
Unbilled revenue	21,104	24,619
Risk management assets	455	688
Other current assets	8,181	15,554
Current deferred tax assets	5,382	3,086
Total current assets	43,463	49,370
Property, plant and equipment, net	606,751	582,182
Goodwill	142,053	142,236
Intangible assets, net	104,692	106,306
Investment in unconsolidated affiliates	21,419	22,252
Other assets, net	14,267	14,298
Total assets	932,645	916,644
Current liabilities
Accounts payable	18,830	20,326
Accrued gas purchases	11,278	14,326
Accrued expenses and other current liabilities	21,284	25,800
Current portion of long-term debt	1,833	2,908
Risk management liabilities	168	215
Total current liabilities	53,393	63,575
Asset retirement obligations	34,762	34,645
Other liabilities	212	126
Long-term debt	386,850	372,950
Deferred tax liabilities	10,652	8,199
Total liabilities	485,869	479,495
Series A convertible preferred units (7,052 thousand and 5,745 thousand units issued and outstanding as of March 31, 2015 and December 31, 2014, respectively)	131,376	107,965
Equity and partners' capital
General Partner Interests (392 thousand units issued and outstanding as of March 31, 2015 and December 31, 2014)	-4,528	-2,450
Accumulated other comprehensive income (loss)	-9	2
Total partners’ capital	310,706	324,467
Noncontrolling interests	4,694	4,717
Total equity and partners' capital	315,400	329,184
Total liabilities, equity and partners' capital	932,645	916,644
Limited Partner Common Units [Member]
Equity and partners' capital
Limited Partner Interests (22,754 thousand and 22,670 thousand units issued and outstanding as of March 31, 2015 and December 31, 2014, respectively)	282,603	294,695
Limited Partner Series B Convertible Units [Member]
Equity and partners' capital
Limited Partner Interests (22,754 thousand and 22,670 thousand units issued and outstanding as of March 31, 2015 and December 31, 2014, respectively)	$32,640	$32,220

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Parenthetical) (Unaudited)	Mar. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Series A convertible preferred, units, issued	7,052,000	5,745,000
Series A convertible preferred, units, outstanding	7,052,000	5,745,000
General partner interest, units issued	392,000	392,000
General partner interest units,outstanding	392,000	392,000
Limited Partner Series B Convertible Units [Member]
Statement of Financial Position [Abstract]
Limited partners/ Series B, units issued	1,278,000	1,255,000
Limited partners/ Series B, units outstanding	1,278,000	1,255,000
Limited Partner Common Units [Member]
Statement of Financial Position [Abstract]
Limited partners/ Series B, units issued	22,754,000	22,670,000
Limited partners/ Series B, units outstanding	22,754,000	22,670,000

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Operations (Unaudited) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Revenue	$64,462	$80,368
Gain (loss) on commodity derivatives, net	147	-130
Total revenue	64,609	80,238
Operating expenses:
Purchases of natural gas, NGLs and condensate	28,978	55,221
Direct operating expenses	13,867	8,961
Selling, general and administrative expenses	6,935	5,593
Equity compensation expense	1,698	360
Depreciation, amortization and accretion expense	9,689	7,632
Total operating expenses	61,167	77,767
Gain (loss) on sale of assets, net	-8	-21
Operating income (loss)	3,434	2,450
Interest expense	-2,610	-1,903
Earnings in unconsolidated affiliates	167	0
Net income (loss) before income tax (expense) benefit	991	547
Income tax (expense) benefit	-156	11
Net income (loss) from continuing operations	835	558
Income (loss) from discontinued operations, net of tax	5	-50
Net income (loss)	840	508
Net income (loss) attributable to noncontrolling interests	14	108
Net income (loss) attributable to the Partnership	826	400
General Partner's Interest in net income (loss)	10
Limited Partners' Interest in net income (loss)	$816
Distribution declared per common unit (a)	$0.47	$0.45
Net income (loss) from continuing operations available to limited partners	($0.19)	($0.32)
Loss from discontinued operations	$0	$0
Net loss	($0.19)	($0.32)
Weighted average number of units used in computation of limited partners’ net (loss) income per unit (basic and diluted)	22,703	9,846

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Comprehensive Income (Unaudited) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Net income (loss)	$840	$508
Unrealized gain (loss) on postretirement benefit plan assets and liabilities	-11	36
Comprehensive income (loss)	829	544
Less: Comprehensive income (loss) attributable to noncontrolling interests	14	108
Comprehensive income (loss) attributable to Partnership	815	436
Accumulated Other Comprehensive Income (Loss) [Member]
Net income (loss)	0	0
Noncontrolling Interest [Member]
Unrealized gain (loss) on postretirement benefit plan assets and liabilities	0	0
Less: Comprehensive income (loss) attributable to noncontrolling interests		$108

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Changes in Partners' Capital (Unaudited) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013
Partners' Capital	$310,706,000		$324,467,000	$73,839,000
Net Income (Loss) Allocated to General Partners	10,000
Net Income (Loss) Allocated to Limited Partners	816,000
Net income (loss)	840,000	508,000
Net Income (Loss) Attributable to Parent	826,000	400,000
Less: Comprehensive income (loss) attributable to noncontrolling interests	14,000	108,000
Less: Comprehensive income attributable to noncontrolling interests	14,000
LTIP vesting		128,000
LTIP tax netting unit repurchase	-725,000	-90,000
Unrealized gain (loss) on postretirement benefit plan assets and liabilities	-11,000	36,000
Partners' Capital	310,706,000		324,467,000	73,839,000
Parent [Member]
Partners' Capital	310,706,000	184,303,000
Net Income (Loss) Attributable to Parent	826,000	400,000
Unitholder contributions	23,000	1,276,000
Unitholder distributions	-15,991,000	-8,561,000
Net distributions to noncontrolling interests	0	0
Acquisition of noncontrolling interests		21,000
LTIP vesting	196,000
LTIP tax netting unit repurchase	-725,000	-90,000
Equity based compensation	1,501,000	328,000
Unrealized gain (loss) on postretirement benefit plan assets and liabilities	-11,000	36,000
Issuance of common units, net of offering costs		86,926,000
Partners' Capital	310,706,000	184,303,000
General Partner [Member]
Partners' Capital	-4,528,000	-3,747,000	-2,450,000	2,696,000
Net Income (Loss) Allocated to General Partners	10,000	7,000
Unitholder contributions	23,000	1,276,000
Unitholder distributions	-1,495,000	-524,000
Issuance and exercise of warrant		-7,164,000
Net distributions to noncontrolling interests	0	0
LTIP vesting	-2,117,000	-366,000
LTIP tax netting unit repurchase	0	0
Equity based compensation	1,501,000	328,000
Unrealized gain (loss) on postretirement benefit plan assets and liabilities	0	0
Issuance of Series B units	0	0
Partners' Capital	-4,528,000	-3,747,000	-2,450,000	2,696,000
Limited Partner [Member]
Partners' Capital	282,603,000	157,910,000	294,695,000	71,039,000
Net Income (Loss) Allocated to Limited Partners	816,000	393,000
Unitholder contributions	0	0
Unitholder distributions	-14,496,000	-8,037,000
Issuance and exercise of warrant		-7,164,000
Net distributions to noncontrolling interests	0	0
Acquisition of noncontrolling interests		21,000
LTIP vesting	2,313,000	494,000
LTIP tax netting unit repurchase	-725,000	-90,000
Equity based compensation	0	0
Unrealized gain (loss) on postretirement benefit plan assets and liabilities	0	0
Issuance of common units, net of offering costs		86,926,000
Issuance of Series B units	0	0
Partners' Capital	282,603,000	157,910,000	294,695,000	71,039,000
Series B [Member]
Partners' Capital	32,640,000	30,000,000	32,220,000	0
Net Income (Loss) Allocated to General Partners		0
Net income (loss)	0	0
Unitholder contributions	0	0
Unitholder distributions	0	0
Net distributions to noncontrolling interests	0	0
LTIP vesting	0	0
LTIP tax netting unit repurchase	0	0
Equity based compensation	0	0
Unrealized gain (loss) on postretirement benefit plan assets and liabilities	0	0
Partners' Capital	32,640,000	30,000,000	32,220,000	0
Accumulated Other Comprehensive Income (Loss) [Member]
Partners' Capital	-9,000	140,000	2,000	104,000
Net income (loss)	0	0
Unitholder contributions	0	0
Unitholder distributions	0	0
Net distributions to noncontrolling interests	0	0
LTIP vesting	0	0
LTIP tax netting unit repurchase	0	0
Equity based compensation	0	0
Partners' Capital	-9,000	140,000	2,000	104,000
Noncontrolling Interest [Member]
Partners' Capital	4,694,000	4,609,000	4,717,000	4,628,000
Less: Comprehensive income (loss) attributable to noncontrolling interests		108,000
Unitholder contributions	0
Net distributions to noncontrolling interests	37,000	98,000
Acquisition of noncontrolling interests		29,000
LTIP vesting	0	0
LTIP tax netting unit repurchase	0	0
Equity based compensation	0	0
Unrealized gain (loss) on postretirement benefit plan assets and liabilities	0	0
Issuance of common units, net of offering costs		0
Partners' Capital	4,694,000	4,609,000	4,717,000	4,628,000
Series B [Member]
Unitholder distributions	-420,000	0
Series B [Member] | Parent [Member]
Issuance of Series B units	420,000	30,000,000
Series B [Member] | Series B [Member]
Issuance of Series B units	420,000	30,000,000
Series B [Member] | Accumulated Other Comprehensive Income (Loss) [Member]
Issuance of Series B units	0	0
Series B [Member] | Noncontrolling Interest [Member]
Issuance of Series B units	$0	$0

Condensed_Consolidated_Stateme3

Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Net income (loss)	$840,000	$508,000
Depreciation, amortization and accretion expense	9,689,000	7,632,000
Amortization of deferred financing costs	338,000	428,000
Amortization of weather derivative premium	241,000	284,000
Unrealized (gain) loss on commodity derivatives, net	-55,000	39,000
Non-cash compensation	1,720,000	360,000
Postretirement expense (benefit)	8,000	12,000
(Gain) loss on sale of assets, net	-8,000	0
Deferred tax expense (benefit)	158,000	-26,000
Accounts receivable	-3,414,000	-1,041,000
Unbilled revenue	3,515,000	-3,222,000
Other current assets	917,000	-2,374,000
Other assets, net	49,000	-15,000
Accounts payable	-151,000	-789,000
Accrued gas purchases	-3,048,000	1,416,000
Accrued expenses and other current liabilities	-1,702,000	263,000
Asset retirement obligations	-83,000	0
Other liabilities	88,000	79,000
Net cash provided by operating activities	9,102,000	3,554,000
Cost of acquisitions, net of cash acquired	183,000	-110,909,000
Additions to property, plant and equipment	-38,922,000	-3,928,000
Proceeds from disposals of property, plant and equipment	2,800,000	6,135,000
Proceeds from Equity Method Investment, Dividends or Distributions, Return of Capital	833,000	0
Restricted cash	6,450,000	0
Net cash used in investing activities	-28,656,000	-108,702,000
PartnersCapitalAccountPublicSaleOfUnitsNetOfOfferingCosts for Cash Flow Disclosure	-148,000	86,926,000
Unitholder contributions	0	1,276,000
Unitholder distributions	-12,159,000	-5,379,000
Issuance of Series A Units	20,000,000	0
Acquisition of noncontrolling interests	0	-8,000
Net distributions to noncontrolling interests	-37,000	-98,000
LTIP tax netting unit repurchase	-725,000	-90,000
Payment of deferred financing costs	-163,000	-144,000
Payments on other debt	-1,613,000	-791,000
Borrowings on other debt	0	170,000
Payments on long-term debt	-54,200,000	-49,771,000
Borrowings on long-term debt	68,100,000	44,686,000
Net cash provided by financing activities	19,055,000	106,777,000
Net increase (decrease) in cash and cash equivalents	-499,000	1,629,000
Beginning of period	499,000
End of period	0	2,022,000
Interest payments, net	2,290,000	1,781,000
Increase (decrease) in accrued property, plant and equipment	3,678,000	1,474,000
Accrued paid in-kind unitholder distributions for Series A Units	3,411,000	1,844,000
In-kind unitholder distributions for Series B Units	420,000	0
Series B [Member]
Issuance of Series A Units	0	30,000,000
Noncontrolling Interest [Member]
LTIP tax netting unit repurchase	$0	$0

