Third Coast Midstream (AMID) 10-Q 9 Nov 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Nov. 06, 2018
Document Information [Line Items]
Entity Registrant Name	American Midstream Partners, LP
Entity Central Index Key	1,513,965
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Amendment Flag	false
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding (in shares)		53,005,627
Series A
Document Information [Line Items]
Entity Common Stock, Shares Outstanding (in shares)		11,009,729
Series C
Document Information [Line Items]
Entity Common Stock, Shares Outstanding (in shares)		9,241,642

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 22,758	$ 8,782
Restricted cash	25,744	20,352
Accounts receivable, net of allowance for doubtful accounts of $706 and $225 as of September 30, 2018 and December 31, 2017, respectively	84,819	98,132
Inventory	3,080	2,966
Other current assets	25,971	23,420
Assets held for sale	126,690	0
Total current assets	289,062	153,652
Property, plant and equipment, net	993,920	1,095,585
Goodwill	51,723	128,866
Restricted cash-long term	5,068	5,045
Intangible assets, net	136,537	174,010
Investments in unconsolidated affiliates	336,789	348,434
Other assets, net	21,506	17,874
Total assets	1,834,605	1,923,466
Current liabilities
Accounts payable	48,336	41,102
Accrued gas purchases	14,376	19,986
Accrued expenses and other current liabilities	116,141	68,854
Current portion of long-term debt	603,502	7,551
Liabilities held for sale	1,922	0
Total current liabilities	784,277	137,493
Asset retirement obligations	68,090	66,194
Other long-term liabilities	15,770	2,080
Long-term debt	501,219	1,201,456
Deferred tax liability	1,351	8,123
Total liabilities	1,370,707	1,415,346
Commitments and contingencies
Convertible preferred units	317,180	317,180
Equity and partners’ capital
General Partner interests (981 and 965 units issued and outstanding as of September 30, 2018 and December 31, 2017, respectively)	(66,254)	(96,552)
Limited Partner interests (52,990 and 52,711 units issued and outstanding as of September 30, 2018 and December 31, 2017, respectively)	199,173	273,703
Accumulated other comprehensive income	19	28
Total partners’ capital	132,938	177,179
Noncontrolling interests	13,780	13,761
Total equity and partners’ capital	146,718	190,940
Total liabilities, equity and partners’ capital	$ 1,834,605	$ 1,923,466

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Allowance for doubtful accounts receivable	$ 706	$ 225
General partner interests, units issued (in shares)	981	965
General partner interests, units outstanding (in shares)	981	965
Limited Partner interests, units issued (in shares)	52,990	52,711
Limited Partner interests, units outstanding (in shares)	52,990	52,711

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue:
Revenue	$ 202,580	$ 162,887	$ 628,920	$ 488,431
Loss on commodity derivatives, net	(234)	(597)	(530)	(33)
Total revenue	202,346	162,290	628,390	488,398
Operating expenses:
Costs of sales	150,274	112,398	461,948	342,886
Direct operating expenses	20,407	20,705	65,595	56,819
Corporate expenses	23,857	27,083	69,922	84,570
Termination fee	17,000	0	17,000	0
Depreciation, amortization and accretion	23,040	26,781	66,274	78,834
Gain on sale of assets, net	(99,396)	(4,061)	(99,491)	(4,064)
Total operating expenses	135,182	182,906	581,248	559,045
Operating income (loss)	67,164	(20,616)	47,142	(70,647)
Other income (expense), net
Interest expense, net of capitalized interest	(22,267)	(17,759)	(55,834)	(51,037)
Other income (expense), net	(128)	34,085	62	32,248
Earnings in unconsolidated affiliates	24,622	16,827	47,742	49,781
Income (loss) from continuing operations before income taxes	69,391	12,537	39,112	(39,655)
Income tax expense	(31,208)	(731)	(32,045)	(2,611)
Income (loss) from continuing operations	38,183	11,806	7,067	(42,266)
Income from discontinued operations, including gain on sale	0	44,696	0	42,185
Net income (loss)	38,183	56,502	7,067	(81)
Net income attributable to noncontrolling interests	(25)	(621)	(83)	(3,386)
Net income (loss) attributable to the Partnership	38,158	55,881	6,984	(3,467)
General Partner’s interest in net income (loss)	504	697	92	(98)
Limited Partners’ interest in net income (loss)	$ 37,654	$ 55,184	$ 6,892	$ (3,369)
Distribution declared per common unit (in usd per share)	$ 0.1031	$ 0.4125	$ 0.6187	$ 1.2375
Basic:
Income (loss) from continuing operations (in usd per share)	0.56	0.05	(0.34)	(1.35)
Income (loss) from discontinued operations (in usd per share)	0	0.86	0	0.81
Net income (loss) per common unit (in usd per share)	0.56	0.91	(0.34)	(0.54)
Diluted:
Income (loss) from continuing operations (in usd per share)	0.39	0.05	(0.34)	(1.35)
Income (loss) from discontinued operations (in usd per share)	0	0.86	0	0.81
Net income (loss) per common unit (in usd per share)	$ 0.39	$ 0.91	$ (0.34)	$ (0.54)
Weighted average number of common units outstanding:
Weighted average number of common units outstanding: basic (shares)	52,984	52,021	52,917	52,021
Weighted average number of common units outstanding: diluted (shares)	75,525	52,021	52,917	52,021
Commodity sales
Revenue:
Revenue	$ 156,817	$ 124,052	$ 479,923	$ 372,049
Services
Revenue:
Revenue	$ 45,763	$ 38,835	$ 148,997	$ 116,382

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 38,183	$ 56,502	$ 7,067	$ (81)
Unrealized (loss) gain related to postretirement benefit plan	(4)	0	(9)	42
Comprehensive income (loss)	38,179	56,502	7,058	(39)
Comprehensive income attributable to noncontrolling interests	(25)	(621)	(83)	(3,386)
Comprehensive income (loss) attributable to the Partnership	$ 38,154	$ 55,881	$ 6,975	$ (3,425)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Changes in Equity and Partners Capital (Unaudited) - USD ($) $ in Thousands	Total	Panther	Total Partners’ Capital	Total Partners’ CapitalPanther	Accumulated Other Comprehensive Income (Loss)	Non- controlling Interests	Non- controlling InterestsPanther	General Partner Interests	Limited Partner Interests	Limited Partner InterestsPanther
Partners' Capital beginning balance at Dec. 31, 2016	$ 585,157		$ 568,402		$ (40)	$ 16,755		$ (47,645)	$ 616,087
Increase (Decrease) in Partners' Capital [Roll Forward]
Net (loss) income	(81)		(3,467)			3,386		(98)	(3,369)
Contributions	42,270		42,270					38,270	4,000
Distributions	(94,120)		(94,120)					(976)	(93,144)
Contributions from NCI owners	296					296
Distributions to NCI owners	(1,777)					(1,777)
Distribution for acquisition	(75,572)		(75,572)					(75,572)
Issuance of common units for Panther acquisition		$ 12,532		$ 12,532			$ 0			$ 12,532
Acquisition of noncontrolling interest	(28,298)		(23,653)			(4,645)			(23,653)
LTIP vesting	0							(4,633)	4,633
Tax netting repurchase	(1,642)		(1,642)						(1,642)
Equity compensation expense	6,067		6,067					4,430	1,637
Post-retirement benefit plan	42		42		42
Partners' Capital ending balance at Sep. 30, 2017	444,874		430,859		2	14,015		(86,224)	517,081
Increase (Decrease) in Partners' Capital [Roll Forward]
Cumulative effect of accounting change	(10,691)		(10,691)					(139)	(10,552)
Balances at January 1, 2018	180,249		166,488		28	13,761		(96,691)	263,151
Partners' Capital beginning balance at Dec. 31, 2017	190,940		177,179		28	13,761		(96,552)	273,703
Increase (Decrease) in Partners' Capital [Roll Forward]
Net (loss) income	7,067		6,984			83		92	6,892
Contributions	31,786		31,786					31,786	0
Distributions	(74,772)		(74,772)					(978)	(73,794)
Contributions from NCI owners	11					11
Distributions to NCI owners	(75)					(75)
Distribution for acquisition	(38)		(38)					(38)
LTIP vesting	0							(3,954)	3,954
Tax netting repurchase	(1,030)		(1,030)						(1,030)
Equity compensation expense	3,529		3,529					3,529
Post-retirement benefit plan	(9)		(9)
Partners' Capital ending balance at Sep. 30, 2018	$ 146,718		$ 132,938		$ 19	$ 13,780		$ (66,254)	$ 199,173

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities
Net income (loss)	$ 7,067	$ (81)
Adjustments to reconcile net income (loss) to net cash provided by operating activities including discontinued operations:
Depreciation, amortization and accretion, including discontinued operations	66,274	88,700
Amortization of debt issuance costs	5,142	3,610
Amortization of weather derivative premium	797	753
Unrealized (gain) loss on derivatives contracts, net	(5,771)	2,818
Non-cash compensation expense	3,529	6,067
Gain on MPOG acquisition	0	(32,383)
Gain on sale of assets, net of transaction costs, including discontinued operations	(99,491)	(50,580)
Transaction costs associated with disposals of assets and business	(5,842)	(2,545)
Corporate overhead support	0	4,000
Other non-cash items	263	1,805
Earnings in unconsolidated affiliates	(47,742)	(49,781)
Distributions from unconsolidated affiliates	41,775	40,415
Bad debt expense	739	37
Deferred tax (benefit) expense	(6,772)	1,490
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable	7,878	(3,476)
Inventory	(1,222)	(4,011)
Risk management assets and liabilities	(989)	(974)
Other current assets	5,509	10,624
Other assets, net	(4,300)	(1,994)
Accounts payable	8,289	(17,419)
Accrued gas and crude oil purchases	(5,502)	8,805
Accrued expenses and other current liabilities	45,448	9,302
Asset retirement obligations	(2,985)	(603)
Other liabilities	850	426
Net cash provided by operating activities	12,944	15,005
Cash flows from investing activities
Acquisitions, net of cash acquired and settlements	0	(71,383)
Contributions to unconsolidated affiliates	(5,867)	(49,828)
Additions to property, plant and equipment and other	(73,342)	(66,039)
Proceeds from disposals of assets and business	208,572	170,524
Insurance proceeds from involuntary conversion of property, plant and equipment	0	150
Distributions from unconsolidated affiliates, return of capital	22,485	18,562
Net cash provided by investing activities	151,848	1,986
Cash flows from financing activities
Unitholder distributions for common control transactions	0	(75,572)
Contributions	31,786	38,270
Distributions	(66,418)	(88,851)
Contribution from noncontrolling interest owners	11	296
Distributions to noncontrolling interests owners	(75)	(1,777)
LTIP tax netting unit repurchase	(1,030)	(1,642)
Payment of debt issuance costs	(4,701)	(2,234)
Payments of other debt	(4,895)	(3,732)
Payments of credit agreement	(414,500)	(546,408)
Borrowings on credit agreement	316,600	367,809
Other	(71)	86
Net cash used in financing activities	(145,401)	(315,106)
Net increase (decrease) in cash, cash equivalents and restricted cash	19,391	(298,115)
Cash, cash equivalents and restricted cash, beginning of period	34,179	329,230
Cash, cash equivalents and restricted cash, end of period	53,570	31,115
Cash, Cash equivalents and Restricted cash
Cash and cash equivalents (beginning balance)	8,782	5,666
Restricted cash - current (beginning balance)	20,352	0
Restricted cash - non-current (beginning balance)	5,045	323,564
Cash and cash equivalents (ending balance)	22,758	6,739
Restricted cash - current (ending balance)	25,744	18,683
Restricted cash - non-current (ending balance)	5,068	5,693
Long-term Debt | Senior Notes
Cash flows from financing activities
Payment of long-term debt and 3.97% Senior Notes	(792)	(1,351)
3.97% Trans-Union Secured Senior notes | Senior Notes
Cash flows from financing activities
Payment of long-term debt and 3.97% Senior Notes	$ (1,316)	$ 0

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Cash Flows (Parentheticals)	Sep. 30, 2018
3.97% Trans-Union Secured Senior notes | Senior Notes
Debt instrument, stated interest rate (percent)	3.97%

Organization and Basis of Prese

Organization and Basis of Presentation	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	(1) Organization and Basis of Presentation Organization American Midstream Partners, LP (together with its consolidated subsidiaries, the “Partnership,” “we,” “us” or “our”) is a growth-oriented Delaware limited partnership that was formed in August 2009 to own, operate, develop and acquire a diversified portfolio of midstream energy assets. The Partnership’s general partner, American Midstream GP, LLC (the “General Partner”), is 77% directly owned by High Point Infrastructure Partners, LLC (“HPIP”) and 23% indirectly owned by Magnolia Infrastructure Holdings, LLC (“Magnolia”), both of which are affiliates of ArcLight Capital Partners, LLC (“ArcLight”). Our capital accounts consist of notional General Partner units and units representing limited partner interests. We provide critical midstream infrastructure that links producers of natural gas, crude oil, NGLs, condensate and specialty chemicals to numerous intermediate and end-use markets. Through our five reportable segments, (1) Gas Gathering and Processing Services, (2) Liquid Pipelines and Services, (3) Natural Gas Transportation Services, (4) Offshore Pipelines and Services and (5) Terminalling Services, we engage in the business of gathering, treating, processing and transporting natural gas; gathering, transporting, storing, treating and fractionating NGLs; gathering, storing and transporting crude oil and condensates; and storing refined products. Most of our cash flow is generated from fee-based and fixed-margin compensation for gathering, processing, transporting and treating natural gas and crude oil; firm capacity reservation charges; interruptible transportation charges; guaranteed firm storage contracts; throughput fees and other optional charges associated with ancillary services. Basis of presentation The accompanying Condensed Consolidated Financial Statements are unaudited and have been prepared in accordance with Article 10 of Regulation S-X for interim financial information. Accordingly, they do not include all the information and notes required by GAAP for complete financial statements. In the opinion of our management, all adjustments, consisting only of normal recurring adjustments, considered necessary for a fair statement have been included. The results of operations for interim periods are not necessarily indicative of results of operations for a full year. These 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, 2017 filed with the U.S. Securities and Exchange Commission (the “SEC”) on April 9, 2018 (the “2017 Form 10-K”). On April 15, 2013, ArcLight affiliates obtained control of our General Partner. We account for transactions between entities under common control at the affiliate's historical costs. For those transactions, our historical financial statements will be revised to include the results attributable to the assets acquired as if they were acquired on April 15, 2013 or the date the ArcLight affiliates obtained control of the assets or business acquired.