Organization_and_Basis_of_Pres

Organization and Basis of Presentation	3 Months Ended
	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	Organization and Basis of Presentation
	General
	American Midstream Partners, LP (the "Partnership", "we", "us", or "our"), was formed on August 20, 2009 as a Delaware limited partnership for the purpose of operating, developing and acquiring a diversified portfolio of midstream energy assets. The Partnership's general partner, American Midstream GP, LLC (the "General Partner"), is 95% owned by High Point Infrastructure Partners, LLC ("HPIP") and 5% owned by AIM Midstream Holdings, LLC. We hold our assets in a series of wholly owned limited liability companies, two limited partnerships and a corporation. Our capital accounts consist of notional general partner units and limited partner interests.
	Nature of Business
	We are engaged in the business of gathering, treating, processing, and transporting natural gas, fractionating NGLs and storing specialty chemical products through our ownership and operation of twelve gathering systems, five processing facilities, three fractionation facilities, four marine terminal sites, three interstate pipelines and five intrastate pipelines. We also own a 66.7% non-operating interest in Main Pass Oil Gathering, LP ("MPOG"), a crude oil gathering and processing system, a 46.0% non-operated interest in Mesquite, an off-spec condensate fractionation project, as well as a 50% undivided, non-operating interest in the Burns Point Plant, a natural gas processing plant. Our primary assets, which are strategically located in Alabama, Georgia, Louisiana, Maryland, Mississippi, North Dakota, Tennessee and Texas, provide critical infrastructure that links producer of natural gas, NGLs, condensate and specialty chemicals to numerous intermediate and end-use markets. We currently operate more than 3,000 miles of pipelines that gather and transport over 1 Bcf/d of natural gas and operate approximately 1.7 million barrels of storage capacity across four marine terminal sites.
	Basis of Presentation
	These unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles ("GAAP") for interim financial information. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. The year-end balance sheet data was derived from consolidated audited financial statements but does not include disclosures required by GAAP for annual periods. We have made reclassifications to amounts reported in prior period condensed consolidated financial statements to conform to our current year presentation. These reclassifications did not have an impact on net income (loss) for the period previously reported. The information furnished herein reflects all normal recurring adjustments that are, in the opinion of management, necessary for a fair statement of financial position and results of operations for the respective interim periods.
	The financial results for the three months ended March 31, 2014, have been reclassified to present an asset group previously presented as held for sale as held and used.
	Our financial results for the three months ended March 31, 2015 are not necessarily indicative of the results that may be expected for the full year ended December 31, 2015. These unaudited condensed consolidated financial statements should be read in conjunction with our consolidated financial statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2014 (“Annual Report”) filed with the Securities and Exchange Commission on March 10, 2015.
	Consolidation Policy
	The accompanying condensed consolidated financial statements include accounts of American Midstream Partners, LP, and its controlled subsidiaries. All significant inter-company accounts and transactions have been eliminated in the preparation of the accompanying condensed consolidated financial statements. We hold a 50% undivided interest in the Burns Point gas processing facility in which we are responsible for our proportionate share of the costs and expenses of the facility. Our condensed consolidated financial statements reflect our proportionate share of the revenues, expenses, assets and liabilities of this undivided interest. As of March 31, 2015, we also hold a 92.2% undivided interest in the Chatom Processing and Fractionation facility (the "Chatom System"). Our condensed consolidated financial statements reflect the accounts of the Chatom System and the interests in the Chatom System held by non-affiliated working interest owners are reflected as noncontrolling interests in the Partnership's condensed consolidated financial statements.
	The Partnership accounts for its 66.7% non-operated interest in MPOG and its 46.0% non-operated interest in Mesquite under the equity method.
	Use of Estimates
	When preparing condensed consolidated financial statements in conformity with GAAP, management must make estimates and assumptions based on information available at the time. These estimates and assumptions affect the reported amounts of assets, liabilities, revenues and expenses, as well as the disclosures of contingent assets and liabilities as of the date of the financial statements. Estimates and assumptions are based on information available at the time such estimates and assumptions are made. Adjustments made with respect to the use of these estimates and assumptions often relate to information not previously available. Uncertainties with respect to such estimates and assumptions are inherent in the preparation of financial statements. Estimates and assumptions are used in, among other things i) estimating unbilled revenues, product purchases and operating and general and administrative costs, ii) developing fair value estimates, including assumptions for future cash flows and discount rates, iii) analyzing long-lived assets, goodwill and intangible assets for possible impairment, iv) estimating the useful lives of assets and v) determining amounts to accrue for contingencies, guarantees and indemnifications. Actual results, therefore, could differ materially from estimated amounts.

Acquisitions_and_Divestitures

Acquisitions and Divestitures	3 Months Ended
	Mar. 31, 2015
Business Combinations [Abstract]
Mergers, Acquisitions and Dispositions Disclosures [Text Block]	Acquisitions and Divestitures
	Costar Acquisition
	On October 14, 2014, the Partnership acquired 100% of the membership interests of Costar Midstream, L.L.C. ("Costar") from Energy Spectrum Partners VI LP and Costar Midstream Energy, LLC, in exchange for $265.2 million in cash and 6.9 million of the Partnership's common units representing Limited Partner interests, or common units (the "Costar Acquisition"). Costar is an onshore gathering and processing company with its primary gathering, processing, fractionation, and off-spec condensate treating and stabilization assets in East Texas and the Permian basin, with a significant crude oil gathering system project under development in the Bakken oil play.
	The Costar Acquisition was accounted for using the acquisition method of accounting and as a result, the aggregate purchase price was allocated to the assets acquired, liabilities assumed and a noncontrolling interest in a Costar subsidiary based on their respective fair values as of the acquisition date. The excess of the aggregate purchase price over the fair values of the assets acquired, liabilities assumed and the noncontrolling interest was classified as goodwill, which is attributable to future prospective customer agreements expected to be obtained as a result of the acquisition. Costar has been included in the Partnership’s Gathering and Processing Segment from the acquisition date.
	The following table summarizes the fair value of consideration transferred to acquire Costar and the allocation of that amount to the assets acquired, liabilities assumed and the noncontrolling interest based upon their respective fair values as of the acquisition date (in thousands).
	Fair value of consideration transferred:
	Cash	$	265,201
	Limited partner common units	147,296
	Total fair value of consideration	$	412,497
	Fair Value of assets acquired, liabilities assumed and noncontrolling interest:
	Working capital	$	8,152
	Property, plant and equipment:
	Processing plants	$	48,357
	Pipelines	128,799
	Land	1,244
	Buildings	682
	Equipment	9,827
	Construction in progress	16,146
	Total property, plant and equipment	205,055
	Investment in unconsolidated affiliate	11,884
	Intangible assets:
	Customer relationships	53,400
	Dedicated acreage	32,000
	Goodwill	102,225
	Noncontrolling interest	(219		)
		$	412,497
	The fair value of the common units of $147.3 million differs from the amount determined using the market price of such units on the date of the acquisition as a result of restrictions which require the sellers to hold the units for specified periods of time. The fair value of limited partner units issued in the transaction was determined using an option pricing model and the following key assumptions: i) the closing unit market price on the day of the acquisition, ii) the contractual holding periods, iii) historical unit price volatility for the Partnership and its peers, and iv) a risk-free rate of return.
	The fair value of property, plant and equipment was determined using both the cost and market approaches which required significant Level 3 inputs. Key assumptions included i) estimated replacement costs for individual assets or asset groups, ii) estimated remaining useful lives for the acquired assets, and iii) recent market transactions for similar assets. The fair value of intangible assets was determined using the income approach which also required significant Level 3 inputs. Key assumptions included i) estimated throughput volumes, ii) forward market prices for natural gas and NGLS as of the acquisition date, iii) estimated future operating and development cash flows, and iv) discount rates ranging from 11.0% to 16.0%.
	The intangible assets acquired relate to existing customer relationships that Costar had at the time of the acquisition, as well as agreements with two producers under which Costar agreed to construct and operate gathering and processing facilities in exchange for the producers’ agreements to dedicate certain acreage and related production to those facilities. Working capital includes $11.2 million of accounts receivable, all of which were subsequently collected. During the first quarter of 2015, we reached final settlement of working capital amounts with the sellers, resulting in an adjustment to goodwill of $0.2 million.
	Costar contributed revenue of $21.4 million and net income of $1.2 million for the three months ended March 31, 2015, attributable to the Partnership's Gathering and Processing segment.
	Lavaca Acquisition
	On January 31, 2014, the Partnership acquired approximately 120 miles of high- and low-pressure pipelines and associated facilities located in the Eagle Ford shale in Gonzales and Lavaca Counties, Texas from Penn Virginia Corporation (NYSE: PVA) ("PVA") for $104.4 million in cash (the "Lavaca Acquisition"). The Lavaca Acquisition was financed with proceeds from the Partnership's January 2014 equity offering and from the issuance of Series B Units to our General Partner.
	The Lavaca Acquisition was accounted for using the acquisition method of accounting and, as a result, the purchase price was allocated to the assets acquired upon their respective fair values as of the acquisition date. The excess of the purchase price over the fair value of the assets acquired was classified as goodwill.
	The following table summarizes the final allocation of the purchase price to the assets acquired based upon their respective fair values as of the acquisition date (in thousands):
	Property, plant and equipment:
	Land	$	2
	Pipelines	58,737
	Equipment	753
	Total property, plant and equipment	59,492
	Intangible assets	21,350
	Goodwill	23,567
	Total cash consideration	$	104,409
	The fair value of property, plant and equipment was determined using the cost approach which required significant Level 3 inputs. Key assumptions included i) estimated replacement costs for individual assets or asset groups and ii) estimated remaining useful lives for the acquired assets. The fair value of intangible assets was determined using the income approach which also required significant Level 3 inputs. Key assumptions included i) estimated throughput volumes, ii) future operating and development cash flows, and iii) a discount rate of 10.5%.
	The intangible assets acquired relate to a gas gathering agreement under which PVA has dedicated certain acreage and related production to the acquired facilities.
	Lavaca contributed revenue of $6.0 million and net income of $2.2 million for the three months ended March 31, 2015, attributable to the Partnership's Gathering and Processing segment.
	Other Acquisitions
	Investment in Unconsolidated Affiliate
	On August 11, 2014, the Partnership acquired a 66.7% non-operated interest in MPOG, an offshore oil gathering system, for a net purchase price of $12.0 million, which was financed with borrowings from the Partnership's credit facility. Although the Partnership owns a majority interest in MPOG, the ownership structure requires unanimous approval of all owners on decisions impacting the operation of the assets and any changes in ownership structure. Therefore, the Partnership's voting rights are not proportional to its obligation to absorb losses or receive returns. The Partnership accounts for its 66.7% interest using the equity method. The Partnership recorded $0.2 million in earnings from unconsolidated affiliate, and received cash distributions of $1.0 million for the three months ended March 31, 2015. The excess of the cash distributions received over the earnings recorded from MPOG is classified as a return of capital within the investing section of our consolidated statement of cash flows.
	Williams Pipeline Acquisition
	In the first quarter of 2014, the Partnership acquired natural gas pipeline facilities that are contiguous to and connect with our High Point System in our Transmission segment located in offshore Louisiana from Transcontinental Gas Pipe Line Company, LLC, a subsidiary of Williams Partners, LP for $6.5 million in cash. The acquisition was subject to FERC approval of the seller's application to abandon by sale to us the pipeline facilities and to permit the facilities to serve a gathering function, exempt from FERC's jurisdiction. The FERC granted approval of the application during the first quarter of 2014, and the purchase and sale agreement closed on March 14, 2014. The purchase price was allocated to pipelines using the income approach which required certain Level 3 inputs.
	Madison Divestiture
	On March 31, 2014, the Partnership completed the sale of certain gathering and processing assets in Madison County, Texas. We received $6.1 million in cash proceeds related to the sale.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Significant Accounting Policies [Text Block]	Recent Accounting Pronouncements
	In April 2014, the FASB issued Accounting Standards Update ("ASU") No. 2014-08, Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity. This guidance amends the requirements for reporting discontinued operations and requires expanded disclosures for individually significant components of an entity that either have been disposed of or are classified as held for sale, but do not qualify for discontinued operations reporting. Only those disposals of components of an entity that represent a strategic shift that has (or will have) a major effect on an entity’s operations and financial results will be reported as discontinued operations in the financial statements. ASU 2014-08 is effective for annual periods, and interim periods within those years, beginning on or after December 15, 2014 and is applied prospectively. Early adoption is permitted, but only for disposals or classifications as held for sale that have not been reported in financial statements previously issued or available for issuance. The update was adopted by the Partnership as of April 1, 2014 and did not have a material impact on its condensed consolidated financial statements.
	In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which amends the existing accounting standards for revenue recognition. The standard requires an entity to recognize revenue in a manner that depicts the transfer of goods or services to customers at an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The guidance in ASU 2014-09 is effective for annual reporting periods beginning after December 15, 2016, including interim periods therein. The FASB voted to propose a deferral of the effective date by one year, but to permit entities to adopt the standard as of the original effective date. The Partnership is currently evaluating the method of adoption and impact this standard will have on its condensed consolidated financial statements and related disclosures.
	In February 2015, the FASB issued ASU No. 2015-02, Amendments to the Consolidation Analysis. This guidance amends the analysis that a reporting entity must perform to determine whether it should consolidate certain types of legal entities. ASU 2015-02 is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2015, and early adoption is permitted. The Partnership is currently evaluating the potential impact this standard will have on its condensed consolidated financial statements and related disclosures.
	In April 2015, the FASB issued ASU No. 2015-03, Simplifying the Presentation of Debt Issuance Costs. This amendment requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. ASU 2015-03 is effective for fiscal years beginning after December 15, 2015, including interim periods therein, and is applied retrospectively. Early adoption is permitted for financial statements that have not been previously issued. At March 31, 2015, the Partnership had $10.5 million of deferred financing costs included in Other assets, net which would be reclassified as a reduction of long-term debt under the updated guidance.
	In April 2015, the FASB issued ASU No. 2015-06, Earnings Per Share (Topic 260).  This guidance clarifies the process for updating historical earnings per unit disclosures when a drop-down transaction occurs between entities under common control.  Pursuant to the amendment, the previously reported earnings per unit measure presented in the historical financial statements would not change as a result of the dropdown transaction.  ASU 2015-06 is effective for annual reporting periods beginning after December 15, 2015, and for interim periods within those fiscal years.  Early adoption is permitted.  The Partnership has evaluated this guidance and determined it is consistent with our policy and historical presentation of earnings per unit.
Summary of Significant Accounting Policies	Debt Obligations
	Our outstanding borrowings under the credit facility were (in thousands):
		March 31,		December 31,
		2015		2014
	Revolving credit facility	$	386,850	$	372,950
	Other debt	1,833		2,908
	Total debt	388,683		375,858
	Less: current portion	1,833		2,908
	Long-term debt	$	386,850	$	372,950
	On September 5, 2014, the Partnership entered into an amended and restated credit agreement (the "Credit Agreement"), which provides for a maximum borrowing equal to $500.0 million, with the ability to further increase the borrowing capacity subject to lender approval. We can elect to have loans under our Credit Agreement bear interest either at a Eurodollar-based rate plus a margin ranging from 2.00% to 3.25% depending on our total leverage ratio then in effect, or a base rate which is a fluctuating rate per annum equal to the highest of (a) the Federal Funds Rate plus 0.50%, (b) the rate of interest in effect for such day as publicly announced from time to time by Bank of America as its “prime rate”, or (c) the Eurodollar Rate plus 1.00% plus a margin ranging from 1.00% to 2.25% depending on the total leverage ratio then in effect. We also pay a maximum commitment fee of 0.50% per annum on the undrawn portion of the revolving loan.
	Our obligations under the Credit Agreement are secured by a first mortgage in favor of the lenders in the majority of our real property. Advances made under the Credit Agreement are guaranteed on a senior unsecured basis by certain of our subsidiaries (the “Guarantors”). These guarantees are full and unconditional and joint and several among the Guarantors. The terms of the Credit Agreement include covenants that restrict our ability to make cash distributions and acquisitions in some circumstances. The remaining principal balance of loans and any accrued and unpaid interest will be due and payable in full on the maturity date, which is September 5, 2019.
	The Credit Agreement contains certain financial covenants, including the requirement that our indebtedness not exceed 4.75 times adjusted consolidated EBITDA (except for the current and subsequent two quarters after the consummation of a permitted acquisition, at which time the covenant is increased to 5.25 times adjusted Consolidated EBITDA) and a minimum interest coverage ratio test (not less than 2.50). The financial covenants in our Credit Agreement may limit the amount available to us for borrowing to less than $500.0 million. In addition to the financial covenants described above, the Credit Agreement also contains customary representations and warranties (including those relating to organization and authorization, compliance with laws, absence of defaults, material agreements and litigation) and customary events of default (including those relating to monetary defaults, covenant defaults, cross defaults and bankruptcy events).
	For the three months ended March 31, 2015 and 2014, the weighted average interest rate on borrowings under the Credit Agreement was approximately 2.37% and 4.40%, respectively.
	As of March 31, 2015, our consolidated total leverage was 4.97 and our interest coverage ratio was 11.06, which were in compliance with the consolidated total leverage ratio and interest coverage ratio tests in accordance with the financial covenants required in the Credit Agreement. At March 31, 2015 and December 31, 2014, letters of credit outstanding under the Credit Agreement were $5.1 million and $1.6 million, respectively.
	Other debt
	Other debt represents insurance premium financing in the original amount of $3.3 million bearing interest at 3.95% per annum, which is repayable in equal monthly installments of approximately $0.4 million through the third quarter of 2015.