Recent Accounting Pronouncement

Recent Accounting Pronouncements and Critical Accounting Policies	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Recent Accounting Pronouncements and Critical Accounting Policies	(2) Recent Accounting Pronouncements and Critical Accounting Policies Standards Adopted in 2018 Revenue from Contracts with Customers (Topic 606 ) - In May 2014, the Financial Accounting Standards Board (the “FASB”) issued a new standard related to revenue recognition which supersedes most of the existing revenue recognition requirements in GAAP and requires entities to recognize revenue at an amount that reflects the consideration to which an entity expects to be entitled in exchange for transferring goods or services to a customer. It also requires significantly expanded disclosures regarding the qualitative and quantitative information of an entity’s nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. The FASB has issued several amendments to the standard, including clarification on accounting for licenses of intellectual property, identifying performance obligations, reporting gross versus net revenue and narrow-scope revisions, and practical expedients. We adopted the new standard on January 1, 2018 (the “initial application” date): • using the modified retrospective application, with no restatement of the comparative periods presented and a cumulative effect adjustment to retained earnings as of the date of adoption, and • disclosing the impact of the new standard in our Condensed Consolidated Financial Statements included in this report. Our revenue is derived from the provision of gathering, processing, transportation, terminalling and storage services and the sale of commodities primarily to marketers and brokers, refiners and chemical manufacturers, utilities and power generation customers, industrial users and local distribution companies. Beginning on January 1, 2018, we account for revenue from contracts with customers in accordance with Topic 606. The unit of account in Topic 606 is a performance obligation, which is a promise in a contract to transfer to a customer either a distinct good or service (or bundle of goods or services) or a series of distinct goods or services provided at a point in time or over a period of time. Topic 606 requires that a contract’s transaction price, which is the amount of consideration to which an entity expects to be entitled in exchange for transferring promised goods or services to a customer, is to be allocated to each performance obligation in the contract based on relative standalone selling prices and recognized as revenue when (point in time) or as (over time) the performance obligation is satisfied. Commodity Sales - For the majority of our commodity sales contracts: (i) each unit of product is a separate performance obligation, since our promise is to sell multiple distinct units of product at a point in time, (ii) the transaction price principally consists of variable consideration, which is determinable on commodity index prices for the volume of the product sold to the customer that month and (iii) the transaction price is allocated to each performance obligation based on the product’s standalone selling price. Revenues from sales of commodities are recognized at the point in time when control of the commodity transfers to the customer, which generally occurs upon delivery of the product to the customer or its designee. Payment is generally received from the customer in the month following delivery. Contracts with customers have varying terms, including spot sales, month-to-month contracts and multi-year agreements. In our Liquid Pipelines and Services segment, we enter into purchase and sales contracts as well as buy/sell contracts with counterparties, under which we gather and transport different types of crude oil and eventually sell the crude oil to either the same counterparty or different counterparties. For each of these arrangements, the Partnership assesses if control of the underlying commodity volumes transfer to the Partnership. Generally, the Partnership is unable to direct the use of the commodity volumes it purchases from the supplier because the Partnership is contractually required to redeliver an equivalent volume of the commodity back to the supplier or to a specified customer, therefore these arrangements are recorded on a net basis. Occasionally, we enter into crude oil inventory exchange arrangements with the same counterparty where the purchase and sale of inventory are considered in contemplation of each other. These types of arrangements are accounted for as inventory exchanges and are recorded on a net basis. Services - The Partnership provides gathering, processing, transportation, terminalling and storage services pursuant to a variety of contracts. Generally, for the majority of these contracts: (i) our promise is to transfer (or stand ready to transfer) a series of distinct integrated services over a period of time, which is a single performance obligation and (ii) the transaction price includes fixed or variable consideration, or both fixed and variable consideration. The amount of consideration is determinable at contract inception or at each month’s end based on our right to invoice at month end for the value of services provided to the customer in that month. Revenue is recognized over the service period specified in the contract as the services are rendered using a time-based (passage of time) or units-based (units of service transferred) method for measuring provision of the services. Progress towards satisfying our performance obligation is based on the firm or interruptible nature of the promised service and the terms and conditions of the contract (such as contracts with or without makeup rights). Payment is generally received from the customer in the month of service or the month following the service. Contracts with customers generally are a combination of month-to-month and multi-year agreements. Firm Services - Firm services are services that are promised to be available to the customer at all times during the term of the contract with limited exceptions. These agreements require customers to deliver, transport or throughput a minimum volume over an agreed upon period. Substantially all of such agreements are entered into with customers to economically support the return on our capital expenditure necessary to construct the related asset. Our firm service contracts are typically structured with take-or-pay or minimum volume provisions, which specify minimum service quantities a customer will pay for even if it chooses not to receive or use them in the specified service period (referred to as “deficiency quantities”). Under firm service contracts, we record a receivable from the customer in the period that services are provided or when the transaction occurs, including amounts for deficiency quantities from customers associated with minimum volume commitments. If a customer has a make-up right associated with a deficiency, we defer the revenue attributable to the counterparty’s make-up right and subsequently recognize the revenue at the earlier of when the deficiency volume is delivered or shipped, when the make-up right expires or when it is determined that the customer’s ability to utilize the make-up right is remote. Interruptible Services - Interruptible services are services provided to the extent that we have available capacity. Generally, we do not have an obligation to perform these services until we accept a customer’s periodic request for service. For the majority of these contracts, the customer will pay only for the actual quantities of services it chooses to receive or use, and we typically recognize the transaction price as revenue as those units of service are transferred to the customer in the specified service period. Gathering and Processing - Our Gas Gathering and Processing Services segment provides “wellhead-to-market” services to producers of natural gas and natural gas liquids, which include transporting raw natural gas from various receipt points 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. Services can be firm if subject to a minimum volume commitment or acreage dedication or interruptible when offered on an as requested, non-guaranteed basis. Revenue for fee-based gathering and processing services are valued based on the rate in effect for the month of service and is recognized in the month of service based on the volumes of natural gas we gather, process and fractionate. Under these arrangements, we may take control of: (i) none of the commodities we sell (i.e., residue gas or NGLs), (ii) a portion of the commodities we sell or (iii) all of the commodities we sell. In those instances where we purchase and obtain control of the entire natural gas stream in our producer arrangements, we have determined these are contracts with suppliers rather than contracts with customers and therefore, these arrangements are not included in the scope of Topic 606. These supplier arrangements are subject to updated guidance in Accounting Standards Codification (“ASC”) 705, Cost of Sales and Services , whereby any embedded fees within such contracts, which historically have been reported as services revenue, are now reported as a reduction to cost of sales upon adoption of Topic 606. In those instances where we remit all of the cash proceeds received from third parties for selling the extracted commodities to the producer, less the fees attributable to these arrangements, we have determined that the producer has control over these commodities. Upon adoption of Topic 606, we eliminated recording both sales revenue (natural gas and products) and cost of sales amounts and now only record fees attributable to these arrangements as service revenues. In other instances where we do not obtain control of the extracted commodities we sell, we are acting as an agent for the producer and, upon adoption of Topic 606, we have continued to recognize services revenue for the net amount of consideration we retain in exchange for our service. The Partnership may charge additional service fees to customers for a portion of the contract term (i.e., for the first year of a contract or until reaching a volume threshold) due to the significant upfront capital investment, and these fees are initially deferred and recognized to revenue over the expected period of customer benefit, generally the lesser of the expected contract term or the life of the related properties. Transportation - Our transportation operations generally consist of fee-based activities associated with transporting crude oil, natural gas and NGL on pipelines, gathering systems and trucks. Revenues from pipeline tariffs and fees are associated with the transportation at a published tariff, as well as revenues associated with agreements for committed capacity on various assets. We primarily recognize pipeline tariff and fee revenues over time based on the volumes delivered and invoiced. The majority of our pipeline tariff and fee revenues are based on actual volumes and rates. As is common in the pipeline transportation industry, our tariffs incorporate a loss allowance factor. The intent of the allowance in arrangements for the transportation of natural gas is to approximate the natural shrink that occurs when transporting the gas. For crude oil transportation arrangements, loss allowance provisions are immaterial to the Partnership. In the event the Partnership retains excess natural gas and crude oil and subsequently sells the commodity to a third party, the sale is recorded at that point in time as a commodity sale. Terminalling and Storage - In our Terminalling Services segment, we generally receive fee-based compensation on guaranteed firm storage contracts, throughput fees charged to our customers when their products are either received or disbursed, and other operational charges associated with ancillary services provided to our customers, such as excess throughput and steam heating. Storage fees resulting from short-term and long-term contracts are typically recognized in revenue ratably over the term of the contract regardless of the actual storage capacity utilized. Adoption of the new revenue standard resulted in changes to the timing of revenue recognition and in the reclassification between financial statement line items. See Note 3 - Revenue Recognition , for further discussion . Statement of Cash Flows - In August 2016, the FASB issued Accounting Standards Update (“ASU”) No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (“ASU 2016-15”). ASU 2016-15 provides specific guidance on cash flow classification issues to reduce diversity in practice. In connection with the January 1, 2018 retrospective adoption of this ASU, for the nine months ended September 30, 2017, we reclassified $9.4 million in distributions received from unconsolidated affiliates from operating cash inflows to investing cash inflows and reclassified $2.5 million of transaction costs associated the disposal of our Propane Business from an investing cash outflow to an operating cash outflow in our Condensed Consolidated Statements of Cash Flows. In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash (“ASU 2016-18”), which requires amounts described as restricted cash and restricted cash equivalents to be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. A reconciliation between the balance sheet and the statement of cash flows must be disclosed when the balance sheet includes more than one line item for cash, cash equivalents, restricted cash and restricted cash equivalents. We retrospectively adopted ASU 2016-18 as of January 1, 2018. For the nine months ended September 30, 2017, cash flows from operating activities have been adjusted to remove the impact of $3.5 million in restricted cash outflows, and cash flows from investing activities has been adjusted to remove the impact of $302.7 million in restricted cash inflows. During the preparation of our third quarter of 2018 Condensed Consolidated Financial Statements, we identified an error in the presentation of distributions from unconsolidated affiliates in our Condensed Consolidated Statements of Cash Flows in our March 31, 2018 and June 30, 2018 Quarterly Reports on Form 10-Q. This error resulted in the overstatement of net cash provided by operating activities and a corresponding overstatement of net cash used in investing activities of $2.5 million for the three months ended March 31, 2018 and the understatement of net cash provided by operating activities and a corresponding understatement of net cash used in investing activities of $1.0 million for the six months ended June 30, 2018. This error also resulted in a $6.3 million overstatement of net cash provided by operating activities and a corresponding overstatement of net cash used in investing activities for the six months ended June 30, 2017 as presented in the June 30, 2018 Quarterly Report on Form 10-Q. These errors were corrected in the accompanying Condensed Consolidated Statements of Cash Flows for the nine months ended September 30, 2018 and 2017. The errors were not considered material to the previously issued or current financial statements. Stock Compensation - In May 2017, the FASB issued ASU No. 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting (“ASU 2017-09”). ASU 2017-09 was issued with the intent to clarify the scope of modification accounting and when it should be applied to a change to the terms or conditions of a share-based payment award. Under the new guidance, modification accounting is required for all changes to share based payment awards, unless all the following conditions are met: (i) there is no change to the fair value of the award, (ii) the vesting conditions have not changed and (iii) the classification of the award as an equity instrument or a debt instrument has not changed. We adopted ASU 2017-09 on its effective date of January 1, 2018, and the adoption did not have a material impact on our Condensed Consolidated Financial Statements. Income Taxes - In March 2018, the FASB issued ASU No. 2018-05, Income Taxes (Topic 740): Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118 (SEC Update) (“ASU 2018-05”), to provide guidance for companies that have not completed their accounting for the income tax effects of the Tax Cuts and Jobs Act (the “Act”) in the period of enactment. The measurement period begins in the reporting period that includes the Act’s enactment date of December 22, 2017, and ends when a company has obtained, prepared and analyzed the information needed to complete the accounting requirements under ASU 2018-05 and should not extend beyond one year from the enactment date. The impact of adopting the new guidance on our consolidated financial position, cash flows or results of operations, as well as on related disclosures was not material. Standards Not Yet Adopted Leases (Topic 842) - In February 2016, the FASB issued ASU No. 2016-02 (“Topic 842”) Leases , which supersedes the lease recognition requirements in ASC 840, Leases . Under the new guidance, for leases with a term longer than 12 months a lessee should recognize a lease liability and a right-of-use asset representing its right to use the underlying asset for the lease term. Topic 842 retains a classification distinction between finance leases and operating leases, with the classification affecting the pattern of expense recognition in the income statement. This ASU also requires enhanced disclosures. Early adoption is permitted. We are currently assessing the impact of this new guidance via review of existing contracts that may have a lease impact and other purchase obligations that contain embedded lease features, which are generally classified as operating leases under the existing guidance. We selected a third-party consulting firm to assist us with the adoption of the new guidance. We are implementing specialized software and developing policies based on reviews performed to date of existing arrangements. We intend to complete any required changes to our systems, software applications and processes, including updating our internal controls during 2018. In 2018, the FASB also issued ASU No. 2018-01, Land Easement Practical Expedient for Transition to Topic 842 and ASU No. 2018-11, Targeted Improvements . Under these updates, optional transition practical expedients are available i) whereby existing or expired land easements that were not previously accounted for as leases under Topic 840 are not required to be evaluated under Topic 842 and ii) lease and associated non-lease components are not required to be separated within a contract if certain criteria are met. In addition, under ASU No. 2018-11, companies may initially apply the new lease requirements at the effective date. We intend to apply the new lease requirements as of January 1, 2019, recognizing a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption, and to apply the practical expedients. We are still in the process of quantifying the cumulative-effect adjustment. Financial Instruments - In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”). This guidance will become effective for interim and annual periods beginning after December 15, 2019. We expect to adopt ASU 2016-13 on January 1, 2020, and we are currently evaluating the effect that adopting this guidance will have on our consolidated financial position, results of operations and cash flows. Fair Value Measurement - In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurements (Topic 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement (“ASU 2018-13”). This guidance eliminates certain disclosure requirements for fair value measurements for all entities, requires public entities to disclose certain new information and modifies certain disclosure requirements. The FASB developed the amendments to Topic 820 as part of its broader disclosure framework project, which aims to improve the effectiveness of disclosures in the notes to financial statements by focusing on requirements that clearly communicate the most important information to users of the financial statements. This guidance will become effective for interim and annual periods beginning after December 15, 2019. We expect to adopt ASU 2018-13 on January 1, 2020, and we are currently evaluating the impact, if any, that adopting this guidance will have on our disclosures. Cloud Computing Arrangements - In August 2018, the FASB issued ASU No. 2018-15, Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract ("ASU 2018-15"). The ASU aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. The capitalized implementation costs of a hosting arrangement that is a service contract will be expensed over the term of the hosting arrangement. ASU 2018-15 is effective for annual and interim periods beginning after December 15, 2019. Early adoption is permitted, including adoption in any interim period. The amendments can be applied either retrospectively or prospectively to all implementation costs incurred after the adoption date. We expect to adopt ASU 2018-15 on January 1, 2020, and we are currently evaluating the impact, if any, that adopting this guidance will have on our accounting and disclosures. Critical Accounting Policies and Estimates See Item 7 section Critical Accounting Policies and Estimates and Item 1A. Risk Factors of the 2017 Form 10-K for additional information relating to our critical accounting policies and risk factors. Goodwill - We record goodwill for the excess of the cost of an acquisition over the fair value of the net assets of the acquired business. Goodwill is reviewed for impairment at least annually, as of October 1st of each year, or more frequently if an event or change in circumstance indicates that an impairment may have occurred. We first assess qualitative factors to evaluate whether it is more likely than not that an impairment has occurred, and it is therefore necessary to perform the one-step quantitative goodwill impairment test. If the one-step quantitative goodwill impairment test indicates that the goodwill is impaired, an impairment loss is recorded, which is the difference between carrying value of the reporting unit and its fair value, with the impairment loss not to exceed the amount of goodwill recorded. When performing a quantitative impairment test, the Partnership generally determines the fair value of its reporting units using a discounted cash flow method. In the event the Partnership enters into an agreement to sell all or substantially all of a reporting unit, the Partnership will utilize such information. While using the discounted cash flow method, we must make estimates of projected cash flows related to assets, which include, but are not limited to, assumptions about revenue growth rates, operating margins, weighted average costs of capital and future market conditions, the use or disposition of assets, estimated remaining life of assets and future expenditures necessary to maintain current operations. We also must make certain estimates and assumptions, including, among other things, changes in general economic conditions in regions in which our markets are located, the availability and prices of energy commodities (such as natural gas, crude oil and refined products), our ability to negotiate favorable sales agreements, the risks that natural gas exploration and production activities will not occur or be successful, our dependence on certain significant customers and producers of natural gas and competition from other companies. Under the discounted cash flow method, the Partnership determines fair value based on estimated future cash flows and earnings before income tax, depreciation and amortization (“EBITDA”) of each reporting unit including estimates for capital expenditures, discounted to present value using the risk-adjusted industry rate, which reflects the overall level of inherent risk of the reporting unit. Cash flow projections are derived from one-year budgeted amounts and five-year operating forecasts plus an estimate of later period cash flows, all of which are evaluated by management. Subsequent period cash flows are developed for each reporting unit using growth rates that management believes are reasonably likely to occur. The annual budget process is typically completed near the annual goodwill impairment testing date, and management uses the most recent information for the annual impairment tests. The forecast is also subjected to a comprehensive update annually in conjunction with the annual budget process and is revised periodically to reflect new information and revised expectations. The estimates of future cash flows and EBITDA are subjective in nature and are subject to impacts from the business risks described in Item 1A. Risk Factors of the 2017 Form 10-K. While we believe we have made reasonable estimates and assumptions based on available information to calculate the fair value, if future results are not consistent with our estimates, changes in fair value estimates could result in additional impairments in future periods that could be material to our results of operations. As of December 31, 2017, we had $128.9 million of goodwill within seven reporting units. Of this amount, $46.8 million of goodwill for two reporting units was at risk of failing the one-step quantitative test. Our Silver Dollar reporting unit in our Liquid Pipelines and Services segment had $35.7 million in goodwill as of December 31, 2017. As described in Note 10 - Goodwill and Intangible Assets, Net in our 2017 Form 10-K, we recorded an impairment on the Silver Dollar reporting unit during the fourth quarter of 2017; therefore, the fair value approximates the carrying value subsequent to impairment. The impairment taken in 2017 related primarily to cash flow assumptions included in our discounted cash flow analysis that were adversely impacted by delays in drilling and completions experienced by producers. The Cushing reporting unit in our Terminalling Services segment had $11.1 million in goodwill as of December 31, 2017, and the fair value exceeded carrying value by approximately 7% . In our discounted cash flow analysis for 2017, we assumed lower utilization rates and cash flows due to required tank inspections through early 2019. The lower utilization was not previously expected, or reflected, in our assumptions. If the expected completion date of the inspections or future contracting rates should differ from the assumptions made in our 2017 analysis, the amount by which the estimated fair value exceeds carrying value could be negatively impacted. As of September 30, 2018, we had $51.7 million of goodwill within three reporting units in our Condensed Consolidated Balance Sheet and $61.2 million of goodwill within two reporting units classified as held for sale. There were no triggering events during the nine months ended September 30, 2018 and, therefore, we have not quantitatively updated our assessments. We will perform our annual impairment test for goodwill as of October 1, 2018.

Revenue Recognition

Revenue Recognition	9 Months Ended
	Sep. 30, 2018
Revenue from Contract with Customer [Abstract]
Revenue Recognition	(3) Revenue Recognition Effect of ASC Topic 606 Adoption - The effect of adopting Topic 606, due to the change in method to measure project progress, as discussed in Note 2 - Recent Accounting Pronouncements, is as follows (in thousands): Three months ended September 30, 2018 Nine months ended September 30, 2018 As Reported Adjustments Amounts Without Adoption of Topic 606 As Reported Adjustments Amounts Without Adoption of Topic 606 Revenue Commodity sales $ 156,817 $ 10,388 $ 167,205 $ 479,923 $ 28,165 $ 508,088 Services 45,763 (9,965 ) 35,798 148,997 (24,890 ) 124,107 Operating expenses Costs of sales 150,274 6,349 156,623 461,948 14,923 476,871 Direct operating expenses 20,407 (5,248 ) 15,159 65,595 (10,254 ) 55,341 Operating income 67,164 (678 ) 66,486 47,142 (1,394 ) 45,748 Net income attributable to the Partnership 38,158 (678 ) 37,480 6,984 (1,394 ) 5,590 General Partner’s interest in net income 504 (9 ) 495 92 (18 ) 74 Limited Partners’ interest in net income 37,654 (669 ) 36,985 6,892 (1,376 ) 5,516 As of September 30, 2018 As Reported Adjustments Amounts Without Adoption of Topic 606 Assets Accounts receivable, net $ 84,819 $ (66,250 ) $ 18,569 Unbilled revenue — 66,250 66,250 Other current assets 25,971 (252 ) 25,719 Other assets, net 21,506 (7,785 ) 13,721 Liabilities Accrued expenses and other current liabilities 116,141 (905 ) 115,236 Liabilities held for sale 1,922 (665 ) 1,257 Other long-term liabilities 15,770 (14,110 ) 1,660 The majority of the adjustments in the table above were associated with our natural gas gathering and processing, transportation pipeline and terminalling revenues. The magnitude of the future effect of implementing Topic 606 is dependent on future customer volumes subject to the impacted contracts and commodity prices for those volumes. Disaggregated Revenue The following table presents our segment revenues from contracts with customers disaggregated by type of activity (in thousands): Three months ended September 30, 2018 Gas Gathering and Processing Services Liquid Pipelines and Services Natural Gas Transportation Services Offshore Pipelines and Services Terminalling Services Total Commodity sales: Natural gas $ 2,672 $ — $ 5,988 $ 2,207 $ — $ 10,867 NGLs 24,338 — — 54 — 24,392 Condensate 14,994 — — 343 — 15,337 Crude oil — 104,984 — — — 104,984 Other sales (1) 365 — 1 19 852 1,237 42,369 104,984 5,989 2,623 852 156,817 Services: Gathering and processing 10,164 — — 969 — 11,133 Transportation 241 4,540 6,565 10,203 — 21,549 Terminalling and storage — — — — 6,410 6,410 Other services (2) 655 35 156 5,536 289 6,671 11,060 4,575 6,721 16,708 6,699 45,763 Revenues from contracts with customers $ 53,429 $ 109,559 $ 12,710 $ 19,331 $ 7,551 $ 202,580 Nine months ended September 30, 2018 Gas Gathering and Processing Services Liquid Pipelines and Services Natural Gas Transportation Services Offshore Pipelines and Services Terminalling Services Total Commodity sales: Natural gas $ 8,099 $ — $ 18,098 $ 7,231 $ — $ 33,428 NGLs 63,547 — — 125 — 63,672 Condensate 34,796 — — 440 — 35,236 Crude oil — 337,281 — — — 337,281 Other sales (1) 690 — 7 83 9,526 10,306 107,132 337,281 18,105 7,879 9,526 479,923 Services: Gathering and processing 29,370 — — 874 — 30,244 Transportation 489 11,754 25,833 29,092 — 67,168 Terminalling and storage — — — — 30,393 30,393 Other services (2) 1,622 912 401 16,866 1,391 21,192 31,481 12,666 26,234 46,832 31,784 148,997 Revenues from contracts with customers $ 138,613 $ 349,947 $ 44,339 $ 54,711 $ 41,310 $ 628,920 _________________________ (1) Other commodity sales for our Terminalling Services segment include sales of Refined Products and Marine Products terminals. See Note 4 - Acquisitions and Dispositions. (2) Other services in our Offshore Pipelines and Services segment include asset management services. Other Items in Revenue The following table presents the reconciliation of our revenues from contracts with customers to segment revenues and total revenues as disclosed in our Condensed Consolidated Statements of Operations (in thousands): Three months ended September 30, 2018 Gas Gathering and Processing Services Liquid Pipelines and Services Natural Gas Transportation Services Offshore Pipelines and Services Terminalling Services Total Revenues from contracts with customers $ 53,429 $ 109,559 $ 12,710 $ 19,331 $ 7,551 $ 202,580 Loss on commodity derivatives, net (93 ) (141 ) — — — (234 ) Total revenues of reportable segments $ 53,336 $ 109,418 $ 12,710 $ 19,331 $ 7,551 $ 202,346 Nine months ended September 30, 2018 Gas Gathering and Processing Services Liquid Pipelines and Services Natural Gas Transportation Services Offshore Pipelines and Services Terminalling Services Total Revenues from contracts with customers $ 138,613 $ 349,947 $ 44,339 $ 54,711 $ 41,310 $ 628,920 Loss on commodity derivatives, net (385 ) (145 ) — — — (530 ) Total revenues of reportable segments $ 138,228 $ 349,802 $ 44,339 $ 54,711 $ 41,310 $ 628,390 We may utilize derivative instruments in connection with contracts with customers. We purchase and take title to a portion of the NGLs and crude oil that we sell, which may expose us to changes in the price of these products in our sales markets. We do not take title to the natural gas we transport and therefore have no direct commodity price exposure to natural gas. Derivative gains or losses are not included as a component of revenue from contracts with customers, but are included in other items in revenue. Contract Balances Our contract assets and liabilities primarily relate to contracts where allocations of the transaction prices result in differences to the pattern and timing of revenue recognition as compared to contractual billings. Where payments are received in advance of recognition as revenue, contract liabilities are created. Where we have earned revenue and our right to invoice the customer is conditioned on something other than the passage of time, contract assets are created. The following table presents the change in the contract assets and liability balances during the nine months ended September 30, 2018 (in thousands): Contract Assets Contract Liabilities Balance at December 31, 2017 $ — $ 2,136 Topic 606 implementation 2,555 13,246 Amounts recognized as revenue — (2,155 ) Additions 5,482 3,250 Contract balances included in assets/liabilities held for sale — (665 ) Balances at September 30, 2018 $ 8,037 $ 15,812 Current $ 252 $ 905 Non-current 7,785 14,907 Balances at September 30, 2018 $ 8,037 $ 15,812 As of September 30, 2018 , in our Condensed Consolidated Balance Sheets, the current portion of contract assets is included as a component of Accounts Receivable, net of allowance for doubtful accounts , the non-current portion is included in Other assets, net ; the current portion of contract liabilities is included in Accrued expenses and other current liabilities and the non-current portion is included in Other long-term liabilities . Remaining Performance Obligations The Partnership applies the practical expedients in Topic 606 and does not disclose consideration for remaining performance obligations with an original expected duration of one year or less or for variable consideration related to unsatisfied (or partially unsatisfied) performance obligations. The following table as of September 30, 2018 , represents only revenue expected to be recognized from contracts where the price and quantity of the product or service are fixed: Remainder of 2018 2019 2020 2021 2022 Thereafter Total Gathering and processing based on minimum volume commitments $ 3,065 $ 12,667 $ 12,667 $ 12,644 $ 12,391 $ 18,289 $ 71,723 Transportation agreements 5,523 19,604 18,690 18,507 18,428 193,484 274,236 Terminalling and storage throughput agreements (1) 972 3,644 2,419 2,113 1,005 — 10,153 Other 423 1,648 1,560 — — — 3,631 Total $ 9,983 $ 37,563 $ 35,336 $ 33,264 $ 31,824 $ 211,773 $ 359,743 _________________________ (1) Represents remaining performance obligations associated with assets held-for-sale . Due to the application of the practical expedients, the table above represents only a portion of the Partnership’s expected future consolidated revenues and it is not necessarily indicative of the expected trend in total revenues for the Partnership. Certain contracts have not been presented in the table above due to the term being one year or less and due to variability in the amount of performance obligation remaining, variability in the timing of recognition or variability in consideration. Acreage dedications do require us to perform future services but do not contain a minimum level of services and are therefore excluded from this presentation. Long-term supply and logistics arrangements contain variable timing, volumes and/or consideration and are excluded from this presentation.