Discontinued_Operations_Notes

Discontinued Operations (Notes)	3 Months Ended
	Mar. 31, 2015
Discontinued Operations and Disposal Groups [Abstract]
Disposal Groups, Including Discontinued Operations, Disclosure [Text Block]	Discontinued Operations
	The Partnership continues to classify the terminal asset in Salisbury, Maryland as held for sale as we are continuing negotiations for the sale of those assets, contingent upon the purchaser’s completion of due diligence. The net book value of the assets and liabilities attributable to the terminal asset comprise less than $0.1 million of Other current assets, $1.2 million of Other assets, net, and less than $0.1 million of Accrued expenses and other current liabilities as of March 31, 2015 and December 31, 2014.
	We have classified these assets as discontinued operations within our condensed consolidated statement of operations. Accordingly, we reclassified and excluded the disposal group's results of operations from our results of continuing operations and reported the disposal group's results of operations as Income (loss) from discontinued operations, net of tax in our accompanying condensed consolidated statement of operations for all periods presented. We did not, however, elect to present separately the operating, investing and financing cash flows related to the disposal groups in our accompanying condensed consolidated statement of cash flows as this activity was immaterial for all periods presented. The following table presents the revenue, expense and gain (loss) from operations of disposal groups associated with the assets classified as held for sale for the three months ended March 31, 2015 and 2014 (in thousands, except per unit amounts):
		Three months ended March 31,
		2015			2014
	Revenue	$	64		$	237
	Expense	(55		)	(277		)
	Loss on sale of assets	—			(22		)
	Income tax benefit	(4		)	12
	Income (loss) from operations of disposal groups, net of tax	$	5		$	(50	)
	Limited partners' net income (loss) per unit from discontinued operations (basic and diluted)	$	—		$	—

Concentration_of_Credit_Risk_a

Concentration of Credit Risk and Trade Accounts Receivable	3 Months Ended
	Mar. 31, 2015
Risks and Uncertainties [Abstract]
Concentration Risk Disclosure [Text Block]	Concentration of Credit Risk and Trade Accounts Receivable
	Our primary assets, which are strategically located in Alabama, Georgia, Louisiana, Maryland, Mississippi, North Dakota, Tennessee and Texas, provide critical infrastructure that links customers of natural gas, NGLs, condensate and specialty chemicals to numerous intermediate and end-use markets.  As a result of recent acquisitions and geographic diversification, we have reduced the concentration of trade receivable balances due from these customer groups, and as such reduced the concentration which may affect our overall credit risk in that the customers may be similarly affected by changes in economic, regulatory or other factors. We maintain allowances for potentially uncollectible accounts receivable; however, for the three months ended March 31, 2015 and 2014, no allowances on or significant write-offs of accounts receivable were recorded.
	The following table summarizes the percentage of revenue earned from those customers that accounted for 10% or more of the Partnership's consolidated revenue in its condensed consolidated statement of operations for each of the periods presented below:
		Three months ended March 31,
		2015		2014
	Customer A	10	%	12	%
	Customer B	—	%	30	%
	Customer C	—	%	15	%
	Other	90	%	43	%
	Total	100	%	100	%

Other_Current_Assets_Notes

Other Current Assets (Notes)	3 Months Ended
	Mar. 31, 2015
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Schedule of Other Current Assets	Other current assets consist of the following (in thousands):
		March 31,		December 31,
		2015		2014
	Prepaid insurance	$	2,845	$	4,162
	Restricted cash	25		6,475
	Other current assets	5,311		4,917
		$	8,181	$	15,554

Derivatives

Derivatives	3 Months Ended
	Mar. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives	Derivatives
	Commodity Derivatives
	To minimize the effect of commodity price changes and maintain our cash flow and the economics of our development plans, we enter into commodity hedge contracts from time to time. The terms of the contracts depend on various factors, including management's view of future commodity prices, economics on purchased assets and future financial commitments. This hedging program is designed to mitigate the effect of commodity price declines while allowing us to participate in some commodity price upside. Management regularly monitors the commodity markets and financial commitments to determine if, when, and at what level commodity hedging is appropriate in accordance with policies that are established by the board of directors of our General Partner. Currently, our commodity derivatives are in the form of swaps and collars. As of March 31, 2015, the aggregate notional volume of our commodity derivatives was 2.7 million gallons.
	We enter into commodity contracts with multiple counterparties, and in some cases, may be required to post collateral with our counterparties in connection with our derivative positions. As of March 31, 2015, we were not required to post collateral with any counterparty. The counterparties are not required to post collateral with us in connection with their derivative positions. Netting agreements are in place that permit us to offset our commodity derivative asset and liability positions with our counterparties.
	We did not designate any of our commodity derivatives as hedges for accounting purposes. As a result, our commodity derivatives are accounted for at fair value in our condensed consolidated balance sheets with changes in fair value recognized currently in earnings.
	Interest Rate Swap
	We entered into an interest rate swap to manage the impact of the interest rate risk associated with our credit facility, effectively converting a portion of the cash flows related to our long-term variable rate debt into fixed rate cash flows. As of March 31, 2015, the notional amount of our interest rate swap was $100.0 million. The interest rate swap was entered into with a single counterparty and we were not required to post collateral. The interest rate swap will expire August 1, 2015.
	Weather Derivative
	In the second quarter of 2014, we entered into a weather derivative to mitigate the impact of potential unfavorable weather to our operations under which we could receive payments totaling up to $10.0 million in the event that a hurricane or hurricanes of certain strength pass through the area as identified in the derivative agreement. The weather derivatives are accounted for using the intrinsic value method, under which the fair value of the contract was zero and any amounts received are recognized as gains during the period received. The weather derivatives were entered into with a single counterparty and we were not required to post collateral.
	We paid premiums of $1.0 million in 2014, which are recorded as current Risk management assets on our condensed consolidated balance sheet and are being amortized to Direct operating expenses on a straight-line basis over the term of the contract of one year. Unamortized amounts associated with the weather derivatives were approximately $0.2 million as of March 31, 2015 and 2014.
	As of March 31, 2015 and December 31, 2014, the value associated with our commodity derivatives, interest rate swap, and weather derivative were recorded in our condensed consolidated balance sheets, under the captions as follows (in thousands):
			Gross Risk Management Assets					Gross Risk Management Liabilities						Net Risk Management Assets (Liabilities)
	Balance Sheet Classification		March 31,			December 31, 2014		March 31,			December 31, 2014			March 31,			December 31, 2014
			2015					2015						2015
	Current		$	455		$	688	$	—		$	—		$	455		$	688
	Noncurrent		—			—		—			—			—			—
	Total assets		$	455		$	688	$	—		$	—		$	455		$	688
	Current		$	—		$	—	$	(168	)	$	(215	)	$	(168	)	$	(215	)
	Noncurrent		—			—		—			—			—			—
	Total liabilities		$	—		$	—	$	(168	)	$	(215	)	$	(168	)	$	(215	)
	For the three months ended March 31, 2015 and 2014, respectively, the realized and unrealized gains (losses) associated with our commodity derivatives, interest rate swap instrument and weather derivative were recorded in our condensed consolidated statements of operations, under the captions as follows (in thousands):
		Three months ended March 31,
		Gain (loss) on derivatives
	Statement of Operations Classification	Realized			Unrealized
	2015
	Gain (loss) on commodity derivatives, net	$	139		$	8
	Interest expense	(102		)	47
	Direct operating expenses	(241		)	—
	Total	$	(204	)	$	55
	2014
	Gain (loss) on commodity derivatives, net	$	(102	)	$	(28	)
	Interest expense	(104		)	(11		)
	Direct operating expenses	(284		)	—
	Total	$	(490	)	$	(39	)

Fair_Value_Measurement

Fair Value Measurement	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurement	Fair Value Measurement
	We believe the carrying amount of cash and cash equivalents, accounts receivable and accounts payable approximates fair value because of the short-term maturity of these instruments.
	The recorded value of the amounts outstanding under the credit facility approximates its fair value, as interest rates are variable, based on prevailing market rates and the short-term nature of borrowings and repayments under the credit facility.
	The fair value of all derivatives instruments is estimated using a market valuation methodology based upon forward commodity price curves, volatility curves as well as other relevant economic measures, if necessary. Discount factors may be utilized to extrapolate a forecast of future cash flows associated with long dated transactions or illiquid market points. The inputs are obtained from independent pricing services, and we have made no adjustments to the obtained prices.
	We have consistently applied these valuation techniques in all periods presented and believe we have obtained the most accurate information available for the types of derivatives contracts held. We will recognize transfers between levels at the end of the reporting period in which the transfer occurred. There were no such transfers for the three months ended March 31, 2015 and 2014.
	Fair Value of Financial Instruments
	The following table sets forth by level within the fair value hierarchy, our commodity derivative instruments and interest rate swap, included as part of Risk management assets and Risk management liabilities within our condensed consolidated balance sheets, that were measured at fair value on a recurring basis as of March 31, 2015 and December 31, 2014 (in thousands):
		Carrying			Estimated Fair Value of the Asset (Liability)
		Amount			Level 1		Level 2			Level 3		Total
	Commodity derivative instruments, net
	March 31, 2015	$	294		$	—	$	294		$	—	$	294
	December 31, 2014	286			—		286			—		286
	Interest rate swap
	31-Mar-15	$	(168	)	$	—	$	(168	)	$	—	$	(168	)
	31-Dec-14	(215		)	—		(215		)	—		(215		)
	The unamortized portion of the premium paid to enter the weather derivative described in Note 7 "Derivatives" is included within Risk management assets on our condensed consolidated balance sheet but is not included as part of the above table as it is recorded at amortized carrying cost, not fair value.

Property_Plant_and_Equipment

Property, Plant and Equipment	3 Months Ended
	Mar. 31, 2015
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, Plant and Equipment, Net
	Property, plant and equipment, net, as of March 31, 2015 and December 31, 2014 were as follows (in thousands):
		Useful Life	March 31,			December 31,
		(in years)	2015			2014
	Land	N/A	$	5,282		$	5,282
	Construction in progress	N/A	101,263			77,550
	Base gas	N/A	1,108			1,108
	Buildings and improvements	4 to 40	7,252			6,855
	Processing and treating plants	8 to 40	80,838			80,837
	Pipelines	3 to 40	458,732			451,341
	Compressors	4 to 20	25,403			24,548
	Dock	20 to 40	8,072			8,072
	Tanks, truck rack and piping	20 to 40	30,155			30,079
	Equipment	8 to 20	8,860			8,855
	Computer software	5	3,490			3,490
	Total property, plant and equipment		730,455			698,017
	Accumulated depreciation		(123,704		)	(115,835		)
	Property, plant and equipment, net		$	606,751		$	582,182
	Of the gross property, plant and equipment balances at March 31, 2015 and December 31, 2014, $102.8 million and $101.9 million, respectively, were related to AlaTenn, Midla and HPGT, our FERC regulated interstate and intrastate assets.
	Capitalized interest was $0.2 million and $0.1 million for the three months ended March 31, 2015 and 2014, respectively.
	Depreciation expense was $7.9 million and $6.5 million for the three months ended March 31, 2015 and 2014, respectively.

Goodwill_and_Intangible_Assets

Goodwill and Intangible Assets, Net (Notes)	3 Months Ended
	Mar. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets, Net	Goodwill and Intangible Assets, Net
	The carrying value of goodwill as of March 31, 2015 and December 31, 2014, was $142.1 million and $142.2 million, respectively. During the first quarter of 2015, we reached final settlement of working capital amounts associated with the Costar Acquisition, resulting in an adjustment to goodwill of $0.2 million. Goodwill as of March 31, 2015 consisted of $125.8 million and $16.3 million related to our Gathering and Processing and Terminal Segments, respectively. Goodwill as of December 31, 2014 consisted of $125.9 million and $16.3 million related to our Gathering and Processing and Terminal Segments, respectively.
	The goodwill associated with our Gathering and Processing segment relates to the Costar and Lavaca Acquisitions and primarily represent strategic developmental locations to grow the business within the segment. The goodwill associated with our Terminal Segment was contributed to the Partnership as part of the Partnerships' acquisition of Blackwater Midstream Holdings LLC ("Blackwater") and other related subsidiaries from an affiliate of HPIP (the "Blackwater Acquisition"). Goodwill was recorded as a result of the excess of the investment by an affiliate of HPIP in Blackwater over the fair market value of the identifiable net assets and customer contracts acquired.
	Intangible assets, net, consists of customer contracts, relationships and dedicated acreage agreements identified as part of the Costar Acquisition, Lavaca Acquisition and Blackwater Acquisition. These intangible assets have definite lives and are subject to amortization on a straight-line basis over their economic lives, currently ranging from 5 months to thirty years. Intangible assets, net, consist of the following (in thousands):
		March 31,			December 31,
		2015			2014
	Gross carrying amount:
	Customer contracts	$	12,101		$	12,101
	Customer relationships	53,400			53,400
	Dedicated acreage	53,350			53,350
		$	118,851		$	118,851
	Accumulated amortization:
	Customer contracts	$	(11,636	)	$	(11,110	)
	Customer relationships	(1,197		)	(553		)
	Dedicated acreage	(1,326		)	(882		)
		$	(14,159	)	$	(12,545	)
	Net carrying amount:
	Customer contracts	$	465		$	991
	Customer relationships	52,203			52,847
	Dedicated acreage	52,024			52,468
		$	104,692		$	106,306
	For the three months ended March 31, 2015 and 2014, amortization expense on our intangible assets totaled $1.6 million and $0.7 million, respectively.

Accrued_Expenses_and_Other_Cur

Accrued Expenses and Other Current Liabilities (Notes)	3 Months Ended
	Mar. 31, 2015
Other Liabilities Disclosure [Abstract]
Accrued Expenses and Other Current Liabilities	Accrued Expenses and Other Current Liabilities
	Accrued expenses and other current liabilities were as follows (in thousands):
		March 31,		December 31,
		2015		2014
	Accrued capital expenditures	$	15,403	$	17,134
	Accrued expenses	1,249		7,036
	Gas imbalances payable	967		1,069
	Other	3,665		561
		$	21,284	$	25,800

Debt_Obligations

Debt Obligations	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Debt Obligations	Debt Obligations
	Our outstanding borrowings under the credit facility were (in thousands):
		March 31,		December 31,
		2015		2014
	Revolving credit facility	$	386,850	$	372,950
	Other debt	1,833		2,908
	Total debt	388,683		375,858
	Less: current portion	1,833		2,908
	Long-term debt	$	386,850	$	372,950
	On September 5, 2014, the Partnership entered into an amended and restated credit agreement (the "Credit Agreement"), which provides for a maximum borrowing equal to $500.0 million, with the ability to further increase the borrowing capacity subject to lender approval. We can elect to have loans under our Credit Agreement bear interest either at a Eurodollar-based rate plus a margin ranging from 2.00% to 3.25% depending on our total leverage ratio then in effect, or a base rate which is a fluctuating rate per annum equal to the highest of (a) the Federal Funds Rate plus 0.50%, (b) the rate of interest in effect for such day as publicly announced from time to time by Bank of America as its “prime rate”, or (c) the Eurodollar Rate plus 1.00% plus a margin ranging from 1.00% to 2.25% depending on the total leverage ratio then in effect. We also pay a maximum commitment fee of 0.50% per annum on the undrawn portion of the revolving loan.
	Our obligations under the Credit Agreement are secured by a first mortgage in favor of the lenders in the majority of our real property. Advances made under the Credit Agreement are guaranteed on a senior unsecured basis by certain of our subsidiaries (the “Guarantors”). These guarantees are full and unconditional and joint and several among the Guarantors. The terms of the Credit Agreement include covenants that restrict our ability to make cash distributions and acquisitions in some circumstances. The remaining principal balance of loans and any accrued and unpaid interest will be due and payable in full on the maturity date, which is September 5, 2019.
	The Credit Agreement contains certain financial covenants, including the requirement that our indebtedness not exceed 4.75 times adjusted consolidated EBITDA (except for the current and subsequent two quarters after the consummation of a permitted acquisition, at which time the covenant is increased to 5.25 times adjusted Consolidated EBITDA) and a minimum interest coverage ratio test (not less than 2.50). The financial covenants in our Credit Agreement may limit the amount available to us for borrowing to less than $500.0 million. In addition to the financial covenants described above, the Credit Agreement also contains customary representations and warranties (including those relating to organization and authorization, compliance with laws, absence of defaults, material agreements and litigation) and customary events of default (including those relating to monetary defaults, covenant defaults, cross defaults and bankruptcy events).
	For the three months ended March 31, 2015 and 2014, the weighted average interest rate on borrowings under the Credit Agreement was approximately 2.37% and 4.40%, respectively.
	As of March 31, 2015, our consolidated total leverage was 4.97 and our interest coverage ratio was 11.06, which were in compliance with the consolidated total leverage ratio and interest coverage ratio tests in accordance with the financial covenants required in the Credit Agreement. At March 31, 2015 and December 31, 2014, letters of credit outstanding under the Credit Agreement were $5.1 million and $1.6 million, respectively.
	Other debt
	Other debt represents insurance premium financing in the original amount of $3.3 million bearing interest at 3.95% per annum, which is repayable in equal monthly installments of approximately $0.4 million through the third quarter of 2015.

Partners_Capital

Partners' Capital	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
Partners' Capital	Partners’ Capital and Convertible Preferred Units
	Our capital accounts are comprised of approximately 1.3% notional general partner interests and 98.7% limited partner interests. Our limited partners have limited rights of ownership as provided for under our partnership agreement and the right to participate in our distributions. Our General Partner manages our operations and participates in our distributions, including certain incentive distributions pursuant to the incentive distribution rights that are non-voting limited partner rights held by our General Partner.
	Our General Partner holds and participates in the distribution of Series B Units with such distributions being made in cash or with paid-in-kind Series B Units at the election of the Partnership. The holders of Series B Units are entitled to vote along with the holders of Limited Partner common units and such units will automatically convert to Limited Partner common units on January 31, 2016.
	HPIP holds and participates in the distribution of Series A-1 Units with such distributions being made in paid-in-kind Series A-1 Units, cash or a combination thereof, at the election of the board of directors of our General Partner through the distribution for the earlier of (a) the quarter ended March 31, 2016 or (b) the time in which the Series A-1 Units are converted into common units. The Series A-1 Units are entitled to vote along with Limited Partner common unitholders and such units are currently convertible to Limited Partner common units.
	Series A-2 Units
	On March 30, 2015, we entered into a Series A-2 Convertible Preferred Unit Purchase Agreement (the "Agreement") with Magnolia Infrastructure Partners, LLC (an affiliate of HPIP) pursuant to which the Partnership issued in a private placement newly-designated Series A-2 Units (the “Series A-2 Units”) representing limited partnership interests in the Partnership for approximately $20.0 million in aggregate proceeds. Under the Agreement, the Partnership has the ability to issue additional Series A-2 Units for up $25 million in aggregate proceeds. The Series A-2 Units will participate in distributions of the Partnership along with common units in a manner identical to the existing Series A Units, with such distributions being made in cash or with paid-in-kind Series A Units at the election of the Partnership (the Series A-1 Units and the Series A-2 Units are herein collectively referred to as the Series A Units). The Partnership has elected to pay Series A distributions using paid-in-kind Series A Units.
	Equity Offerings
	On January 29, 2014, the Partnership and certain of its affiliates entered into an underwriting agreement with Barclays Capital Inc. and UBS Securities LLC (the “Underwriters”), providing for the issuance and sale by the Partnership, and the purchase by the Underwriter, of 3,400,000 Limited Partner common units representing limited partner interests in the Partnership at a price to the public of $26.75 per common unit. The Partnership used the net proceeds of $86.9 million to fund a portion of the Lavaca Acquisition.
	Issuance and Exercise of Warrant
	Effective February 5, 2014, we issued to AIM Midstream Holdings, LLC a warrant to purchase up to 300,000 Limited Partner common units of the Partnership at an exercise price of $0.01 per common unit (the “Warrant”). The Warrant was exercised on February 21, 2014, resulting in the issuance of approximately 300,000 Limited Partner common units. The value of the Warrant of $7.2 million was determined based on the close price of $23.89 of the Limited Partner common units on the exercise date.
	Equity Outstanding
	The number of units outstanding as of March 31, 2015 and December 31, 2014, respectively, were as follows (in thousands):
		March 31,			December 31,
		2015			2014
	Series A convertible preferred units	7,052			5,745
	Series B convertible units	1,278			1,255
	Limited Partner common units	22,754			22,670
	General Partner units	392			392
	Distributions
	We made cash distributions as follows (in thousands):
		Three months ended March 31,
		2015				2014
	Series A convertible preferred units	—				1,320
	Limited Partner common units	10,713				4,897
	General Partner units	158				72
	General Partners' incentive distribution rights	1,288				410
		$	12,159			$	6,699
	The Partnership executed an amendment to its partnership agreement (the "Amendment"), which became effective March 30, 2015, related to its outstanding Series A Units. As a result of the Amendment, distributions on Series A Units will be made with paid-in-kind Series A Units, cash or a combination thereof, at the discretion of the board of directors of our General Partner, which began with the distribution for the three months ended June 30, 2014 and will continue through the distribution for the earlier of (a) the quarter ended March 31, 2016 or (b) the time in which the Series A-1 Units are converted into common units. At March 31, 2015, we have accrued $3.4 million for the paid-in-kind Series A Units. The distributions will be made in the second quarter of 2015.
	Net Income (Loss) attributable to Limited Partner Units
	Net income (loss) is allocated to the General Partner and the limited partners in accordance with their respective ownership percentages, after giving effect to contractual distributions on Series A Units, declared distributions on the Series B Units, common units representing Limited Partner interests and to the General Partner units, including incentive distribution rights. Unvested unit-based payment awards that contain non-forfeitable rights to distributions (whether paid or unpaid) are classified as participating securities and are included in our computation of basic and diluted net income per limited partner unit. Basic and diluted net income (loss) per limited partner unit is calculated by dividing limited partners’ interest in net income (loss) by the weighted average number of outstanding limited partner units during the period. We determined basic and diluted net income (loss) per limited partner unit as follows, (in thousands, except per unit amounts):
		Three months ended March 31,
		2015				2014
	Net income (loss) from continuing operations	$	835			$	558
	Less: Net income (loss) attributable to noncontrolling interests	14				108
	Net income (loss) from continuing operations attributable to the Partnership	821				450
	Less:
	Contractual distributions on Series A Units	3,411				3,182
	Declared distributions on Series B Units	420				—
	General partner's distribution	1,447				482
	General partner's share in undistributed loss	(189		)		(106		)
	Net income (loss) from continuing operations available to limited partners	(4,268		)		(3,108		)
	Net income (loss) from operations of disposal groups, net of tax, available to limited partners	5				(50		)
	Net income (loss) available to limited partners	$	(4,263	)		$	(3,158	)
	Weighted average number of units used in computation of limited partners’ net (loss) income per unit (basic and diluted)	22,703				9,846
	Limited partners' net loss per common unit
	Basic and diluted:
	Loss from continuing operations	$	(0.19	)		$	(0.32	)
	Loss from discontinued operations	—				—
	Net loss	$	(0.19	)		$	(0.32	)

LongTerm_Incentive_Plan

Long-Term Incentive Plan	3 Months Ended
	Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Long-Term Incentive Plan	Long-Term Incentive Plan
	Our General Partner manages our operations and activities and employs personnel who provide support to our operations. The board of directors of our General Partner provides grants awards under its long-term incentive plan (“LTIP”) for its employees, consultants and directors who perform services for it or its affiliates. At March 31, 2015 and December 31, 2014, 396,081 and 688,976 units, respectively, were available for future grant under the LTIP.
	LTIP awards are subject to forfeiture until the vesting date. The LTIP is administered by the board of directors of our General Partner which, at its discretion, may elect to settle such vested phantom units with a number of units equivalent to the fair market value at the date of vesting in lieu of cash. Although our General Partner has the option to settle in cash upon the vesting of phantom units, our General Partner has not historically settled these awards in cash. Although other types of awards are contemplated under the LTIP, all currently outstanding awards are phantom units without distribution equivalent rights.
	Generally, grants issued under the LTIP vest in increments of 25% on each grant date anniversary and do not contain any vesting other than continued employment requirements.
	The following table summarizes changes in our unit-based awards during the three months ended March 31, 2015 indicated, in units:
		Three months ended March 31, 2015
		Units		Weighted-Average Exercise Price
	Outstanding at beginning of period	201,132		$	19.85
	Granted	333,110		15.8
	Forfeited	(1,043	)	15.04
	Vested	(123,394	)	18.9
	Outstanding at end of period	409,805		$	16.86
	The fair value of our phantom units, which are subject to equity classification, is based on the fair value of our units at the grant date. Compensation costs related to these awards, including amortization, for the three months ended March 31, 2015 and 2014 were $1.7 million and $0.4 million, respectively, which are classified as Equity compensation expense in our condensed consolidated statements of operations and the non-cash portion in partners’ capital on our condensed consolidated balance sheets.
	The total fair value of vested units at the time of vesting was $2.3 million and $0.6 million for the three months ended March 31, 2015 and 2014, respectively.
	Equity compensation expense related to unvested awards not yet recognized at March 31, 2015 and 2014 was $6.6 million and $4.1 million, respectively, and the weighted average period over which this cost is expected to be recognized as of March 31, 2015 is approximately 3.4 years.

Income_Tax_Notes

Income Tax (Notes)	3 Months Ended
	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Income Tax	Income Taxes
	The Partnership is not a taxable entity for U.S. federal income tax purposes or for the majority of states that impose an income tax. Taxes on our income generally are borne by our unitholders through the allocation of taxable income. However, one of our subsidiaries, Blackwater Midstream Corp, is a taxable entity. Income tax expense for the three months ended March 31, 2015 was $0.2 million, resulting in an effective tax rate of 15.7%. For the three months ended March 31, 2014, income tax was a benefit of less than $0.1 million, resulting in an effective tax rate of 1.9%.
	The effective tax rates for the three months ended March 31, 2015 and March 31, 2014, differ from the statutory rate primarily due to the portion of the Partnership's income and loss that is not subject to U. S. federal income taxes, as well as transactions between the Partnership and its taxable subsidiary that generate tax deductions for the taxable subsidiary, which are eliminated in the consolidation of Net income (loss) before income tax (expense) benefit.