Acquisitions and Dispositions

Acquisitions and Dispositions	9 Months Ended
	Sep. 30, 2018
Discontinued Operations and Disposal Groups [Abstract]
Acquisition and Dispositions	(4) Acquisitions and Dispositions Acquisitions The 2017 acquisitions are as follows: • On March 8, 2017, we completed the acquisition of JP Energy Partners LP (“JPE”), an entity controlled by ArcLight affiliates, in a unit-for-unit exchange. As both we and JPE were controlled by ArcLight affiliates, the acquisition represented a transaction among entities under common control. The accompanying Condensed Consolidated Financial Statements and related Notes present the combined financial position, results of operations, cash flows and equity of JPE at historical cost. • On June 2, 2017, we acquired 100% of Viosca Knoll Gathering System (“VKGS”) from Genesis Energy, L.P. for total consideration of approximately $32 million in cash. This was accounted for as a business combination. • On August 8, 2017, we acquired 100% of the interest in Panther Offshore Gathering Systems, LLC (“POGS”), Panther Pipeline, LLC (“PPL”) and Panther Operating Company, LLC (“POC” and, together with POGS and PPL, “Panther”) from Panther Asset Management LLC for $60.9 million in cash, issuance of common units and other considerations. This was accounted for as a business combination. • On November 3, 2017, we completed the acquisition of 100% of the equity interests in Trans-Union Interstate Pipeline, LP (“Trans-Union”) from affiliates of ArcLight, for a total consideration of $49.4 million . The consideration consisted of $16.9 million cash funded from borrowings under our revolving credit facility and the assumption of $32.5 million of non-recourse debt. This was accounted for as an acquisition between entities under common control. Additionally, we acquired the following interests in 2017 that are accounted for as investments in unconsolidated affiliates: • On August 8, 2017, we entered into a new joint venture agreement with Targa Midstream Services, LLC (“Targa”) by which our previously wholly owned subsidiary Cayenne Pipeline, LLC became the Cayenne joint venture between Targa and us. • On September 29, 2017, we acquired an additional 15.5% equity interest in Class A units of the Delta House platform (“Delta House”) from affiliates of ArcLight for total cash consideration of $125.4 million . • On October 27, 2017, American Midstream Emerald, LLC, a wholly-owned subsidiary of the Partnership, entered into a purchase and sale agreement with Emerald Midstream, LLC, an ArcLight affiliate, to purchase an additional 17% equity interest in Destin for total cash consideration of $30.0 million . For further discussion, see the Note 3 - Acquisitions in our 2017 Form 10-K. The proforma effects of the 2017 acquisitions were not material to our Condensed Consolidated Statements of Operations and therefore have not been presented separately. Southcross Energy Partners, L.P. Merger Termination Fee On October 31, 2017, we, our General Partner, our wholly owned subsidiary, Cherokee Merger Sub LLC, Southcross Energy Partners, L.P. (“SXE”) and Southcross Energy Partners GP, LLC, entered into an Agreement and Plan of Merger (the “SXE Merger Agreement”), and we, our General Partner and Southcross Holdings LP (“Holdings LP”) entered in to a Contribution Agreement (“Contribution Agreement”), for total consideration of $818 million . Under the Merger Agreement and the Contribution Agreement, we would have acquired SXE and substantially all the current subsidiaries of Holdings LP. The SXE Merger Agreement and the Contribution Agreement originally provided for an outside closing date of June 1, 2018. On June 1, 2018 the parties to the Merger Agreement and the Contribution Agreement agreed to extend such outside closing date to June 15, 2018 (the “Outside Closing Date”). On July 29, 2018, following the expiration of the Outside Closing Date, we received notice of termination of the SXE Merger Agreement from SXE and notice of termination of the Contribution Agreement from Holdings LP. The terms of the Contribution Agreement required the payment to Holdings LP of a $17 million termination fee in the event Holdings LP terminated the Contribution Agreement after the Outside Closing Date due to our inability to obtain financing to close the SXE Transactions on terms reasonably acceptable to us. The termination fee serves as liquidated damages, was paid in August 2018 and is presented as Termination fee in the Condensed Consolidated Statements of Operations. Dispositions On June 16, 2018, we entered into a definitive agreement for the sale of our marine liquids terminals (the “Marine Products”) to institutional investors. The divestiture of the Marine Products, including the Harvey and Westwego terminals located in the Port of New Orleans, Louisiana and the Brunswick terminal located in the Port of Brunswick, Georgia, is a continuation of the Partnership's previously announced non-core asset divestiture program. On July 31, 2018, we completed the sale of Marine Products. Net proceeds from this disposition were $208.6 million , exclusive of $5.7 million in advisory fees and other costs, and were used to pay down the Credit Agreement (as defined in Note 13 - Debt Obligations ). We recognized a $99.4 million gain, which is reflected in the Gain on Sale of Assets, Net in our Condensed Consolidated Statements of Operations. The tax expense associated with the gain was approximately $29.8 million and is included in Income tax expense in the Condensed Consolidated Statements of Operations. The sale of Marine Products did not meet the criteria for discontinued operations, as we believe the disposal does not represent a strategic shift that will have a major effect on our operations or financial results. Assets Held for Sale In the second quarter of 2017, we began executing a capital optimization strategy to simplify our business and redeploy capital from non-core assets toward higher return and growth opportunities. In addition to the sale of our propane business (“Propane Business”) discussed below under Discontinued Operations , we determined that our terminalling assets were not integral to our core strategies, and therefore, we began contemplating their disposition. We began actively marketing our Terminalling Services segment assets to use the proceeds to fund future acquisitions and growth projects. On February 16, 2018, we entered into a definitive agreement for the sale of our refined products terminals (the “Refined Products”) to DKGP Energy Terminals LLC (“DKGP”), for $138.5 million in cash, subject to working capital adjustments. On August 1, 2018, we, and DKGP, announced the termination of the sales agreement for our Refined Products. We are continuing to market Refined Products. The planned disposition of the Refined Products terminals does not meet the criteria for discontinued operations, as we believe the disposal does not represent a strategic shift that will have a major effect on our operations or financial results. As of September 30, 2018, Refined Products assets and liabilities are classified as current assets held for sale and current liabilities held for sale consistent with the classification of our revolving credit facility which matures September 5, 2019, as the net cash proceeds received from the sale are required to be repaid and reduce the aggregate commitments of our revolving credit facility. See Note 13 - Debt Obligations for more information. As of September 30, 2018, certain remaining assets in the Terminalling Services segment do not meet the criteria to be classified as held for sale, and are therefore excluded from being presented as held for sale. Included in the disposal group are the following assets and liabilities at September 30, 2018 (in thousands): Refined Products Accounts receivable, net $ 2,170 Inventory 762 Other current assets 131 Property, plant and equipment, net 32,390 Goodwill 61,163 Intangible assets 29,403 Other non-current assets 671 Total assets held for sale $ 126,690 Accounts payable $ 227 Accrued gas purchases 108 Accrued expenses and other current liabilities 1,097 Other long-term liabilities 490 Total liabilities held for sale $ 1,922 Discontinued Operations On September 1, 2017, we completed the disposition of our Propane Business pursuant to the Membership Interest Purchase Agreement dated July 21, 2017, between AMID Merger LP, a wholly owned subsidiary of the Partnership, and SHV Energy N.V. Through the transaction, we divested Pinnacle Propane’s 40 service locations; Pinnacle Propane Express’ cylinder exchange business and related logistics assets; and the Alliant Gas utility system. Prior to the sale, we moved the trucking business from the Propane Marketing Services segment to the Liquid Pipelines and Services segment. With the disposition of the Propane Business, we eliminated the Propane Marketing Services segment. In connection with the transaction, we received approximately $170 million in cash, net of customary closing adjustments. We recorded a gain of $46.5 million , exclusive of of $2.5 million in advisory fees and other costs. We have reported the accounts and the results of our Propane Business, including the gain on sale, as Income from discontinued operations, including gain on sale in our Condensed Consolidated Statements of Operations for the three and nine months ended September 30, 2017 . Summarized financial information related to the Propane Business is set forth in the tables below (in thousands): Three months ended September 30, 2017 Nine months ended September 30, 2017 Total revenue $ 20,458 $ 87,615 Total operating expenses 22,489 92,196 Operating loss (2,031 ) (4,581 ) Other income 197 280 Income tax expense (15 ) (59 ) Loss from discontinued operations (1,849 ) (4,360 ) Gain from the sale of discontinued operations 46,545 46,545 Income from discontinued operations, including gain on sale $ 44,696 $ 42,185 Depreciation and amortization $ 2,355 $ 9,823 Capital expenditures $ 722 $ 3,143 Operating and investing non-cash items related to discontinued operations: (Gain) loss on sales of assets, net $ 118 $ (55 ) Unrealized loss on derivative contracts, net $ (526 ) $ 530

Inventory (Notes)

Inventory (Notes)	9 Months Ended
	Sep. 30, 2018
Inventory Disclosure [Abstract]
Inventory	(5) Inventory Inventory consists of the following (in thousands): September 30, 2018 December 31, 2017 Crude oil $ 2,416 $ 1,553 NGLs 544 347 Refined products — 934 Materials, supplies and equipment 120 132 Total inventory $ 3,080 $ 2,966

Other Current Assets

Other Current Assets	9 Months Ended
	Sep. 30, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Other Current Assets	(6) Other Current Assets Other current assets consist of the following (in thousands): September 30, 2018 December 31, 2017 Prepaid expenses $ 6,049 $ 8,944 Current portion of deferred debt issuance costs (1) 5,057 — Insurance receivables 649 1,741 Due from related parties 2,461 4,362 Other receivables 4,520 5,187 Risk management assets 7,235 3,186 Total other current assets $ 25,971 $ 23,420 ___________________________________________________ (1) Related to our Credit Agreement. See Note 13 - Debt Obligations for discussion of our debt obligations.

Risk Management Activities

Risk Management Activities	9 Months Ended
	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Risk Management Activities	(7) Risk Management Activities We are exposed to certain market risks related to the volatility of commodity prices and changes in interest rates. To monitor and manage these market risks, we have established comprehensive risk management policies and procedures. We do not enter into derivative instruments for any purpose other than hedging commodity price risk, interest rate risk and weather risk. We do not speculate using derivative instruments. Commodity Derivatives To manage the impact of the risks associated with changes in the market price of NGL, crude oil and refined products in our day-to-day business, we use a combination of fixed price swaps and forward contracts. Our forward contracts that qualify for the Normal Purchase Normal Sale (“NPNS”) exception under GAAP are recognized when the underlying commodity is delivered . In accordance with ASC 815, Derivatives and Hedging, if it is determined that a transaction designated as NPNS no longer meets the scope of the exception, the fair value of the related contract is recorded on the balance sheet (as an asset or liability) and the difference between the fair value and the contract amount is immediately recognized through earnings. We measure our commodity derivatives at fair value using the income approach, which discounts the future net cash settlements expected under the derivative contracts to a present value. These valuations utilize indirectly observable (“Level 2”) inputs, including commodity prices observable at commonly quoted intervals. The following table summarizes the net notional volumes of our outstanding commodity-related derivatives, excluding those contracts that qualified for the NPNS exception as of September 30, 2018 and December 31, 2017 , none of which were designated as hedges for accounting purposes. We had no outstanding commodity-related derivatives as of December 31, 2017 . September 30, 2018 December 31, 2017 Commodity Swaps Volume Maturity Volume Maturity NGLs Fixed Price (gallons) 831,600 January 2019 — — Crude Oil Basis (barrels) 93,000 December 2018 — — Interest Rate Swaps To manage the impact of the interest rate risk associated with our Credit Agreement, we enter into interest rate swaps from time to time, effectively converting a portion of the cash flows related to our long-term variable rate debt into fixed rate cash flows. As of both September 30, 2018 and December 31, 2017 , we had a combined notional principal amount of $550.0 million of variable-to-fixed interest rate swap agreements. As of September 30, 2018 , the maximum length of time over which we have hedged a portion of our exposure due to interest rate risk is through December 31, 2022. The fair value of our interest rate swaps was estimated using a valuation methodology based upon forward interest rates and 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, which represent Level 2 inputs in the valuation hierarchy, are obtained from independent pricing service providers, and we have made no adjustments to those prices. Weather Derivative In the second quarters of 2018 and 2017, we entered into a yearly weather derivative arrangement to mitigate the impact of potential unfavorable weather on our operations under which we could receive payments totaling up to $20.0 million and $30.0 million , respectively, in the event that a hurricane of certain strength passes through the areas identified in the derivative agreement. The weather derivative, which is accounted for using the intrinsic value method, was entered into with a single counterparty, and we were not required to post collateral. We paid $1.0 million and $1.1 million in premiums during the nine months ended September 30, 2018 and 2017, respectively. Premiums are amortized to Direct operating expenses on a straight-line basis over the one -year term of the contract. Unamortized amounts associated with the weather derivatives were $0.7 million and $0.5 million as of September 30, 2018 and December 31, 2017 , respectively, and are included in Other current assets on the Condensed Consolidated Balance Sheets. Financial Instruments Measured at Fair Value on a Recurring Basis - The following table summarizes the fair values of our derivative contracts (before netting adjustments) included in the Condensed Consolidated Balance Sheets (in thousands): Asset Derivatives Liability Derivatives Type Balance Sheet Classification September 30, December 31, 2017 September 30, December 31, 2017 Commodity derivatives Accrued expenses and other current liabilities $ — $ — $ (352 ) $ — Interest rate swaps Other current assets 6,534 2,677 — — Interest rate swaps Other assets, net 11,074 8,807 — — Weather derivatives Other current assets 701 509 — — Total $ 18,309 $ 11,993 $ (352 ) $ — As of September 30, 2018 and December 31, 2017, there were no offsets to the fair value of our derivative assets and liabilities on a gross basis in the Condensed Consolidated Balance Sheets subject to enforceable master netting arrangements. For each of the three and nine months ended September 30, 2018 and 2017 , the realized and unrealized gains (losses) associated with our commodity, interest rate and weather derivative instruments were recorded in our Condensed Consolidated Statements of Operations as follows (in thousands): Three months ended September 30, Nine months ended September 30, Realized Unrealized Realized Unrealized 2018 Loss on commodity derivatives, net $ (122 ) $ (112 ) $ (178 ) $ (352 ) Interest expense, net of capitalized interest 341 33 2,976 6,123 Direct operating expenses (247 ) — (797 ) — 2017 Loss on commodity derivatives, net $ (51 ) $ (546 ) $ 465 $ (498 ) Interest expense, net of capitalized interest 51 221 (19 ) (1,790 ) Direct operating expenses (278 ) — (753 ) — Fair Value Financial Instruments Not Measured at Fair Value on a Recurring Basis - The following table presents the carrying value and estimated fair value of our financial instruments that are not measured at fair value on a recurring basis as of September 30, 2018 and December 31, 2017. Short-term and long-term debt are recorded at amortized cost in the Condensed Consolidated Balance Sheets. September 30, 2018 December 31, 2017 Carrying Amount Fair Value Carrying Amount Fair Value Non-Derivatives Liabilities 8.5% Senior Unsecured Notes $ 418,989 $ 427,154 $ 418,421 $ 437,062 3.77% Senior Secured Notes 55,342 49,792 56,005 53,845 3.97% Trans-Union Secured Senior Notes 30,390 27,118 31,692 30,221 Total $ 504,721 $ 504,064 $ 506,118 $ 521,128 The fair value of debt instruments are valued using a market approach based on quoted prices for similar instruments traded in active markets and are classified as Level 2 within the fair value hierarchy. All financial instruments in the table above are classified as Level 2. The carrying value of amounts outstanding under the Credit Agreement approximates the related fair value, as interest charges vary with market rate conditions. The carrying value of all non-derivative financial instruments included in current assets (including cash, cash equivalents, restricted cash and accounts receivable) and current liabilities (including accounts payable but excluding short-term debt) approximates the applicable fair value due to the short maturity of those instruments.

Property, Plant and Equipment

Property, Plant and Equipment	9 Months Ended
	Sep. 30, 2018
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	(8) Property, Plant and Equipment Property, plant and equipment, net, consists of the following (in thousands): Useful Life (in years) September 30, December 31, Land Infinite $ 14,635 $ 18,145 Construction in progress N/A 54,584 55,622 Buildings and improvements 4 to 40 10,116 16,235 Transportation equipment 5 to 15 22,527 22,697 Processing and treating plants 8 to 40 123,901 123,138 Pipelines, compressors and right-of-way 3 to 40 1,022,034 974,301 Storage 3 to 40 44,418 146,105 Equipment 3 to 31 62,062 80,220 Total property, plant and equipment 1,354,277 1,436,463 Accumulated depreciation (360,357 ) (340,878 ) Property, plant and equipment, net $ 993,920 $ 1,095,585 At September 30, 2018 and December 31, 2017 , gross property, plant and equipment included $376.4 million and $367.6 million , respectively, related to FERC regulated interstate and intrastate assets. Depreciation expense totaled $17.6 million and $20.1 million for the three months ended September 30, 2018 and 2017 , respectively, and $54.4 million and $56.9 million for the nine months ended September 30, 2018 and 2017 , respectively. Capitalized interest was $0.7 million and $0.5 million for the three months ended September 30, 2018 and 2017 , respectively, and $2.2 million and $2.0 million for the nine months ended September 30, 2018 and 2017 , respectively.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	9 Months Ended
	Sep. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	(9) Goodwill and Intangible Assets Goodwill consists of the following (in thousands): September 30, 2018 December 31, 2017 Liquid Pipelines and Services $ 35,708 $ 35,708 Terminalling Services 11,043 88,466 Offshore Pipelines and Services 4,972 4,692 Total $ 51,723 $ 128,866 The decline in goodwill in our Terminalling Services segment relates to Marine Products which were sold on July 31, 2018 and Refined Products which were classified as held for sale at September 30, 2018 . See Note 4 - Acquisitions and Dispositions for further discussion. Intangible assets, net, consist of the following (in thousands): September 30, 2018 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Customer relationships $ 64,745 $ (16,290 ) $ 48,455 Customer contracts 94,693 (51,910 ) 42,783 Dedicated acreage 42,546 (7,248 ) 35,298 Collaborative arrangements 11,884 (2,051 ) 9,833 Noncompete agreements 1,064 (1,064 ) — Other 197 (29 ) 168 Total $ 215,129 $ (78,592 ) $ 136,537 December 31, 2017 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Customer relationships $ 110,483 $ (29,965 ) $ 80,518 Customer contracts 94,692 (48,173 ) 46,519 Dedicated acreage 42,547 (6,216 ) 36,331 Collaborative arrangements 11,884 (1,415 ) 10,469 Noncompete agreements 1,064 (1,064 ) — Other 198 (25 ) 173 Total $ 260,868 $ (86,858 ) $ 174,010 These intangible assets have definite lives and are subject to amortization on a straight-line basis over their economic lives, currently ranging from approximately 5 years to 30 years . Amortization expense related to our intangible assets totaled $2.5 million and $6.4 million for the three months ended September 30, 2018 and 2017 , respectively, and $7.8 million and $20.6 million for the nine months ended September 30, 2018 and 2017 , respectively. The estimated aggregate annual amortization expected to be recognized for the remainder of 2018 and each of the four succeeding fiscal years is $2.5 million , $10.2 million , $10.2 million , $10.2 million and $9.3 million , respectively.

Investment in Unconsolidated Af

Investment in Unconsolidated Affiliates	9 Months Ended
	Sep. 30, 2018
Equity Method Investments and Joint Ventures [Abstract]
Investment in Unconsolidated Affiliates	(10) Investments in Unconsolidated Affiliates The following table presents the activity in our equity method investments in unconsolidated affiliates (in thousands): Delta House (1) Emerald Transactions FPS (2,4) OGL (2,4) Destin (4) Tri-States (3) Okeanos (4) Wilprise (3) Cayenne JV (3) Total Ownership % - December 31, 2017 35.7% 35.7% 66.7% 16.7% 66.7% 25.3% 50.0% Ownership % - September 30, 2018 35.7% 35.7% 66.7% 16.7% 66.7% 25.3% 50.0% Balances at December 31, 2017 $ 90,412 $ 46,932 $ 124,245 $ 53,057 $ 22,445 $ 4,689 $ 6,654 $ 348,434 Earnings in unconsolidated affiliates 14,892 8,204 8,543 2,983 8,225 664 4,231 47,742 Contributions 847 6 — — — — 4,020 4,873 Distributions (11,256 ) (12,076 ) (21,980 ) (4,701 ) (11,499 ) (848 ) (1,900 ) (64,260 ) Balances at September 30, 2018 $ 94,895 $ 43,066 $ 110,808 $ 51,339 $ 19,171 $ 4,505 $ 13,005 $ 336,789 ___________________________________________________ (1) Represents direct and indirect ownership interests in Class A units and common units. (2) FPS denotes Floating Production System LLC whereas OGL denotes Oil & Gas Lateral LLC. (3) Included in our Liquid Pipelines and Services segment. (4) Included in our Offshore Pipelines and Services segment. The following tables present the summarized combined financial information for our equity investments (amounts represent 100% of investee financial information) (in thousands): Balance Sheets: September 30, 2018 December 31, 2017 Current assets $ 88,702 $ 80,405 Non-current assets 1,257,275 1,288,862 Current liabilities 86,821 130,904 Non-current liabilities 470,391 436,584 Three months ended September 30, Nine months ended September 30, Statements of Operations: 2018 2017 (1) 2018 2017 (1) Revenue $ 85,504 $ 105,621 $ 194,193 $ 308,987 Operating expenses 6,665 24,168 21,172 76,145 Net income 63,078 76,650 123,226 220,617 _________________________ (1) In August 2017, we acquired 100% of the interest in POGS, the outstanding interests in one of our equity investments. We have consolidated this entity from the acquisition date. See Note 4 - Acquisitions and Dispositions for further discussion.

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	9 Months Ended
	Sep. 30, 2018
Other Liabilities Disclosure [Abstract]
Accrued Expenses and Other Current Liabilities	(11) Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consists of the following (in thousands): September 30, 2018 December 31, 2017 Capital expenditures $ 9,069 $ 10,721 Accrued interest 14,290 3,190 Convertible preferred unit distributions 8,354 — Current portion of asset retirement obligation 3,764 6,416 Additional Blackwater acquisition consideration (see Note 19) 5,000 5,000 Taxes payable 42,350 5,263 Due to related parties 9,508 6,609 Royalties, gas imbalance and leases payables 5,734 7,905 Professional fees 4,587 1,848 Other 13,485 21,902 Total accrued expenses and other current liabilities $ 116,141 $ 68,854 The increase in taxes payable from period to period is primarily due to income taxes associated with our sale of Marine Products in the third quarter of 2018. See further discussion of the Marine Products sale in Note 4 - Acquisitions and Dispositions .

Asset Retirement Obligations

Asset Retirement Obligations	9 Months Ended
	Sep. 30, 2018
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligations	(12) Asset Retirement Obligations We record a liability for the fair value of asset retirement obligations and conditional asset retirement obligations (collectively referred to as “AROs”) that we can reasonably estimate, on a discounted basis, in the period in which the liability is incurred. Generally, the fair value of the liability is calculated using discounted cash flow techniques and based on internal estimates and assumptions related to (i) future retirement costs, (ii) future inflation rates and (iii) credit adjusted risk-free interest rates. Significant increases or decreases in the assumptions would result in a significant change to the fair value measurement. Certain assets related to our Offshore Pipelines and Services segment have regulatory obligations to perform remediation, and in some instances dismantlement and removal activities, when the assets are abandoned. These AROs include varying levels of activity including disconnecting inactive assets from active assets, cleaning and purging assets, and in some cases, completely removing the assets and returning the land to its original state. These assets have been in existence for many years and with regular maintenance will continue to be in service for many years to come. It is not possible to predict when demand for these transmission services will cease, however, we do not believe that such demand will cease for the foreseeable future. The majority of the current portion of our AROs, which is included in Accrued expenses and other current liabilities in our Condensed Consolidated Balance Sheets, is related to the retirement of the Midla pipeline. For further discussion related to the retirement of the Midla Pipeline, see the Note 14 - Debt Obligations in the 2017 Form 10-K. The following table presents activity in our asset retirement obligations for the nine months ended September 30, 2018 (in thousands): Current portion $ 6,416 Non-current asset retirement obligation 66,194 Balances at December 31, 2017 72,610 Additions 260 Revision in estimate (216 ) Disposals (516 ) Expenditures (3,149 ) Accretion expense 2,865 Balances at September 30, 2018 71,854 Current portion (3,764 ) Non-current asset retirement obligation $ 68,090 We are required to establish security against potential obligations relating to the abandonment of certain transmission assets that may be imposed on the previous owner by applicable regulatory authorities. We have deposited $5.0 million with a third party to secure our performance on these potential obligations. Those deposits, in our Condensed Consolidated Balance Sheets as of September 30, 2018 and December 31, 2017 , are included in Restricted cash-long term.