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies
	Legal proceedings
	We are not currently party to any pending litigation or governmental proceedings, other than ordinary routine litigation incidental to our business. While the ultimate impact of any proceedings cannot be predicted with certainly, our management believes that the resolution of any of our pending proceeds will not have a material adverse effect on our financial condition or results of operations.
	Environmental matters
	We are subject to federal and state laws and regulations relating to the protection of the environment. Environmental risk is inherent to natural gas pipeline, NGL and crude pipelines and operations, as well as terminal operations and we could, at times, be subject to environmental cleanup and enforcement actions. We attempt to manage this environmental risk through appropriate environmental policies and practices to minimize any impact our operations may have on the environment.
	Regulatory matters
	On December 11, 2014, American Midstream (Midla), LLC ("Midla"), a subsidiary of the Partnership, filed a Stipulation and Agreement (the "Agreement") which resolved all of the outstanding issues between Midla and its customers regarding its interstate pipeline that traverses Louisiana and Mississippi owned and operated by Midla. The parties involved reached agreement in order to provide continued service to Midla’s customers while addressing safety concerns with the existing pipeline.
	Midla and the parties agreed that Midla may retire the existing 1920s vintage pipeline and replace the existing natural gas service with a new pipeline from Winnsboro, Louisiana to Natchez, Mississippi (the “Midla-Natchez Line”) to serve existing residential, commercial, and industrial customers. Under the Agreement, customers not served by the new Midla-Natchez Line will be connected to other interstate or intrastate pipelines, other gas distribution systems, or offered conversion to propane service. The Agreement was approved by the FERC without modification on April 16, 2015, however, it is subject to final agreements and ongoing proceedings with the FERC. Under the Agreement Midla will execute long-term agreements to recover its investment in the Midla-Natchez Line.

RelatedParty_Transactions

Related-Party Transactions	3 Months Ended
	Mar. 31, 2015
Related Party Transactions [Abstract]
Related-Party Transactions	Related-Party Transactions
	Employees of our General Partner are assigned to work for us. Where directly attributable, the costs of all compensation, benefits expenses and employer expenses for these employees are charged directly by our General Partner to the Partnership, which, in turn, charges the appropriate subsidiary. Our General Partner does not record any profit or margin for the administrative and operational services charged to us. During the three months ended March 31, 2015, administrative and operational services expenses of $7.7 million were charged to us by our General Partner. During the three months ended March 31, 2014, administrative and operational services expenses of $5.0 million were charged to us by our General Partner. For the three months ended March 31, 2014, our General Partner incurred approximately $0.5 million of costs primarily associated with certain business development activities.
	During the first quarter of 2015, the Partnership and an affiliate of HPIP entered into an arrangement under which the affiliate reimbursed the Partnership for right-of-ways purchased on the affiliates' behalf for approximately $2.8 million.
	During the second quarter of 2014, the Partnership and an affiliate of its General Partner entered into a Management Service Fee arrangements under which the affiliate pays a monthly fee to reimburse the Partnership for administrative expenses incurred on the affiliates' behalf. During the three months ended March 31, 2015, the Partnership recognized $0.4 million in management fee income that has been recorded as a reduction to Selling, general and administrative expenses.

Reporting_Segments

Reporting Segments	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Reporting Segments	Reporting Segments
	Our operations are located in the United States and are organized into three reporting segments: i) Gathering and Processing, ii) Transmission and iii) Terminals.
	Gathering and Processing
	Our Gathering and Processing segment provides “wellhead-to-market” services to producers of natural gas and oil, which include transporting raw natural gas from the wellhead through gathering systems, treating the raw natural gas, processing raw natural gas to separate the NGLs from the natural gas, fractionating NGLs, and selling or delivering pipeline-quality natural gas and NGLs to various markets and pipeline systems.
	Transmission
	Our Transmission segment transports and delivers natural gas from producing wells, receipt points or pipeline interconnects for shippers and other customers, which include local distribution companies, utilities and industrial, commercial and power generation customers.
	Terminals
	Our Terminals segment provides above-ground storage services at our marine terminals that support various commercial customers, including commodity brokers, refiners and chemical manufacturers to store a range of products, including petroleum products, distillates, chemicals and agricultural products.
	These segments are monitored separately by management for performance and are consistent with the Partnership's internal financial reporting. These segments have been identified based on the differing products and services, regulatory environment and the expertise required for these operations. Gross margin is the performance measure utilized by management to monitor the business of each segment.
	The following tables set forth our segment information for the three months ended March 31, 2015 and 2014 (in thousands):
		Three months ended March 31, 2015
		Gathering			Transmission		Terminals		Total
		and
		Processing
	Revenue	$	48,449		$	11,748	$	4,265	$	64,462
	Gain (loss) on commodity derivatives, net	147			—		—		147
	Total revenue	48,596			11,748		4,265		64,609
	Operating expenses:
	Purchases of natural gas, NGL's and condensate	27,319			1,659		—		28,978
	Direct operating expenses	9,092			3,180		1,595		13,867
	Selling, general and administrative expenses								6,935
	Equity compensation expense								1,698
	Depreciation, amortization and accretion expense								9,689
	Total operating expenses								61,167
	Gain (loss) on sale of assets, net								(8		)
	Interest expense								(2,610		)
	Earnings in unconsolidated affiliates								167
	Income tax benefit (expense)								(156		)
	Gain (loss) from discontinued operations, net of tax								5
	Net income (loss)								840
	Less: Net income (loss) attributable to noncontrolling interests								14
	Net income (loss) attributable to the Partnership								$	826
	Segment gross margin (a)	$	21,045		$	10,061	$	2,670	$	33,776
		Three months ended March 31, 2014
		Gathering			Transmission		Terminals		Total
		and
		Processing
	Revenue	$	51,625		$	25,129	$	3,614	$	80,368
	Gain (loss) on commodity derivatives, net	(130		)	—		—		(130		)
	Total revenue	51,495			25,129		3,614		80,238
	Operating expenses:
	Purchases of natural gas, NGL's and condensate	41,121			14,100		—		55,221
	Direct operating expenses	4,168			3,118		1,675		8,961
	Selling, general and administrative expenses								5,593
	Equity compensation expense								360
	Depreciation, amortization and accretion expense								7,632
	Total operating expenses								77,767
	Gain (loss) on sale of assets, net								(21		)
	Interest expense								(1,903		)
	Income tax benefit (expense)								11
	Gain (loss) from discontinued operations, net of tax								(50		)
	Net income (loss)								508
	Less: Net income (loss) attributable to noncontrolling interests								108
	Net income (loss) attributable to the Partnership								$	400
	Segment gross margin (a)	$	10,128		$	11,014	$	1,939	$	23,081
		March 31,			December 31,
		2015			2014
	Segment assets:
	Gathering and Processing	$	686,158		$	686,395
	Transmission	132,661			132,767
	Terminals	78,752			71,180
	Other (b)	35,074			26,302
	Total assets	$	932,645		$	916,644
	(a)	Segment gross margin for our Gathering and Processing segment consists of revenue and realized gains or (losses) on commodity derivatives less purchases of natural gas, NGLs and condensate and revenue from construction, operating and maintenance agreements (“COMA”). Segment gross margin for our Transmission segment consists of revenue, less purchases of natural gas and COMA. Segment gross margin for our Terminals segment consists of revenue, less direct operating expenses. Gross margin consists of the sum of the segment gross margin amounts for each of these segments. As an indicator of our operating performance, gross margin should not be considered an alternative to, or more meaningful than, net income or cash flow from operations as determined in accordance with GAAP. Our gross margin may not be comparable to a similarly titled measure of another company because other entities may not calculate gross margin in the same manner.
(b)	Other assets not allocable to segments consist of investment in unconsolidated affiliates, corporate leasehold improvements, and other assets.

Subsequent_Events

Subsequent Events	3 Months Ended
	Mar. 31, 2015
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events
	GP Contribution
	In connection with the issuance of the Series A-2 Units discussed in Note 13, we received proceeds of $0.3 million from our General Partner as consideration for 18,706 additional notional general partner units in April of 2015.
	Distribution
	On April 23, 2015, we announced a distribution of $0.4725 per unit for the quarter ended March 31, 2015, or $1.89 per unit on an annualized basis, payable on May 15, 2015 to unitholders of record on May 7, 2015.

Organization_and_Basis_of_Pres1

Organization and Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business	Nature of Business
	We are engaged in the business of gathering, treating, processing, and transporting natural gas, fractionating NGLs and storing specialty chemical products through our ownership and operation of twelve gathering systems, five processing facilities, three fractionation facilities, four marine terminal sites, three interstate pipelines and five intrastate pipelines. We also own a 66.7% non-operating interest in Main Pass Oil Gathering, LP ("MPOG"), a crude oil gathering and processing system, a 46.0% non-operated interest in Mesquite, an off-spec condensate fractionation project, as well as a 50% undivided, non-operating interest in the Burns Point Plant, a natural gas processing plant. Our primary assets, which are strategically located in Alabama, Georgia, Louisiana, Maryland, Mississippi, North Dakota, Tennessee and Texas, provide critical infrastructure that links producer of natural gas, NGLs, condensate and specialty chemicals to numerous intermediate and end-use markets. We currently operate more than 3,000 miles of pipelines that gather and transport over 1 Bcf/d of natural gas and operate approximately 1.7 million barrels of storage capacity across four marine terminal sites.
Basis of Presentation	Basis of Presentation
	These unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles ("GAAP") for interim financial information. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. The year-end balance sheet data was derived from consolidated audited financial statements but does not include disclosures required by GAAP for annual periods. We have made reclassifications to amounts reported in prior period condensed consolidated financial statements to conform to our current year presentation. These reclassifications did not have an impact on net income (loss) for the period previously reported. The information furnished herein reflects all normal recurring adjustments that are, in the opinion of management, necessary for a fair statement of financial position and results of operations for the respective interim periods.
	The financial results for the three months ended March 31, 2014, have been reclassified to present an asset group previously presented as held for sale as held and used.
	Our financial results for the three months ended March 31, 2015 are not necessarily indicative of the results that may be expected for the full year ended December 31, 2015. These unaudited condensed consolidated financial statements should be read in conjunction with our consolidated financial statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2014 (“Annual Report”) filed with the Securities and Exchange Commission on March 10, 2015.
Consolidation Policy	Consolidation Policy
	The accompanying condensed consolidated financial statements include accounts of American Midstream Partners, LP, and its controlled subsidiaries. All significant inter-company accounts and transactions have been eliminated in the preparation of the accompanying condensed consolidated financial statements. We hold a 50% undivided interest in the Burns Point gas processing facility in which we are responsible for our proportionate share of the costs and expenses of the facility. Our condensed consolidated financial statements reflect our proportionate share of the revenues, expenses, assets and liabilities of this undivided interest. As of March 31, 2015, we also hold a 92.2% undivided interest in the Chatom Processing and Fractionation facility (the "Chatom System"). Our condensed consolidated financial statements reflect the accounts of the Chatom System and the interests in the Chatom System held by non-affiliated working interest owners are reflected as noncontrolling interests in the Partnership's condensed consolidated financial statements.
Use of Estimates	Use of Estimates
	When preparing condensed consolidated financial statements in conformity with GAAP, management must make estimates and assumptions based on information available at the time. These estimates and assumptions affect the reported amounts of assets, liabilities, revenues and expenses, as well as the disclosures of contingent assets and liabilities as of the date of the financial statements. Estimates and assumptions are based on information available at the time such estimates and assumptions are made. Adjustments made with respect to the use of these estimates and assumptions often relate to information not previously available. Uncertainties with respect to such estimates and assumptions are inherent in the preparation of financial statements. Estimates and assumptions are used in, among other things i) estimating unbilled revenues, product purchases and operating and general and administrative costs, ii) developing fair value estimates, including assumptions for future cash flows and discount rates, iii) analyzing long-lived assets, goodwill and intangible assets for possible impairment, iv) estimating the useful lives of assets and v) determining amounts to accrue for contingencies, guarantees and indemnifications. Actual results, therefore, could differ materially from estimated amounts.