Debt Obligations

Debt Obligations	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Debt Obligations	(13) Debt Obligations Our outstanding debt consists of the following (in thousands): September 30, 2018 December 31, 2017 Revolving credit facility $ 600,000 $ 697,900 8.50% Senior unsecured notes, due 2021 425,000 425,000 3.77% Senior secured notes, due 2031 (non-recourse) 57,531 58,324 3.97% Senior secured notes, due 2032 (non-recourse) 30,709 32,025 Other debt — 4,989 Total debt obligations 1,113,240 1,218,238 Unamortized debt issuance costs (8,519 ) (9,231 ) Total debt 1,104,721 1,209,007 Current portion of long-term debt (603,502 ) (7,551 ) Long term debt $ 501,219 $ 1,201,456 AMID Revolving Credit Agreement On June 29, 2018, we amended our revolving credit facility agreement, dated March 8, 2017 (the “Original Credit Agreement”), by entering into the First Amendment to Second Amended and Restated Credit Agreement (the “Amendment” and, the Original Credit Agreement as amended by the Amendment, the “Credit Agreement”; capitalized terms used but not defined herein shall have the meanings assigned thereto in the Credit Agreement) with a syndicate of lenders and Bank of America, N.A., as administrative agent. The Credit Agreement matures on September 5, 2019, and is therefore being presented as a current liability in our Condensed Consolidated Balance Sheet as of September 30, 2018. The Amendment adds a required prepayment in the amount equal to 100% of the net cash proceeds received from the Marine Products and Refined Products asset sales and any other disposition greater than $5 million as defined below. On July 31, 2018, we completed the sale of our Marine Products terminals. Net proceeds from this disposition were approximately $208.6 million , exclusive of $5.7 million in advisory fees and other costs, and were used to pay down the Credit Agreement. The Amendment also amends our borrowing capacity as follows: • upon consummation of the Marine Products sale, the aggregate commitment under the Credit Agreement was automatically reduced by $200.0 million , such that total borrowing capacity under the Credit Agreement is $700.0 million as of September 30, 2018; • upon consummation of the Refined Products sale, the aggregate commitment under the Credit Agreement shall be automatically reduced by 50% of the net cash proceeds of such disposition; and • upon consummation of any disposition greater than $15 million , the aggregate commitment under the Credit Agreement shall be automatically reduced by 25% of the net cash proceeds of such disposition. The Amendment adds a new pricing tier of LIBOR + 3.50% when Consolidated Total Leverage Ratio equals or exceeds 5.0 : 1.0 . The Credit Agreement includes the following financial covenants, as amended by the Amendment and defined in the Credit Agreement, which financial covenants will be tested on a quarterly basis, for the fiscal quarter then ending: Minimum Consolidated Interest Coverage Ratio Maximum Consolidated Total Leverage Ratio Maximum Consolidated Secured Leverage Ratio June 30, 2018 2.50:1.00 6.15:1.00 4.00:1.00 September 30, 2018 2.00:1.00 6.25:1.00 3.75:1.00 December 31, 2018 1.75:1.00 5.50:1.00 3.50:1.00 March 31, 2019 1.75:1.00 5.00:1.00 (1) 3.50:1.00 June 30, 2019 and thereafter 2.00:1.00 5.00:1.00 (1) 3.50:1.00 ___________________________ (1) 5.50 :1.00 during a Specified Acquisition Period As of September 30, 2018 , we were in compliance with our Credit Agreement financial covenants, including those shown below: Ratio Actual Consolidated Interest Coverage Ratio 2.37 Consolidated Total Leverage Ratio 5.65 Consolidated Secured Leverage Ratio 3.31 As of September 30, 2018 , we had $600 million of borrowings, $39.0 million of letters of credit outstanding and $61.0 million of remaining borrowing capacity under the Credit Agreement, of which $41.0 million is currently available. For the nine months ended September 30, 2018 and 2017, the weighted average interest rate, excluding the impact of interest rate swaps, on borrowings under this facility was 6.23% and 4.85% , respectively. Senior Unsecured Notes Our senior unsecured notes include an optional redemption whereby we may elect to redeem the notes, in whole or in part from time-to-time, for a premium. On and after December 15, 2018, we may redeem all or a part of the 8.50% Senior Notes, at the redemption prices set forth below, plus accrued and unpaid interest, if redeemed during the twelve -month period beginning on December 15 of the years indicated below: Year Percentage 2018 104.250% 2019 102.125% 2020 and thereafter 100.000% See Note 14 - Debt Obligations in our 2017 Form 10-K for additional information relating to our outstanding debt. Going Concern Assessment and Management’s Plans Pursuant to FASB ASC 205-40, we are required to assess our ability to continue as a going concern for a period of one year from the date of the issuance of these financial statements. Substantial doubt about an entity’s ability to continue as a going concern exists when relevant conditions and events, considered in the aggregate, indicate that it is probable that the entity will be unable to meet its obligations as they become due within one year from the financial statement issuance date. As discussed above in “ AMID Revolving Credit Agreement ”, our Credit Agreement matures on September 5, 2019 and has not been renewed as of the date of the issuance of these financial statements. As discussed in Note 19 - Related Party Transactions , on September 28, 2018, the Board of Directors of our General Partner received a non-binding proposal from Magnolia, an affiliate of ArcLight to acquire the common units that it does not already own. The transaction is currently in the due diligence phase and requires approval of the Conflicts Committee of the Board of Directors. As a result of this ongoing process, management has deferred finalization of a renewal of the Credit Agreement. While the Partnership intends to renew or extend the terms of its Credit Agreement, until such time as we have executed an agreement to refinance or extend the maturity of our Credit Agreement, we cannot conclude that it is probable we will do so, and accordingly, this raises substantial doubt about our ability to continue as a going concern.

Convertible Preferred Units (No

Convertible Preferred Units (Notes)	9 Months Ended
	Sep. 30, 2018
Partners' Capital [Abstract]
Convertible Preferred Units	(14) Convertible Preferred Units Our convertible preferred units consist of the following (in thousands): Series A Series C Total Units $ Units $ $ December 31, 2017 10,719 $ 191,798 8,965 $ 125,382 $ 317,180 Paid in kind unit distributions 291 — 277 — — September 30, 2018 11,010 $ 191,798 9,242 $ 125,382 $ 317,180 Affiliates of our General Partner hold and participate in quarterly distributions on our convertible preferred units, with such distributions being made in cash, paid-in-kind units or a combination thereof at the election of the Board of Directors of our General Partner (the “Board”). The convertible preferred unitholders have the right to receive cumulative distributions in the same priority and prior to any other distributions made in respect of any other partnership interests. To the extent that any portion of a quarterly distribution on our convertible preferred units to be paid in cash exceeds the amount of cash available for such distribution, the amount of cash available will be paid to our convertible preferred unitholders on a pro rata basis while the difference between the distribution and the available cash will accrue interest until paid. Series A-1 Convertible Preferred Units On April 15, 2013, the Partnership, our General Partner and AIM Midstream Holdings LLC entered into agreements with HPIP, pursuant to which HPIP acquired 90% of our General Partner and all of our subordinated units from AIM Midstream Holdings, LLC and contributed the High Point System, our 574 mile transmission system located in southeast Louisiana and the Gulf of Mexico, and $15.0 million in cash to us in exchange for 5,142,857 of our Series A-1 Units. The holders of Series A-1 Units receive quarterly distributions prior to any distributions to our common unitholders. The quarterly distributions on the Series A-1 Units are equal to the greater of $0.4125 per unit or the declared distribution to common unitholders. The Series A-1 Units may be converted into common units, subject to customary anti-dilutive adjustments, at the option of the unitholders at any time. As of September 30, 2018 , the conversion price was $15.10 and the conversion ratio is 1: 1.1589 . Series A-2 Convertible Preferred Units On March 30, 2015 and June 30, 2015, we entered into two Series A-2 Convertible Preferred Unit Purchase Agreements with Magnolia Infrastructure Partners, an affiliate of HPIP pursuant to which we issued, in separate private placements, newly-designated Series A-2 Units (the “Series A-2 Units”) representing limited partnership interests in the Partnership. As a result, the Partnership issued a total of 2,571,430 Series A-2 Units for approximately $45 million in aggregate proceeds during the year ended December 31, 2015. 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-1 Units (together with the Series A-2 Units, the “Series A Units”), with such distributions being made in cash or with paid-in-kind Series A Units at the election of the Board. On July 27, 2015, we amended our Partnership Agreement to grant us the right (the “Call Right”) to require the holders of the Series A-2 Units to sell, assign and transfer all or a portion of the then-outstanding Series A-2 Units to us for a purchase price of $17.50 per Series A-2 Unit (subject to appropriate adjustment for any equity distribution, subdivision or combination of equity interests in the Partnership). We may exercise the Call Right at any time, in connection with our or our affiliates’ acquisition of assets or equity from ArcLight Energy Partners Fund V, L.P., or one of its affiliates, for a purchase price in excess of $100.0 million . We may not exercise the Call Right with respect to any Series A-2 Units that a holder has elected to convert into common units on or prior to the date we have provided notice of our intent to exercise the Call Right, and we may also not exercise the Call Right if doing so would result in a default under any of our or our affiliates’ financing agreements or obligations. As of September 30, 2018 , the conversion price was $15.10 and the conversion ratio is 1: 1.1589 . Series C Convertible Preferred Units On April 25, 2016, we issued 8,571,429 Series C Units to an ArcLight affiliate in connection with the purchase of membership interests in certain midstream entities. The Series C Units have voting rights that are identical to the voting rights of the common units and will vote with the common units as a single class on an as-converted basis, with each Series C Unit initially entitled to one vote for each common unit into which such Series C Unit is convertible. The Series C Units also have separate class voting rights on any matter, including a merger, consolidation or business combination, that adversely affects, amends or modifies any of the rights, preferences, privileges or terms of the Series C Units. The Series C Units are convertible in whole or in part into common units at any time. The number of common units into which a Series C Unit is convertible will be an amount equal to the sum of $14.00 plus all accrued and accumulated but unpaid distributions, divided by the conversion price. The sale of the Series C Units was exempt from registration under the Securities Act of 1933, as amended (the “Securities Act”) pursuant to Rule 4(a)(2) under the Securities Act. In the event that we issue, sell or grant any common units or convertible securities at an indicative per common unit price that is less than $14.00 per common unit (subject to customary anti-dilution adjustments), then the conversion price will be adjusted according to a formula to provide for an increase in the number of common units into which Series C Units are convertible. As of September 30, 2018 , the conversion price was $13.27 and the conversion ratio is 1 : 1.0550 . In connection with the issuance of the Series C Units, we issued the holders a warrant to purchase up to 800,000 common units at an exercise price of $7.25 per common unit (the “Series C Warrant”). The Series C Warrant is subject to standard anti-dilution adjustments and is exercisable for a period of seven years. The fair value of the Series C Warrant was determined using a market approach that utilized significant inputs which are not observable in the market and thus represent a Level 3 measurement as defined by ASC 820, Fair Value Measurements and Disclosures. The estimated fair value of $4.41 per warrant unit was determined using a Black-Scholes model and the following significant assumptions: (i) a dividend yield of 18% , (ii) common unit volatility of 42% and (iii) the seven -year term of the warrant to arrive at an aggregate fair value of $4.5 million . As conversion is at the option of the holder and redemption is contingent upon a future event, which is outside the control of the Partnership, the Series A-1, A-2 and C Units have been classified as mezzanine equity in the Condensed Consolidated Balance Sheets.

Partners Capital

Partners Capital	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Partners’ Capital	(15) Partners’ Capital Our capital accounts are comprised of 1.3% notional General Partner interests and 98.7% limited partner interests as of September 30, 2018 . 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 interests held by our General Partner. Pursuant to our Partnership Agreement, our General Partner participates in losses and distributions based on its interest. The General Partner’s participation in the allocation of losses and distributions is not limited, and therefore, such participation can result in a deficit to its capital account. As such, allocation of losses and distributions, including distributions for previous transactions between entities under common control, has resulted in a deficit to the General Partner’s capital account included in our Condensed Consolidated Balance Sheets. Outstanding Units The following table presents unit activity (in thousands): General Limited Partner Units Balances at December 31, 2017 965 52,711 LTIP units vesting — 279 Issuance of GP units 16 — Balances at September 30, 2018 981 52,990 General Partner Units In order for our General Partner to maintain its ownership percentage in us, our General Partner paid $0.1 million and $3.9 million for the issuance of 16,326 and 272,811 additional notional General Partner units for the nine months ended September 30, 2018 and 2017, respectively. Distributions Preferred Units Under the Partnership’s agreement of limited partnership, the Partnership is obligated to pay cumulative distributions each quarter on the Series A preferred units (which consists of the Series A-1 and A-2) and Series C preferred units in an amount equal to the greater of $0.4125 , or the distribution declared on the common units. As such, the distributions are accrued at each quarter-end (the “reporting quarter”) based on the subsequent board approval of the distribution method (in the “subsequent quarter”), which may be settled in cash or paid-in-kind (“PIK”) units. To the extent the distribution is to be settled in cash, the distributions are accrued in the reporting quarter and the cash is paid in the subsequent quarter. To the extent the distribution is to be settled in PIK units, the distribution is recognized directly to equity in the reporting quarter. Limited Partner Units (Common Units) The following table reflects distributions declared and paid through September 30, 2018 (in thousands, except per unit data): Date Declared Distribution Payment Date Period for which Distribution Relates General Partner Limited Partner Total Cash Distributions Cash Distributions Per Common Unit July 27, 2018 August 14, 2018 Second Quarter of 2018 $ 72 $ 5,463 $ 5,535 $ 0.1031 April 26, 2018 May 15, 2018 First Quarter of 2018 $ 287 $ 21,853 $ 22,140 $ 0.4125 January 26, 2018 February 14, 2018 Fourth Quarter of 2017 $ 290 $ 21,745 $ 22,035 $ 0.4125 On October 25, 2018 , we announced that the Board of Directors of our general partner declared a quarterly cash distribution of $0.1031 per common unit, which represents the distribution for the third quarter of 2018 and will be paid in the fourth quarter of 2018. See Note 22 - Subsequent Events for more information. The following table details cash distributions paid or accrued as of, and for, the three and nine months ended September 30, 2018 (in thousands): Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 Series A Units Cash paid $ 4,542 $ 2,145 $ 9,084 $ 6,790 Accrued (1) 4,542 4,105 4,542 4,105 Paid-in-kind units — 1,924 3,767 6,838 Series C Units Cash paid $ 3,812 $ 3,627 $ 7,624 $ 10,880 Accrued (1) 3,812 4,150 3,812 4,150 Paid-in-kind units — — 4,309 — Series D Units Cash paid $ — $ 963 $ — $ 2,888 Limited Partners’ Units (2) Cash paid $ 5,463 $ 21,345 $ 49,061 $ 67,648 General Partner’s Units (3) Cash paid $ 72 $ 277 $ 649 $ 645 Summary Cash paid $ 13,889 $ 28,357 $ 66,418 $ 88,851 Accrued (1) 8,354 8,255 8,354 8,255 Paid-in-kind units — 1,924 8,076 6,838 __________________________ (1) Can be paid in either Cash, PIK or a combination of both. PIK payments on the Series C Units require consent of the holder. (2) Limited Partner distributions do not include $5.5 million and $21.7 million of distributions declared in the fourth quarter which relate to the third quarter of 2018 and 2017, respectively. (3) General Partner distributions do not include $0.1 million and $0.3 million of distributions declared in the fourth quarter which relate to the third quarter of 2018 and 2017, respectively. Fair Value Determination of PIK of Preferred Units The fair value of the PIK distributions was determined using the market and income approaches, requiring significant inputs that are not observable in the market and thus represent a Level 3 measurement. Under the income approach, the fair value estimates for all periods presented were based on (i) present value of estimated future contracted distributions, (ii) option values ranging from $0.31 per unit to $2.05 per unit using a Black-Scholes model, (iii) assumed discount rates ranging from 5.80% to 6.23% , and (iv) assumed growth rates of 1.0% .

Net Income (Loss) per Limited P

Net Income (Loss) per Limited Partner Unit	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Net Income (Loss) per Limited Partner Unit	(16) Net Income (Loss) per Limited Partner Unit As discussed in Note 4 - Acquisitions and Dispositions , the JPE Merger on March 8, 2017 was a combination between entities under common control. As a result, prior periods were retrospectively adjusted to furnish comparative information. Accordingly, the prior period earnings combining both entities were allocated among our General Partner and common unitholders assuming JPE units were converted into our common units in the comparative historical periods. The calculation of basic and diluted limited partners' net income (loss) per common unit is summarized below (in thousands, except per unit amounts): Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 Income (loss) from continuing operations $ 38,183 $ 11,806 $ 7,067 $ (42,266 ) Net income attributable to noncontrolling interests (25 ) (621 ) (83 ) (3,386 ) Net income (loss) from continuing operations attributable to the Partnership 38,158 11,185 6,984 (45,652 ) Distributions on Series A Units (4,542 ) (4,105 ) (13,626 ) (12,472 ) Distributions on Series C Units (3,812 ) (4,150 ) (11,437 ) (11,403 ) Distributions on Series D Units — — — (1,925 ) General Partner's distribution (73 ) (287 ) (434 ) (763 ) General Partner's share in undistributed (loss) income (303 ) 210 683 1,729 Income (loss) from continuing operations attributable to Limited Partners 29,428 2,853 (17,830 ) (70,486 ) Income from discontinued operations, net of tax — 44,696 — 42,185 Net income (loss) attributable to Limited Partners $ 29,428 $ 47,549 $ (17,830 ) $ (28,301 ) Weighted average number of common units outstanding: Basic 52,984 52,021 52,917 52,021 Potentially dilutive common unit equivalents (1) 22,541 — — — Diluted 75,525 52,021 52,917 52,021 Limited Partners' net income (loss) per common unit - Basic and Diluted Basic: Income (loss) from continuing operations $ 0.56 $ 0.05 $ (0.34 ) $ (1.35 ) Income (loss) from discontinued operations — 0.86 — 0.81 Net income (loss) $ 0.56 $ 0.91 $ (0.34 ) $ (0.54 ) Diluted: Income (loss) from continuing operations $ 0.39 $ 0.05 $ (0.34 ) $ (1.35 ) Income (loss) from discontinued operations — 0.86 — 0.81 Net income (loss) $ 0.39 $ 0.91 $ (0.34 ) $ (0.54 ) _____________________________________ (1) Potential common unit equivalents were antidilutive for the three months ended September 30, 2017 and for the nine months ended September 30, 2018 and 2017. As a result, 24.9 million potential common unit equivalents for the three months ended September 30, 2017 and 23.4 million potential common unit equivalents and 24.8 million potential common unit equivalents for the nine months ended September 30, 2018 and 2017, respectively, have been excluded from the determination of diluted limited partners' net income (loss) per common unit.

Incentive Compensation

Incentive Compensation	9 Months Ended
	Sep. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Incentive Compensation	(17) Incentive Compensation All equity-based awards issued under the long-term incentive plan (“LTIP”) consist of either restricted (“RSUs”) or performance-based (“PSUs”) phantom units, or option grants. Future awards may be granted at the discretion of the Compensation Committee of the Board and subject to approval by the Board. As of September 30, 2018 , there were 3,763,750 common units available for future grants under the LTIP. The following table presents the components of equity-based compensation expense for the three and nine months ended September 30, 2018 and 2017 (in thousands): Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 Grant Type: RSU $ 1,083 $ 815 $ 2,616 $ 6,010 PSU 237 — 867 — Options 15 19 46 57 Total $ 1,335 $ 834 $ 3,529 $ 6,067 During the nine months ended September 30, 2018 , we granted 818,357 RSU’s at a weighted-average fair value per unit of $8.54 , vested 351,166 RSU’s at a weighted-average fair value per unit of $6.26 and forfeited 356,479 RSU’s at a weighted-average fair value per unit of $6.62 . Unrecognized compensation expense related to RSU’s was $8.6 million at September 30, 2018 . During the nine months ended September 30, 2018 , we did not grant any options or performance-based awards under our LTIP. Unrecognized compensation expense related to options and performance-based awards was $0.1 million and $4.9 million , respectively, at September 30, 2018 . Defined Contribution Plan For the three and nine months ended September 30, 2018 and 2017 , compensation expense associated with our 401(k)-defined contribution plan’s employer matching was $0.6 million and $0.5 million , respectively, and $1.8 million and $1.4 million , respectively. There was no change to the defined contribution plan. Cash Retention Plan On September 2, 2018, the Partnership implemented a long-term cash retention award for all employees holding RSU’s under the Partnership’s LTIP. At each future vesting date of time-based unvested phantom units outstanding on July 28, a cash award in the amount of $6.00 per phantom unit will also be earned. Holders of PSU’s were not included in the cash retention award. The expense associated with this award will be recognized over the service period. During the three months ended September 30, 2018, approximately $0.9 million related to this plan was included in Corporate expenses in the Condensed Consolidated Statements of Operations.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	(18) 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 certainty, our management believes that the resolution of any of our pending proceedings 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 in our 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.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2018
Related Party Transactions [Abstract]
Related Party Transactions	(19) Related Party Transactions To the extent applicable, our discussion below includes the nature of our relationship and activities that we had with our related parties, as defined by ASC 850, Related Party Disclosures , for the nine months ended September 30, 2018 and 2017 and the outstanding balances as of September 30, 2018 and December 31, 2017 . Balances associated with our investments in unconsolidated affiliates are disclosed in Note 10 - Investments in unconsolidated affiliates. Blackwater Midstream Holdings, LLC In December 2013, we acquired Blackwater Midstream Holdings, LLC (“Blackwater”) from an affiliate of ArcLight. The acquisition agreement included a provision whereby an ArcLight affiliate would be entitled to an additional $5.0 million of merger consideration based on Blackwater meeting certain operating targets. At September 30, 2018 , we have $5.0 million accrued to the ArcLight affiliate which is included in Accrued expense and other current liabilities in the accompanying Condensed Consolidated Balance Sheets. Final resolution of the merger consideration will be determined in the fourth quarter of 2018 in connection with the sale of Marine Products. Republic Midstream, LLC Republic Midstream, LLC (“Republic”), is an entity owned by ArcLight to which we historically charged a monthly fee of approximately $0.1 million . The services agreement with Republic terminated according to its terms in September 2017 and services are no longer provided to Republic. As of December 31, 2017 , we had an accounts receivable balance due from Republic of $0.8 million which is included in Other current assets in the accompanying Condensed Consolidated Balance Sheets. Magnolia Infrastructure Holdings, LLC On September 28, 2018, the Board of Directors of our General Partner received a non-binding proposal from Magnolia, pursuant to which Magnolia would acquire all common units of the Partnership that Magnolia and its affiliates do not already own in exchange for $6.10 per common unit. If approved, it is currently expected that the transaction would be effected through a merger of the Partnership with a subsidiary of ArcLight. The transaction, as proposed, is subject to a number of contingencies, including Magnolia's completion of due diligence, the approval of the Conflicts Committee, the approval by holders of a majority of the outstanding common units of the Partnership and the satisfaction of any conditions to the consummation of a transaction set forth in any definitive agreement concerning the transaction. There can be no assurance that definitive agreement will be executed or that any transaction will materialize. General Partner During the nine months ended September 30, 2018 , our General Partner paid $31.8 million related to Corporate overhead support which was presented as part of the contribution line item in Cash flows from financing activities in our Condensed Consolidated Statements of Cash Flows. As of September 30, 2018 , and December 31, 2017 , we had $7.9 million and $6.5 million , respectively, of accounts payable due to our General Partner, which has been recorded in Accrued expenses and other current liabilities and relates primarily to compensation. This payable/receivable is generally settled on a quarterly basis related to the foregoing transactions. On March 11, 2018, the Partnership and Magnolia entered into a Capital Contribution Agreement (the “Capital Contribution Agreement”) to provide additional capital and overhead support to us during the first three quarters of 2018 in connection with temporary curtailment of production flows at Delta House. Pursuant to the Capital Contribution Agreement, Magnolia has agreed to provide quarterly capital contributions, in an amount to be agreed, up to the difference between the actual cash distribution received by us on account of our interest in Delta House and the quarterly cash distribution expected to be received had the production flows to Delta House not been curtailed. In accordance with this agreement, Magnolia paid a capital contribution of $9.4 million in the second quarter of 2018. Subsequent to June 30, 2018, in accordance with this agreement, Magnolia paid a capital contribution of $8.3 million in August 2018. Both of these capital contributions are included in the $31.8 million related to Corporate overhead support discussed above. Destin and Okeanos On November 1, 2016, we became operator of the Destin and Okeanos pipelines and entered into operating and administrative management agreements under which our affiliates pay a monthly fee for general and administrative services provided by us. In addition, the affiliates reimburse us for certain transition related expenses. For the nine months ended September 30, 2018 , and 2017 , we recognized $1.9 million of management fee income for each respective period. For Destin, we had an outstanding accounts payable balance of $0.6 million as of September 30, 2018 , which is included in Accrued expenses and other current liabilities and an outstanding accounts receivable balance of $0.5 million as of December 31, 2017 , which is included in Other current assets in the accompanying Condensed Consolidated Balance Sheets. For Okeanos, we had an outstanding accounts receivable balance of $0.1 million and $0.4 million as of September 30, 2018 and December 31, 2017 , respectively, which is included in Other current assets in the accompanying Condensed Consolidated Balance Sheets. Consolidated Asset Management Services, LLC ("CAMS") Dan Revers, a director of our General Partner, indirectly owns in excess of 10% of CAMS, which, through various subsidiaries or affiliates, provides pipeline integrity services to the Partnership and subleases an office space from the Partnership. During the nine months ended September 30, 2018 and 2017 , the Partnership was invoiced by CAMS $0.2 million for each respective period and had no outstanding accounts receivable balance as of September 30, 2018 or December 31, 2017 . Other Related Party Transactions Michael D. Rupe, the brother of Ryan Rupe (the Partnership’s Vice President - Natural Gas Services and Offshore Pipelines), is the Chief Financial Officer of CIMA Energy Ltd., a crude oil and natural gas marketing company (“CIMA”). The Partnership regularly engages in purchases and sales of crude oil and natural gas with CIMA. During the nine months ended September 30, 2018 , the Partnership invoiced CIMA $1.7 million and received invoicing from CIMA of $3.5 million in connection with such transactions. For the nine months ended September 30, 2017 , the Partnership invoiced CIMA $6.2 million and received invoices from CIMA of $3.7 million for services. As of September 30, 2018 , and December 31, 2017 , the Partnership had minimal outstanding amounts due from CIMA. During September and October 2017, under a transition services agreement, the Partnership made payments on behalf of AMID Merger GP II, LLC related to the Propane Business sale. As of September 30, 2018 , and December 31, 2017 , we had an outstanding accounts receivable balance related to these payments of $1.1 million and $2.5 million , respectively, which is included in Other current assets in the accompanying Condensed Consolidated Balance Sheets. For additional information on Related Parties, see Note 21 - Related Party Transactions , in our 2017 Form 10-K.