Acquisitions_and_Divestitures_

Acquisitions and Divestitures (Tables)	3 Months Ended
	Mar. 31, 2015
Business Acquisition [Line Items]
Schedule of Business Acquisitions, by Acquisition [Table Text Block]	The following table summarizes the fair value of consideration transferred to acquire Costar and the allocation of that amount to the assets acquired, liabilities assumed and the noncontrolling interest based upon their respective fair values as of the acquisition date (in thousands).
	Fair value of consideration transferred:
	Cash	$	265,201
	Limited partner common units	147,296
	Total fair value of consideration	$	412,497
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]
	Fair Value of assets acquired, liabilities assumed and noncontrolling interest:
	Working capital	$	8,152
	Property, plant and equipment:
	Processing plants	$	48,357
	Pipelines	128,799
	Land	1,244
	Buildings	682
	Equipment	9,827
	Construction in progress	16,146
	Total property, plant and equipment	205,055
	Investment in unconsolidated affiliate	11,884
	Intangible assets:
	Customer relationships	53,400
	Dedicated acreage	32,000
	Goodwill	102,225
	Noncontrolling interest	(219		)
		$	412,497
	The following table summarizes the final allocation of the purchase price to the assets acquired based upon their respective fair values as of the acquisition date (in thousands):
	Property, plant and equipment:
	Land	$	2
	Pipelines	58,737
	Equipment	753
	Total property, plant and equipment	59,492
	Intangible assets	21,350
	Goodwill	23,567
	Total cash consideration	$	104,409

Discontinued_Operations_Operat

Discontinued Operations Operation of discontinued operations (Tables)	3 Months Ended
	Mar. 31, 2015
Discontinued Operations and Disposal Groups [Abstract]
Schedule of Disposal Groups, Including Discontinued Operations, Income Statement, Balance Sheet and Additional Disclosures [Table Text Block]	The following table presents the revenue, expense and gain (loss) from operations of disposal groups associated with the assets classified as held for sale for the three months ended March 31, 2015 and 2014 (in thousands, except per unit amounts):
		Three months ended March 31,
		2015			2014
	Revenue	$	64		$	237
	Expense	(55		)	(277		)
	Loss on sale of assets	—			(22		)
	Income tax benefit	(4		)	12
	Income (loss) from operations of disposal groups, net of tax	$	5		$	(50	)
	Limited partners' net income (loss) per unit from discontinued operations (basic and diluted)	$	—		$	—

Concentration_of_Credit_Risk_a1

Concentration of Credit Risk and Trade Accounts Receivable (Tables)	3 Months Ended
	Mar. 31, 2015
Risks and Uncertainties [Abstract]
Percentage of revenue earned from major customers	The following table summarizes the percentage of revenue earned from those customers that accounted for 10% or more of the Partnership's consolidated revenue in its condensed consolidated statement of operations for each of the periods presented below:
		Three months ended March 31,
		2015		2014
	Customer A	10	%	12	%
	Customer B	—	%	30	%
	Customer C	—	%	15	%
	Other	90	%	43	%
	Total	100	%	100	%

Other_Current_Assets_Tables

Other Current Assets (Tables)	3 Months Ended
	Mar. 31, 2015
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Other Current Assets	Other current assets consist of the following (in thousands):
		March 31,		December 31,
		2015		2014
	Prepaid insurance	$	2,845	$	4,162
	Restricted cash	25		6,475
	Other current assets	5,311		4,917
		$	8,181	$	15,554
	Restricted cash of $6.5 million as of December 31, 2014 consisted of a cash-backed letter of credit related to Costar operations that the Partnership was contractually obligated to maintain after the Costar Acquisition. The Partnership was released of this obligation in January 2015. Other current assets primarily consist of natural gas imbalances and amounts due from related parties.

Derivatives_Tables

Derivatives (Tables)	3 Months Ended
	Mar. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair value associated with commodity derivative instruments	As of March 31, 2015 and December 31, 2014, the value associated with our commodity derivatives, interest rate swap, and weather derivative were recorded in our condensed consolidated balance sheets, under the captions as follows (in thousands):
			Gross Risk Management Assets					Gross Risk Management Liabilities						Net Risk Management Assets (Liabilities)
	Balance Sheet Classification		March 31,			December 31, 2014		March 31,			December 31, 2014			March 31,			December 31, 2014
			2015					2015						2015
	Current		$	455		$	688	$	—		$	—		$	455		$	688
	Noncurrent		—			—		—			—			—			—
	Total assets		$	455		$	688	$	—		$	—		$	455		$	688
	Current		$	—		$	—	$	(168	)	$	(215	)	$	(168	)	$	(215	)
	Noncurrent		—			—		—			—			—			—
	Total liabilities		$	—		$	—	$	(168	)	$	(215	)	$	(168	)	$	(215	)
Realized and unrealized gains (losses) with commodity and interst rate derivative instruments	For the three months ended March 31, 2015 and 2014, respectively, the realized and unrealized gains (losses) associated with our commodity derivatives, interest rate swap instrument and weather derivative were recorded in our condensed consolidated statements of operations, under the captions as follows (in thousands):
		Three months ended March 31,
		Gain (loss) on derivatives
	Statement of Operations Classification	Realized			Unrealized
	2015
	Gain (loss) on commodity derivatives, net	$	139		$	8
	Interest expense	(102		)	47
	Direct operating expenses	(241		)	—
	Total	$	(204	)	$	55
	2014
	Gain (loss) on commodity derivatives, net	$	(102	)	$	(28	)
	Interest expense	(104		)	(11		)
	Direct operating expenses	(284		)	—
	Total	$	(490	)	$	(39	)

Fair_Value_Measurement_Tables

Fair Value Measurement (Tables)	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Fair value of financial instruments	Fair Value of Financial Instruments
	The following table sets forth by level within the fair value hierarchy, our commodity derivative instruments and interest rate swap, included as part of Risk management assets and Risk management liabilities within our condensed consolidated balance sheets, that were measured at fair value on a recurring basis as of March 31, 2015 and December 31, 2014 (in thousands):
		Carrying			Estimated Fair Value of the Asset (Liability)
		Amount			Level 1		Level 2			Level 3		Total
	Commodity derivative instruments, net
	March 31, 2015	$	294		$	—	$	294		$	—	$	294
	December 31, 2014	286			—		286			—		286
	Interest rate swap
	31-Mar-15	$	(168	)	$	—	$	(168	)	$	—	$	(168	)
	31-Dec-14	(215		)	—		(215		)	—		(215		)

Property_Plant_and_Equipment_T

Property, Plant and Equipment (Tables)	3 Months Ended
	Mar. 31, 2015
Property, Plant and Equipment [Abstract]
Property, plant and equipment, net	Property, plant and equipment, net, as of March 31, 2015 and December 31, 2014 were as follows (in thousands):
		Useful Life	March 31,			December 31,
		(in years)	2015			2014
	Land	N/A	$	5,282		$	5,282
	Construction in progress	N/A	101,263			77,550
	Base gas	N/A	1,108			1,108
	Buildings and improvements	4 to 40	7,252			6,855
	Processing and treating plants	8 to 40	80,838			80,837
	Pipelines	3 to 40	458,732			451,341
	Compressors	4 to 20	25,403			24,548
	Dock	20 to 40	8,072			8,072
	Tanks, truck rack and piping	20 to 40	30,155			30,079
	Equipment	8 to 20	8,860			8,855
	Computer software	5	3,490			3,490
	Total property, plant and equipment		730,455			698,017
	Accumulated depreciation		(123,704		)	(115,835		)
	Property, plant and equipment, net		$	606,751		$	582,182

Goodwill_and_Intangible_Assets1

Goodwill and Intangible Assets, Net (Tables)	3 Months Ended
	Mar. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Finite-Lived Intangible Assets	Intangible assets, net, consist of the following (in thousands):
		March 31,			December 31,
		2015			2014
	Gross carrying amount:
	Customer contracts	$	12,101		$	12,101
	Customer relationships	53,400			53,400
	Dedicated acreage	53,350			53,350
		$	118,851		$	118,851
	Accumulated amortization:
	Customer contracts	$	(11,636	)	$	(11,110	)
	Customer relationships	(1,197		)	(553		)
	Dedicated acreage	(1,326		)	(882		)
		$	(14,159	)	$	(12,545	)
	Net carrying amount:
	Customer contracts	$	465		$	991
	Customer relationships	52,203			52,847
	Dedicated acreage	52,024			52,468
		$	104,692		$	106,306

Accrued_Expenses_and_Other_Cur1

Accrued Expenses and Other Current Liabilities (Tables)	3 Months Ended
	Mar. 31, 2015
Other Liabilities Disclosure [Abstract]
Schedule of Accrued Liabilities	Accrued expenses and other current liabilities were as follows (in thousands):
		March 31,		December 31,
		2015		2014
	Accrued capital expenditures	$	15,403	$	17,134
	Accrued expenses	1,249		7,036
	Gas imbalances payable	967		1,069
	Other	3,665		561
		$	21,284	$	25,800

Debt_Obligations_Tables

Debt Obligations (Tables)	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Outstanding borrowings under the credit facility	Our outstanding borrowings under the credit facility were (in thousands):
		March 31,		December 31,
		2015		2014
	Revolving credit facility	$	386,850	$	372,950
	Other debt	1,833		2,908
	Total debt	388,683		375,858
	Less: current portion	1,833		2,908
	Long-term debt	$	386,850	$	372,950

Partners_Capital_Tables

Partners' Capital (Tables)	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
Numbers of units outstanding	Distributions
	We made cash distributions as follows (in thousands):
		Three months ended March 31,
		2015				2014
	Series A convertible preferred units	—				1,320
	Limited Partner common units	10,713				4,897
	General Partner units	158				72
	General Partners' incentive distribution rights	1,288				410
		$	12,159			$	6,699
	The number of units outstanding as of March 31, 2015 and December 31, 2014, respectively, were as follows (in thousands):
		March 31,			December 31,
		2015			2014
	Series A convertible preferred units	7,052			5,745
	Series B convertible units	1,278			1,255
	Limited Partner common units	22,754			22,670
	General Partner units	392			392
Schedule of Calulation for Net Income (Loss) Per Limited Partner Unit	We determined basic and diluted net income (loss) per limited partner unit as follows, (in thousands, except per unit amounts):
		Three months ended March 31,
		2015				2014
	Net income (loss) from continuing operations	$	835			$	558
	Less: Net income (loss) attributable to noncontrolling interests	14				108
	Net income (loss) from continuing operations attributable to the Partnership	821				450
	Less:
	Contractual distributions on Series A Units	3,411				3,182
	Declared distributions on Series B Units	420				—
	General partner's distribution	1,447				482
	General partner's share in undistributed loss	(189		)		(106		)
	Net income (loss) from continuing operations available to limited partners	(4,268		)		(3,108		)
	Net income (loss) from operations of disposal groups, net of tax, available to limited partners	5				(50		)
	Net income (loss) available to limited partners	$	(4,263	)		$	(3,158	)
	Weighted average number of units used in computation of limited partners’ net (loss) income per unit (basic and diluted)	22,703				9,846
	Limited partners' net loss per common unit
	Basic and diluted:
	Loss from continuing operations	$	(0.19	)		$	(0.32	)
	Loss from discontinued operations	—				—
	Net loss	$	(0.19	)		$	(0.32	)

LongTerm_Incentive_Plan_Tables

Long-Term Incentive Plan (Tables)	3 Months Ended
	Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Table summarizes our unit-based awards	The following table summarizes changes in our unit-based awards during the three months ended March 31, 2015 indicated, in units:
		Three months ended March 31, 2015
		Units		Weighted-Average Exercise Price
	Outstanding at beginning of period	201,132		$	19.85
	Granted	333,110		15.8
	Forfeited	(1,043	)	15.04
	Vested	(123,394	)	18.9
	Outstanding at end of period	409,805		$	16.86

Reporting_Segments_Tables

Reporting Segments (Tables)	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Segment information	The following tables set forth our segment information for the three months ended March 31, 2015 and 2014 (in thousands):
		Three months ended March 31, 2015
		Gathering			Transmission		Terminals		Total
		and
		Processing
	Revenue	$	48,449		$	11,748	$	4,265	$	64,462
	Gain (loss) on commodity derivatives, net	147			—		—		147
	Total revenue	48,596			11,748		4,265		64,609
	Operating expenses:
	Purchases of natural gas, NGL's and condensate	27,319			1,659		—		28,978
	Direct operating expenses	9,092			3,180		1,595		13,867
	Selling, general and administrative expenses								6,935
	Equity compensation expense								1,698
	Depreciation, amortization and accretion expense								9,689
	Total operating expenses								61,167
	Gain (loss) on sale of assets, net								(8		)
	Interest expense								(2,610		)
	Earnings in unconsolidated affiliates								167
	Income tax benefit (expense)								(156		)
	Gain (loss) from discontinued operations, net of tax								5
	Net income (loss)								840
	Less: Net income (loss) attributable to noncontrolling interests								14
	Net income (loss) attributable to the Partnership								$	826
	Segment gross margin (a)	$	21,045		$	10,061	$	2,670	$	33,776
		Three months ended March 31, 2014
		Gathering			Transmission		Terminals		Total
		and
		Processing
	Revenue	$	51,625		$	25,129	$	3,614	$	80,368
	Gain (loss) on commodity derivatives, net	(130		)	—		—		(130		)
	Total revenue	51,495			25,129		3,614		80,238
	Operating expenses:
	Purchases of natural gas, NGL's and condensate	41,121			14,100		—		55,221
	Direct operating expenses	4,168			3,118		1,675		8,961
	Selling, general and administrative expenses								5,593
	Equity compensation expense								360
	Depreciation, amortization and accretion expense								7,632
	Total operating expenses								77,767
	Gain (loss) on sale of assets, net								(21		)
	Interest expense								(1,903		)
	Income tax benefit (expense)								11
	Gain (loss) from discontinued operations, net of tax								(50		)
	Net income (loss)								508
	Less: Net income (loss) attributable to noncontrolling interests								108
	Net income (loss) attributable to the Partnership								$	400
	Segment gross margin (a)	$	10,128		$	11,014	$	1,939	$	23,081
		March 31,			December 31,
		2015			2014
	Segment assets:
	Gathering and Processing	$	686,158		$	686,395
	Transmission	132,661			132,767
	Terminals	78,752			71,180
	Other (b)	35,074			26,302
	Total assets	$	932,645		$	916,644
	(a)	Segment gross margin for our Gathering and Processing segment consists of revenue and realized gains or (losses) on commodity derivatives less purchases of natural gas, NGLs and condensate and revenue from construction, operating and maintenance agreements (“COMA”). Segment gross margin for our Transmission segment consists of revenue, less purchases of natural gas and COMA. Segment gross margin for our Terminals segment consists of revenue, less direct operating expenses. Gross margin consists of the sum of the segment gross margin amounts for each of these segments. As an indicator of our operating performance, gross margin should not be considered an alternative to, or more meaningful than, net income or cash flow from operations as determined in accordance with GAAP. Our gross margin may not be comparable to a similarly titled measure of another company because other entities may not calculate gross margin in the same manner.
	(b)	Other assets not allocable to segments consist of investment in unconsolidated affiliates, corporate leasehold improvements, and other assets.

Organization_and_Basis_of_Pres2

Organization and Basis of Presentation (Details)	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014
	billion_cubic_feet_per_day
	mi
	bbl
	facility
	pipeline
	gathering_system
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
General Partners' Capital Account, Percentage	95.00%
Limited Partners' Capital Account, Percentage	5.00%
Number of Gathering Systems	12
Number of Processing Facilities	5
Number of Fractionation Facilities	3
Number of Marine Terminal Sites	4
Number of Interstate Pipelines	3
Number of Intrastate Pipelines	5
Length of pipeline	3,000
Volume of Natural Gas, Operating	1
Million barrels of storage capacity	1,700,000
Noncontrolling Interest, Ownership Percentage by Parent	92.20%
Burns Point Plant [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of voting interests acquired	50.00%
Equity Method Investments [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Equity Method Investment, Ownership Percentage		66.70%	66.70%
Mesquite [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Equity Method Investment, Ownership Percentage	46.00%
MPOG [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Equity Method Investment, Ownership Percentage	66.70%

Summary_of_Significant_Account1

Summary of Significant Accounting Policies Recent Accounting Pronouncements (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015
Accounting Policies [Abstract]
Debt Issuance Cost	$10.50

Acquisitions_and_Divestitures_1

Acquisitions and Divestitures Lavaca Acquisition (Details) (USD $)	3 Months Ended		0 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Jan. 31, 2014	Dec. 31, 2014	Oct. 14, 2014
	mi		mi
Business Acquisition [Line Items]
Total revenue	$64,609	$80,238
Length of pipeline	3,000
Goodwill	142,053			142,236
Operating Income (Loss)	3,434	2,450
Lavaca [Member]
Business Acquisition [Line Items]
Total revenue	6,000
Business Acquisition, Purchase Price Allocation, Land				2
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment				59,492
Length of pipeline			120
Payments to Acquire Businesses, Gross			104,409
Fair Value Inputs, Discount Rate			10.50%
Business Acquisition, Purchase Price Allocation, Equipment				753
Business Acquisition, Purchase Price Allocation, Amortizable Intangible Assets				21,350
Goodwill					23,567
Operating Income (Loss)	2,200
Minimum [Member]
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life	0 years 5 months 0 days
Maximum [Member]
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life	30 years
Pipelines [Member] | Lavaca [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment				$58,737

Acquisitions_and_Divestitures_2

Acquisitions and Divestitures Blackwater Acquisition (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Business Combinations [Abstract]
Total revenue	$64,609	$80,238

Acquisitions_and_Divestitures_3

Acquisitions and Divestitures Madison Divestiture (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Significant Acquisitions and Disposals [Line Items]
Proceeds from disposals of property, plant and equipment	$2,800	$6,135
Madison [Member]
Significant Acquisitions and Disposals [Line Items]
Proceeds from disposals of property, plant and equipment		$6,100

Acquisitions_and_Divestitures_4

Acquisitions and Divestitures MPOG Acquisition (Details) (USD $)	3 Months Ended		1 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Aug. 14, 2014	Dec. 31, 2014	Sep. 30, 2014
Schedule of Equity Method Investments [Line Items]
Earnings in unconsolidated affiliates	$167,000	$0
Proceeds from Equity Method Investment, Dividends or Distributions, Return of Capital	1,000,000
Equity Method Investments [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage				66.70%	66.70%
Payments to Acquire Equity Method Investments			$12,000,000

Acquisitions_and_Divestitures_5

Acquisitions and Divestitures Costar Midstream (Details) (USD $)	3 Months Ended		0 Months Ended
Share data in Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Oct. 14, 2014	Dec. 31, 2014
Business Acquisition [Line Items]
Goodwill	$142,053,000			$142,236,000
Acquisition Working Capital Adjustment	200,000
Revenues	64,609,000	80,238,000
Operating Income (Loss)	3,434,000	2,450,000
Costar Midstream, L.L.C. [Member]
Business Acquisition [Line Items]
Percentage of voting interests acquired			100.00%
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Working Capital			8,152,000
Payments to Acquire Businesses, Gross			265,201,000
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable, Units			6.9
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable			147,296,000
Business Combination, Consideration Transferred			412,497,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Processing Plants			48,357,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Pipelines			128,799,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Land			1,244,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Buildings			682,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Equipment			9,827,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Construction in Progress			16,146,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment			205,055,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Investment in Unconsolidated Affiliate			11,884,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Customer Relationships			53,400,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Dedicated Acreage			32,000,000
Goodwill			102,225,000
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value			219,000
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest			412,497,000
Business Combination, Acquired Receivables, Gross Contractual Amount			11,200,000
Revenues	21,400,000
Operating Income (Loss)	$1,200,000
Minimum [Member] | Costar Midstream, L.L.C. [Member]
Business Acquisition [Line Items]
Fair Value Inputs, Discount Rate			11.00%
Maximum [Member] | Costar Midstream, L.L.C. [Member]
Business Acquisition [Line Items]
Fair Value Inputs, Discount Rate			16.00%

Acquisitions_and_Divestitures_6

Acquisitions and Divestitures Williams Acquisition (Details) (Williams [Member], USD $)	Mar. 31, 2014
In Millions, unless otherwise specified
Williams [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	$6.50

Discontinued_Operations_Detail

Discontinued Operations (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Revenue	$64,000	$237,000
Disposal Group, Including Discontinued Operation, Operating Expense	-55,000	-277,000
Discontinued Operation, Tax Effect of Discontinued Operation	-4,000	12,000
Income (loss) from discontinued operations, net of tax	5,000	-50,000
Income (loss) from discontinued operations	$0	$0
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	0	-22,000
Blackwater [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Other Assets, Current	100,000
Noncurrent assets held for sale, net	1,200,000
Current liabilities held for sale	$100,000

Concentration_of_Credit_Risk_a2

Concentration of Credit Risk and Trade Accounts Receivable (Details)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Concentration Risk [Line Items]
Concentration Risk, Market Risk	0.1
Entity-Wide Revenue, Major Customer, Percentage	100.00%	100.00%
Customer A [Member]
Concentration Risk [Line Items]
Entity-Wide Revenue, Major Customer, Percentage	10.00%	12.00%
Customer B [Member]
Concentration Risk [Line Items]
Entity-Wide Revenue, Major Customer, Percentage	0.00%	30.00%
Cusotmer C [Member]
Concentration Risk [Line Items]
Entity-Wide Revenue, Major Customer, Percentage	0.00%	15.00%
Customer Other [Member]
Concentration Risk [Line Items]
Entity-Wide Revenue, Major Customer, Percentage	90.00%	43.00%

Other_Current_Assets_Details

Other Current Assets (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid insurance	$2,845	$4,162
Restricted cash	25	6,475
Other current assets	5,311	4,917
Other Assets, Current	$8,181	$15,554

Derivatives_Fair_Value_of_Comm

Derivatives (Fair Value of Commodity Derivatives) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Derivative [Line Items]
Gross Risk Management Assets	$455	$688
Gross Risk Management Liabilities	0	0
Net Risk Management Assets (Liabilities)	455	688
Gross Risk Management Assets	0	0
Gross Risk Management Liabilities	-168	-215
Net Risk Management Assets (Liabilities)	168	215
Risk Management Assets [Member] | Commodity derivatives [Member]
Derivative [Line Items]
Gross Risk Management Assets	455	688
Gross Risk Management Liabilities	0	0
Net Risk Management Assets (Liabilities)	455	688
Risk Management Assets - Long Term [Member] | Commodity derivatives [Member]
Derivative [Line Items]
Gross Risk Management Assets	0	0
Gross Risk Management Liabilities	0	0
Net Risk Management Assets (Liabilities)	0	0
Risk Management Liabilities [Member] | Commodity derivatives [Member]
Derivative [Line Items]
Gross Risk Management Assets	0	0
Gross Risk Management Liabilities	-168	-215
Net Risk Management Assets (Liabilities)	168	215
Risk Management Liabilities - Long Term [Member] | Commodity derivatives [Member]
Derivative [Line Items]
Gross Risk Management Assets	0	0
Gross Risk Management Liabilities	0	0
Net Risk Management Assets (Liabilities)	$0	$0

Derivatives_Realized_and_Unrea

Derivatives (Realized and Unrealized Gains (Losses)) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Derivatives, Fair Value [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$147	($130)
Commodity derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivative, Loss on Derivative	-204	-490
Gain on commodity derivatives, net	55	-39
Gain (Loss) on Derivative Instruments [Member] | Commodity derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivative, Gain (Loss) on Derivative, Net	-139	-102
Gain on commodity derivatives, net	8	-28
Interest Expense [Member]
Derivatives, Fair Value [Line Items]
Derivative, Loss on Derivative	-102	-104
Gain on commodity derivatives, net	47	-11
Other Income [Member]
Derivatives, Fair Value [Line Items]
Derivative, Loss on Derivative	-241	-284
Gain on commodity derivatives, net	$0	$0

Derivatives_Details_Textual

Derivatives (Details Textual) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Jun. 30, 2014
	gal
Derivative [Line Items]
Aggregate notional volume of our commodity derivative	2,700,000
Amortization of weather derivative premium	$241,000	$284,000
Interest Rate Swap [Member]
Derivative [Line Items]
Notional amount of interest rate swap	100,000,000
Weather Contract [Member]
Derivative [Line Items]
Potential proceeds from derivative contract			10,000,000
Fair value of derivative	0
Payment for weather derivative premium			-1,000,000
Derivative term of contract	1 year 0 months 0 days
Amortization of weather derivative premium	$200,000

Fair_Value_Measurement_Details

Fair Value Measurement (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Commodity derivative instruments, net	$294	$286
Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Commodity derivative instruments, net	-168	-215
Estimate of Fair Value Measurement [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Commodity derivative instruments, net	294	286
Estimate of Fair Value Measurement [Member] | Commodity Contract [Member] | Level 1 [Member]
Derivatives, Fair Value [Line Items]
Commodity derivative instruments, net	0	0
Estimate of Fair Value Measurement [Member] | Commodity Contract [Member] | Level 2 [Member]
Derivatives, Fair Value [Line Items]
Commodity derivative instruments, net	294	286
Estimate of Fair Value Measurement [Member] | Commodity Contract [Member] | Level 3 [Member]
Derivatives, Fair Value [Line Items]
Commodity derivative instruments, net	0	0
Estimate of Fair Value Measurement [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Commodity derivative instruments, net	-168	-215
Estimate of Fair Value Measurement [Member] | Interest Rate Swap [Member] | Level 1 [Member]
Derivatives, Fair Value [Line Items]
Commodity derivative instruments, net	0	0
Estimate of Fair Value Measurement [Member] | Interest Rate Swap [Member] | Level 2 [Member]
Derivatives, Fair Value [Line Items]
Commodity derivative instruments, net	-168	-215
Estimate of Fair Value Measurement [Member] | Interest Rate Swap [Member] | Level 3 [Member]
Derivatives, Fair Value [Line Items]
Commodity derivative instruments, net	$0	$0

Property_Plant_and_Equipment_D

Property, Plant and Equipment (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation	-123,704	($115,835)
Property, plant and equipment, net	606,751	582,182
Land [Member]
Property, Plant and Equipment, Net [Abstract]
Property plant and equipment gross	5,282	5,282
Construction in progress [Member]
Property, Plant and Equipment, Net [Abstract]
Property plant and equipment gross	101,263	77,550
Base gas [Member]
Property, Plant and Equipment, Net [Abstract]
Property plant and equipment gross	1,108	1,108
Buildings and improvements [Member]
Property, Plant and Equipment, Net [Abstract]
Property plant and equipment gross	7,252	6,855
Processing and treating plants [Member]
Property, Plant and Equipment, Net [Abstract]
Property plant and equipment gross	80,838	80,837
Pipelines [Member]
Property, Plant and Equipment, Net [Abstract]
Property plant and equipment gross	458,732	451,341
Compressors [Member]
Property, Plant and Equipment, Net [Abstract]
Property plant and equipment gross	25,403	24,548
Dock [Member]
Property, Plant and Equipment, Net [Abstract]
Property plant and equipment gross	8,072	8,072
Tanks, truck rack and piping [Member]
Property, Plant and Equipment, Net [Abstract]
Property plant and equipment gross	30,155	30,079
Equipment [Member]
Property, Plant and Equipment, Net [Abstract]
Property plant and equipment gross	8,860	8,855
Computer software [Member]
Property, Plant and Equipment, Net [Abstract]
Property plant and equipment gross	3,490	3,490
Property, Plant And Equipment [Member]
Property, Plant and Equipment, Net [Abstract]
Property plant and equipment gross	730,455	$698,017
Maximum [Member] | Buildings and improvements [Member]
Property, Plant and Equipment, Net [Abstract]
Property plant and equipment in useful life	40 years
Maximum [Member] | Processing and treating plants [Member]
Property, Plant and Equipment, Net [Abstract]
Property plant and equipment in useful life	40 years
Maximum [Member] | Pipelines [Member]
Property, Plant and Equipment, Net [Abstract]
Property plant and equipment in useful life	40 years
Maximum [Member] | Compressors [Member]
Property, Plant and Equipment, Net [Abstract]
Property plant and equipment in useful life	20 years
Maximum [Member] | Equipment [Member]
Property, Plant and Equipment, Net [Abstract]
Property plant and equipment in useful life	20 years
Maximum [Member] | Computer software [Member]
Property, Plant and Equipment, Net [Abstract]
Property plant and equipment in useful life	5 years
Minimum [Member] | Buildings and improvements [Member]
Property, Plant and Equipment, Net [Abstract]
Property plant and equipment in useful life	4 years
Minimum [Member] | Processing and treating plants [Member]
Property, Plant and Equipment, Net [Abstract]
Property plant and equipment in useful life	8 years
Minimum [Member] | Pipelines [Member]
Property, Plant and Equipment, Net [Abstract]
Property plant and equipment in useful life	3 years
Minimum [Member] | Compressors [Member]
Property, Plant and Equipment, Net [Abstract]
Property plant and equipment in useful life	4 years
Minimum [Member] | Equipment [Member]
Property, Plant and Equipment, Net [Abstract]
Property plant and equipment in useful life	8 years

Property_Plant_and_Equipment_D1

Property, Plant and Equipment (Details Textual) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Capitalized interest	$200,000	$100,000
Depreciation	7,900,000	6,500,000
AlaTenn system [Member]
Property, Plant and Equipment [Line Items]
Property plant and equipment gross	$102,800,000		$101,900,000

Goodwill_and_Intangible_Assets2

Goodwill and Intangible Assets, Net (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Segment Reporting Information [Line Items]
Goodwill	$142,053,000		$142,236,000
Acquisition Working Capital Adjustment	200,000
Amortization of Intangible Assets	1,600,000	700,000
Gathering And Processing [Member]
Segment Reporting Information [Line Items]
Goodwill	125,800,000		125,900,000
Terminals [Member]
Segment Reporting Information [Line Items]
Goodwill	$16,300,000		$16,300,000
Minimum [Member]
Segment Reporting Information [Line Items]
Finite-Lived Intangible Asset, Useful Life	0 years 5 months 0 days
Maximum [Member]
Segment Reporting Information [Line Items]
Finite-Lived Intangible Asset, Useful Life	30 years

Goodwill_and_Intangible_Assets3

Goodwill and Intangible Assets, Net Schedule of Intangible Assets (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount:	$118,851	$118,851
Accumulated amortization:	14,159	12,545
Net carrying amount:	104,692	106,306
Customer Contracts [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount:	12,101	12,101
Accumulated amortization:	11,636	11,110
Net carrying amount:	465	991
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount:	53,400	53,400
Accumulated amortization:	1,197	553
Net carrying amount:	52,203	52,847
Dedicated Acreage [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount:	53,350	53,350
Accumulated amortization:	1,326	882
Net carrying amount:	$52,024	$52,468

Accrued_Expenses_and_Other_Cur2

Accrued Expenses and Other Current Liabilities (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Other Liabilities Disclosure [Abstract]
Accrued capital expenditures	$15,403	$17,134
Accrued expenses	1,249	7,036
Gas imbalances payable	967	1,069
Other	3,665	561
Accrued expenses and other current liabilities	$21,284	$25,800

Debt_Obligations_Details

Debt Obligations (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Debt Disclosure [Abstract]
Line of Credit Facility, Amount Outstanding Limit	$500,000,000
Revolving credit facility	386,850,000	372,950,000
Other debt	1,833,000	2,908,000
Total debt	388,683,000	375,858,000
Less: current portion	1,833,000	2,908,000
Long-term debt	$386,850,000	$372,950,000

Debt_Obligations_Details_Textu

Debt Obligations (Details Textual) (USD $)	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Debt Instrument [Line Items]
Line of Credit Facility, Amount Outstanding Limit	$500,000,000
Long-Term Debt (Textual) [Abstract]
Letter of credit outstanding	5,100,000	1,600,000
Revolving credit facility	386,850,000	372,950,000
Ratio of Indebtedness to Net Capital	4.97
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.50%
Debt Instrument, Interest Coverage Ratio	11.06
Debt, Weighted Average Interest Rate	2.37%		4.40%
Proceeds from (Payments for) Other Financing Activities	3,300,000
Debt Instrument, Periodic Payment	$400,000
Maximum [Member]
Long-Term Debt (Textual) [Abstract]
Ratio of Indebtedness to Net Capital	4.75
Ratio of indebtedness to net capital, after permitted acquisition	5.25
Minimum [Member]
Long-Term Debt (Textual) [Abstract]
Debt Instrument, Interest Coverage Ratio	2.5
Federal Funds [Member]
Long-Term Debt (Textual) [Abstract]
Debt Instrument, Interest Rate, Stated Percentage	0.50%
Eurodollar [Member]
Long-Term Debt (Textual) [Abstract]
Debt Instrument, Interest Rate, Stated Percentage	1.00%
Insurance Premium Financing [Member]
Long-Term Debt (Textual) [Abstract]
Debt Instrument, Interest Rate, Stated Percentage	3.95%
Fiscal Quarter Ending December 31, 2014 [Member] | Debt Instrument, Fourth Amendment [Member] | Base Rate [Member] | Maximum [Member]
Long-Term Debt (Textual) [Abstract]
Debt Instrument, Basis Spread on Variable Rate	3.25%
Fiscal Quarter Ending December 31, 2014 [Member] | Debt Instrument, Fourth Amendment [Member] | Base Rate [Member] | Minimum [Member]
Long-Term Debt (Textual) [Abstract]
Debt Instrument, Basis Spread on Variable Rate	2.00%
Fiscal Quarter Ending December 31, 2014 [Member] | Debt Instrument, Fourth Amendment [Member] | Eurodollar [Member] | Maximum [Member]
Long-Term Debt (Textual) [Abstract]
Debt Instrument, Basis Spread on Variable Rate	2.25%
Fiscal Quarter Ending December 31, 2014 [Member] | Debt Instrument, Fourth Amendment [Member] | Eurodollar [Member] | Minimum [Member]
Long-Term Debt (Textual) [Abstract]
Debt Instrument, Basis Spread on Variable Rate	1.00%

Partners_Capital_Details

Partners' Capital (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Jun. 30, 2014	8-May-15	Dec. 31, 2014	Jan. 29, 2014
Limited Partners' Capital Account, Units Issued						3,400,000
Series A convertible preferred, units, outstanding	7,052,000			7,052,207	5,745,000
General partner interest units	392,000				392,000
Sale of Stock, Price Per Share						$26.75
Issuance of common units, net of offering costs			$86,900
Payments of Capital Distribution	12,159	6,699
AIM Midstream Holdings No. of units outstanding [Member]
Limited partners/ Series B, units outstanding					22,670,000
Limited partner subordinated units					392,000
Series B [Member]
Unitholder distributions	420	0
Limited partners/ Series B, units outstanding				1,277,772	1,255,000
Limited Partner Series B Convertible Units [Member]
Limited Partners' Capital Account, Units Issued	1,278,000				1,255,000
Limited partners/ Series B, units outstanding	1,278,000				1,255,000
Limited Partner Common Units [Member]
Limited Partners' Capital Account, Units Issued	22,754,000				22,670,000
Limited partners/ Series B, units outstanding	22,754,000				22,670,000
Limited Partner [Member]
Unitholder distributions	10,713	4,897
General Partner [Member]
Unitholder distributions	158	72
General Partner, Incentive Distribution Rights [Member]
Unitholder distributions	1,288	410
Series A [Member] | Preferred Partner [Member]
Unitholder distributions	$0	$1,320

Partners_Capital_Details_Textu

Partners Capital (Details Textual) (USD $)	0 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	0 Months Ended
	Feb. 21, 2014	Mar. 31, 2015	Jun. 30, 2014	Mar. 31, 2014	Mar. 30, 2015	Feb. 05, 2014	Jan. 29, 2014	Dec. 31, 2014
Subsidiary, Sale of Stock [Line Items]
Warrants Not Settleable in Cash, Fair Value Disclosure	$23.89
Partners Capital (Textual) [Abstract]
General partner interest		1.30%
Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest		98.70%
Limited Partners' Capital Account, Units Issued							3,400,000
Sale of Stock, Price Per Share							$26.75
Issuance of common units, net of offering costs			86,900,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	300,000					300,000
Stock and Warrants Issued During Period, Value, Preferred Stock and Warrants	7,200,000
Class of Warrant or Right, Exercise Price of Warrants or Rights						$0.01
Fair Value, Paid In Kind Distributions, Aggregate		3,400,000
Partnership Interest [Member]
Partners Capital (Textual) [Abstract]
Other Ownership Interests, Units Outstanding								392,000
Series B [Member]
Subsidiary, Sale of Stock [Line Items]
Unitholder distributions		0		0
Limited Partner [Member]
Subsidiary, Sale of Stock [Line Items]
Unitholder distributions		14,496,000		8,037,000
Partners Capital (Textual) [Abstract]
Issuance of common units, net of offering costs				86,926,000
Stock and Warrants Issued During Period, Value, Preferred Stock and Warrants				7,164,000
General Partner [Member]
Subsidiary, Sale of Stock [Line Items]
Unitholder distributions		1,495,000		524,000
Partners Capital (Textual) [Abstract]
Stock and Warrants Issued During Period, Value, Preferred Stock and Warrants				7,164,000
Series B [Member]
Subsidiary, Sale of Stock [Line Items]
Unitholder distributions		420,000		0
Issuance of Preferred Units [Member] | Series A [Member] | Magnolia Infrastructure Partners, LLC [Member]
Subsidiary, Sale of Stock [Line Items]
Partners' Capital Account, Private Placement of Units, Additional Authorized					25,000,000
Partners Capital (Textual) [Abstract]
Partners' Capital Account, Private Placement of Units					$20,000,000

Partners_Capital_Calculation_o

Partners' Capital (Calculation of Net Income (Loss) Per Limited Partner Unit) (Details) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Less: Comprehensive income (loss) attributable to noncontrolling interests	$14	$108
Net income (loss) from continuing operations attributable to the Partnership	821	450
Temporary Equity, Dividends, Adjustment		3,182
General Partners' Capital Account, Period Undistributed Income (Loss) From Continuing Operations, Amount	-189	-106
Net income (loss) from continuing operations available to limited partners	-4,268	-3,108
Net income (loss) from operations of disposal groups, net of tax, available to limited partners	5	-50
Net income (loss) available to limited partners	-4,263	-3,158
Weighted average number of units used in computation of limited partners’ net (loss) income per unit (basic and diluted)	22,703	9,846
Net income (loss) from continuing operations available to limited partners	($0.19)	($0.32)
Loss from discontinued operations	$0	$0
Net loss	($0.19)	($0.32)
Net income (loss) from continuing operations	835	558
Series A [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Accrued Paid in Kind			3,411
Series B [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
General partner's distribution	-420	0
General Partner [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
General partner's distribution	-1,495	-524
Dividend Declared [Member] | General Partner [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
General partner's distribution	($1,447)	($482)

LongTerm_Incentive_Plan_Detail

Long-Term Incentive Plan (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Unit-Based Award
Equity compensation expense	$1,698,000	$360,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	396,081		688,976
Grants Issued Under Long Term Incentive Plan	25.00%
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value	2,300,000	600,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	$6,600,000	$4,100,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price	$16.86		$19.85
Table Summarizes Unit Based Awards
Outstanding, Beginning period	201,132,000
Granted	333,110,000
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price	$15.80
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	-1,043,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price	$15.04
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	123,394,000
LTIP vesting, Shares	($18.90)
Outstanding, Ending period	409,805,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	3 years 5 months

Income_Tax_Details

Income Tax (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Income Tax Disclosure [Abstract]
Income tax (expense) benefit	($156)	$11
Effective Income Tax Rate, Continuing Operations	15.70%	-1.90%

Related_Party_Transactions_Det

Related- Party Transactions (Details Textual) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Related Party Transaction [Line Items]
Proceeds from Sale of Other Assets	$2.80
Management Fees Revenue	0.4
American Midstream, L.L.C [Member]
Related Party Transaction [Line Items]
General and Administrative Expense	7.7	5
Business Development		$0.50

Reporting_Segments_Details

Reporting Segments (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Segment Reporting, Revenue Reconciling Item [Line Items]
Segment assets:	$932,645,000		$916,644,000
Segment information
Revenue	64,462,000	80,368,000
Gain (loss) on commodity derivatives, net	147,000	-130,000
Total revenue	64,609,000	80,238,000
Purchases of natural gas, NGLs and condensate	28,978,000	55,221,000
Direct operating expenses	-13,867,000	-8,961,000
Selling, general and administrative expenses	6,935,000	5,593,000
Equity compensation expense	1,698,000	360,000
Depreciation, amortization and accretion expense	9,689,000	7,632,000
Total operating expenses	61,167,000	77,767,000
Gain (loss) on sale of assets, net	-8,000	-21,000
Income (loss) from discontinued operations, net of tax	5,000	-50,000
Interest expense	-2,610,000	-1,903,000
Earnings in unconsolidated affiliates	167,000	0
Income tax benefit (expense)	156,000	-11,000
Net income (loss)	840,000	508,000
Less: Comprehensive income (loss) attributable to noncontrolling interests	14,000	108,000
Net income (loss) attributable to the Partnership	826,000	400,000
Segment gross margin	33,776,000	23,081,000
Gathering And Processing [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Segment assets:	686,158,000		686,395,000
Transmission [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Segment assets:	132,661,000		132,767,000
Gathering and Processing reporting segment [Member]
Segment information
Revenue	48,449,000	51,625,000
Gain (loss) on commodity derivatives, net	147,000	-130,000
Total revenue	48,596,000	51,495,000
Purchases of natural gas, NGLs and condensate	27,319,000	41,121,000
Direct operating expenses	-9,092,000	-4,168,000
Segment gross margin	21,045,000	10,128,000
Transmission reporting segment [Member]
Segment information
Revenue	11,748,000	25,129,000
Gain (loss) on commodity derivatives, net	0	0
Total revenue	11,748,000	25,129,000
Purchases of natural gas, NGLs and condensate	1,659,000	14,100,000
Direct operating expenses	-3,180,000	-3,118,000
Segment gross margin	10,061,000	11,014,000
Terminals [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Segment assets:	78,752,000		71,180,000
Segment information
Total revenue	4,265,000	3,614,000
Terminals reporting segment [Member]
Segment information
Revenue	4,265,000	3,614,000
Gain (loss) on commodity derivatives, net	0	0
Purchases of natural gas, NGLs and condensate	0	0
Direct operating expenses	-1,595,000	-1,675,000
Segment gross margin	2,670,000	1,939,000
Other Segments [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Segment assets:	$35,074,000		$26,302,000

Reporting_Segments_Details_Tex

Reporting Segments (Details Textual)	3 Months Ended
	Mar. 31, 2015
	segment
Segment Reporting Information [Line Items]
Number of Operating Segments	3

Subsequent_Events_Details

Subsequent Events (Details) (USD $)	3 Months Ended		0 Months Ended	1 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Apr. 23, 2015	Apr. 30, 2105	Dec. 31, 2014	Apr. 30, 2015
Business Acquisition [Line Items]
General Partners' Capital Account, Units Issued	392,000				392,000
Distribution declared per common unit (a)	$0.47	$0.45
Subsequent Event [Member]
Business Acquisition [Line Items]
Unitholder contributions				$300
General Partners' Capital Account, Units Issued						18,706
Distribution declared per common unit (a)			$0.47
Distribution Made to Limited Partner, Distributions Declared, Per Unit, Annualized Basis			$1.89

Uncategorized_Items

Uncategorized Items	12/31/12
	USD ($)
[amid_Cashandcashequivalentsincludingdiscontinuedoperations]	393,000