Supplemental Cash Flow Informat

Supplemental Cash Flow Information (Notes)	9 Months Ended
	Sep. 30, 2018
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	(20) Supplemental Cash Flow Information Supplemental cash flows and non-cash transactions consist of the following (in thousands): Nine months ended September 30, 2018 2017 Supplemental cash flow information Cash paid for interest $ 49,294 $ 40,885 Supplemental non-cash information Investing Increase (decrease) in accrued property, plant and equipment purchases (1,652 ) (15,112 ) Accrued contributions to unconsolidated affiliates (89 ) — Financing Issuance of common units for the Panther acquisition — 12,532 Contributions from an affiliate holding limited partner interests — 4,000 Accrued distributions on convertible preferred units 8,354 8,255 Paid-in-kind distributions on convertible preferred units 8,076 6,838

Reportable Segments

Reportable Segments	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Reportable Segments	(21) Reportable Segments Our operations are organized into five reportable segments: (1) Gas Gathering and Processing Services, (2) Liquid Pipelines and Services, (3) Natural Gas Transportation Services, (4) Offshore Pipelines and Services and (5) Terminalling Services. We disclose the results of each of our operating segments in accordance with ASC 280, Segment Reporting (“ASC 280”) . Each of our operating segments is managed by a senior executive reporting directly to our Chief Executive Officer, the chief operating decision maker (“CODM”). Our Chief Executive Officer evaluates the performance of our reportable segments primarily on the basis of segment gross margin, which is our segment measure of profitability. Our CODM uses gross margin as the primary measure for reviewing our segments’ profitability and therefore, in accordance with ASC 280, we have presented gross margin for each segment. For segments other than Terminalling Services, we define segment gross margin as total revenue plus unconsolidated affiliate earnings less unrealized gains (losses) on commodity derivatives, construction and operating management agreement income and the cost of sales. Gross margin for Terminalling Services also deducts direct operating expense, which includes direct labor, general materials and supplies and direct overhead. The following tables set forth our segment information for the three and nine months ended September 30, 2018 and 2017 (in thousands): Three months ended September 30, 2018 Gas Gathering and Processing Services Liquid Pipelines and Services Natural Gas Transportation Services Offshore Pipelines and Services Terminalling Services Total Revenue $ 53,429 $ 109,559 $ 12,710 $ 19,331 $ 7,551 $ 202,580 Loss on commodity derivatives, net (93 ) (141 ) — — — (234 ) Total revenue 53,336 109,418 12,710 19,331 7,551 202,346 Operating expenses: Cost of sales 37,917 103,345 5,502 1,959 1,551 150,274 Direct operating expenses — — — — 2,152 20,407 Corporate expenses 23,857 Termination fee 17,000 Depreciation, amortization and accretion expense 23,040 Gain on sale of assets, net (99,396 ) Total operating expenses 135,182 Operating income 67,164 Other income (expense), net Interest expense, net of capitalized interest (22,267 ) Other expense, net (128 ) Earnings in unconsolidated affiliates — 3,172 — 21,450 — 24,622 Income from continuing operations before income taxes 69,391 Income tax expense (31,208 ) Income from continuing operations 38,183 Net income attributable to non-controlling interests (25 ) Net income attributable to the Partnership $ 38,158 Segment gross margin $ 15,421 $ 9,351 $ 7,044 $ 38,823 $ 3,848 Three months ended September 30, 2017 Gas Gathering and Processing Services Liquid Pipelines and Services Natural Gas Transportation Services Offshore Pipelines and Services Terminalling Services Total Revenue $ 37,287 $ 87,022 $ 11,131 $ 14,360 $ 13,087 $ 162,887 Loss on commodity derivatives, net (65 ) (532 ) — — — (597 ) Total revenue 37,222 86,490 11,131 14,360 13,087 162,290 Operating expenses: Cost of sales 24,492 80,510 5,692 558 1,146 112,398 Direct operating expenses 3,432 20,705 Corporate expenses 27,083 Depreciation, amortization and accretion expense 26,781 Gain on sale of assets, net (4,061 ) Total operating expenses 182,906 Operating loss (20,616 ) Other income (expenses), net Interest expense, net of capitalized interest (17,759 ) Other income, net 34,085 Earnings in unconsolidated affiliates — 1,317 — 15,510 — 16,827 Income from continuing operations before income taxes 12,537 Income tax expense (731 ) Income from continuing operations 11,806 Income from discontinued operations, including gain on disposition 44,696 Net income 56,502 Net income attributable to non-controlling interests (621 ) Net income attributable to the Partnership $ 55,881 Segment gross margin $ 12,761 $ 7,808 $ 5,356 $ 29,312 $ 8,509 Nine months ended September 30, 2018 Gas Gathering and Processing Services Liquid Pipelines and Services Natural Gas Transportation Services Offshore Pipelines and Services Terminalling Services Total Revenue $ 138,613 $ 349,947 $ 44,339 $ 54,711 $ 41,310 $ 628,920 Loss on commodity derivatives, net (385 ) (145 ) — — — (530 ) Total revenue 138,228 349,802 44,339 54,711 41,310 628,390 Operating expenses: Cost of sales 95,921 333,342 16,628 6,105 9,952 461,948 Direct operating expenses — — — — 10,605 65,595 Corporate expenses 69,922 Termination fee 17,000 Depreciation, amortization and accretion expense 66,274 Gain on sale of assets, net (99,491 ) Total operating expenses 581,248 Operating income 47,142 Other income (expense), net Interest expense, net of capitalized interest (55,834 ) Other income, net 62 Earnings in unconsolidated affiliates — 7,878 — 39,864 — 47,742 Income from continuing operations before income taxes 39,112 Income tax expense (32,045 ) Net income 7,067 Net income attributable to non-controlling interests (83 ) Net income attributable to the Partnership $ 6,984 Segment gross margin $ 42,613 $ 24,365 $ 27,384 $ 88,470 $ 20,753 Nine months ended September 30, 2017 Gas Gathering and Processing Services Liquid Pipelines and Services Natural Gas Transportation Services Offshore Pipelines and Services Terminalling Services Total Revenue $ 111,001 $ 253,590 $ 34,966 $ 41,330 $ 47,544 $ 488,431 (Loss) gain on commodity derivatives, net (170 ) 137 — — — (33 ) Total revenue 110,831 253,727 34,966 41,330 47,544 488,398 Operating expenses: Cost of sales 74,261 236,896 17,630 6,487 7,612 342,886 Direct operating expenses — — — — 9,503 56,819 Corporate expenses 84,570 Depreciation, amortization and accretion expense 78,834 Gain on sale of assets, net (4,064 ) Total operating expenses 559,045 Operating loss (70,647 ) Other income (expenses), net Interest expense, net of capitalized interest (51,037 ) Other income, net 32,248 Earnings in unconsolidated affiliates — 3,886 — 45,895 — 49,781 Loss from continuing operations before income taxes (39,655 ) Income tax expense (2,611 ) Loss from continuing operations (42,266 ) Income from discontinued operations, including gain on disposition 42,185 Net loss (81 ) Net income attributable to non-controlling interests (3,386 ) Net loss attributable to the Partnership $ (3,467 ) Segment gross margin $ 36,663 $ 21,209 $ 17,106 $ 80,738 $ 30,429 A reconciliation of total assets by segment to the amounts included in the Condensed Consolidated Balance Sheets follows (in thousands): September 30, December 31, 2018 2017 Segment assets: Gas Gathering and Processing Services $ 397,726 $ 404,872 Liquid Pipelines and Services 370,833 359,646 Natural Gas Transportation Services 267,185 268,991 Offshore Pipelines and Services 525,493 553,213 Terminalling Services 187,779 293,085 Other (1) 85,589 43,659 Total assets $ 1,834,605 $ 1,923,466 Investment in unconsolidated affiliates: Liquid Pipelines and Services $ 68,849 $ 64,399 Offshore Pipelines and Services 267,940 284,035 Total investment in unconsolidated affiliates $ 336,789 $ 348,434 ________________________ (1) Other assets consists primarily of corporate assets not allocable to segments, such as leasehold improvements and other current assets. The following table sets forth capital expenditures for the three and nine months ended September 30, 2018 and 2017 by segment (in thousands): Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 Capital expenditures Gas Gathering and Processing Services $ 11,603 $ 4,788 $ 24,914 $ 13,315 Liquid Pipelines and Services 1,468 1,301 12,649 2,677 Natural Gas Transportation Services 1,554 6,431 4,045 30,797 Offshore Pipelines and Services 155 2,283 20,491 3,417 Terminalling Services 691 3,954 6,813 6,795 Corporate 1,358 1,235 4,430 4,882 Total capital expenditures (1) $ 16,829 $ 19,992 $ 73,342 $ 61,883 _____________________________________ (1) Capital expenditures exclude expenditures made for the Propane Business of $0.7 million and $ 3.1 million for the three and nine months ended September 30, 2017 , respectively, as the business was sold in 2017.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2018
Subsequent Events [Abstract]
Subsequent Events	(22) Subsequent Events Distribution On October 25, 2018 , we announced that the Board of Directors of our General Partner declared a quarterly cash distribution of $0.1031 per common unit, or $0.4125 per common unit annualized, with respect to the third quarter of 2018, which is consistent with our second quarter of 2018 per common unit distribution. The distribution will be paid on November 14, 2018 to unitholders of record as of the close of business on November 6, 2018 . Ajax Settlement American Midstream Permian, LLC and Ajax Resources, LLC (“Ajax”) are parties to a Gas Processing and Gathering Agreement, dated October 1, 2013, pursuant to which American Midstream Permian, LLC’s Yellow Rose System gathers and processes Ajax’s production from its dedicated acreage in the Permian Basin. On June 13, 2016, the Partnership filed a Petition, Application for Temporary Restraining Order and Temporary Injunction in District Court for Harris County, Texas seeking to enjoin Ajax from terminating the Agreement. On December 13, 2017, Ajax sent the Partnership a notice stating that following an audit conducted pursuant to the Agreement, it concluded that the Partnership underpaid Ajax during the period between January 2015 and May 2017, and Ajax requested that the Partnership pay for the alleged damages. On September 25, 2018, Ajax filed an answer and counterclaim to the Partnership’s Petition asserting that the Partnership breached the Agreement with Ajax and seeking damages in the amount of $4.7 million plus attorneys’ fees. On October 23, 2018, the parties agreed to settle this matter, and the Partnership made a $2.0 million payment to Ajax in exchange for Ajax’s release of all claims against the Partnership. On October 26, 2018, the parties filed a Joint Motion for Dismissal with Prejudice with the court. The Partnership accrued an amount equal to $2.0 million for this matter in the third quarter of 2018.

Organization and Basis of Pre_2

Organization and Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	Organization American Midstream Partners, LP (together with its consolidated subsidiaries, the “Partnership,” “we,” “us” or “our”) is a growth-oriented Delaware limited partnership that was formed in August 2009 to own, operate, develop and acquire a diversified portfolio of midstream energy assets. The Partnership’s general partner, American Midstream GP, LLC (the “General Partner”), is 77% directly owned by High Point Infrastructure Partners, LLC (“HPIP”) and 23% indirectly owned by Magnolia Infrastructure Holdings, LLC (“Magnolia”), both of which are affiliates of ArcLight Capital Partners, LLC (“ArcLight”). Our capital accounts consist of notional General Partner units and units representing limited partner interests. We provide critical midstream infrastructure that links producers of natural gas, crude oil, NGLs, condensate and specialty chemicals to numerous intermediate and end-use markets. Through our five reportable segments, (1) Gas Gathering and Processing Services, (2) Liquid Pipelines and Services, (3) Natural Gas Transportation Services, (4) Offshore Pipelines and Services and (5) Terminalling Services, we engage in the business of gathering, treating, processing and transporting natural gas; gathering, transporting, storing, treating and fractionating NGLs; gathering, storing and transporting crude oil and condensates; and storing refined products. Most of our cash flow is generated from fee-based and fixed-margin compensation for gathering, processing, transporting and treating natural gas and crude oil; firm capacity reservation charges; interruptible transportation charges; guaranteed firm storage contracts; throughput fees and other optional charges associated with ancillary services.
Basis of Presentation	Basis of presentation The accompanying Condensed Consolidated Financial Statements are unaudited and have been prepared in accordance with Article 10 of Regulation S-X for interim financial information. Accordingly, they do not include all the information and notes required by GAAP for complete financial statements. In the opinion of our management, all adjustments, consisting only of normal recurring adjustments, considered necessary for a fair statement have been included. The results of operations for interim periods are not necessarily indicative of results of operations for a full year. These 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, 2017 filed with the U.S. Securities and Exchange Commission (the “SEC”) on April 9, 2018 (the “2017 Form 10-K”). On April 15, 2013, ArcLight affiliates obtained control of our General Partner. We account for transactions between entities under common control at the affiliate's historical costs. For those transactions, our historical financial statements will be revised to include the results attributable to the assets acquired as if they were acquired on April 15, 2013 or the date the ArcLight affiliates obtained control of the assets or business acquired.
New Accounting Pronouncements	Standards Adopted in 2018 Revenue from Contracts with Customers (Topic 606 ) - In May 2014, the Financial Accounting Standards Board (the “FASB”) issued a new standard related to revenue recognition which supersedes most of the existing revenue recognition requirements in GAAP and requires entities to recognize revenue at an amount that reflects the consideration to which an entity expects to be entitled in exchange for transferring goods or services to a customer. It also requires significantly expanded disclosures regarding the qualitative and quantitative information of an entity’s nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. The FASB has issued several amendments to the standard, including clarification on accounting for licenses of intellectual property, identifying performance obligations, reporting gross versus net revenue and narrow-scope revisions, and practical expedients. We adopted the new standard on January 1, 2018 (the “initial application” date): • using the modified retrospective application, with no restatement of the comparative periods presented and a cumulative effect adjustment to retained earnings as of the date of adoption, and • disclosing the impact of the new standard in our Condensed Consolidated Financial Statements included in this report. Our revenue is derived from the provision of gathering, processing, transportation, terminalling and storage services and the sale of commodities primarily to marketers and brokers, refiners and chemical manufacturers, utilities and power generation customers, industrial users and local distribution companies. Beginning on January 1, 2018, we account for revenue from contracts with customers in accordance with Topic 606. The unit of account in Topic 606 is a performance obligation, which is a promise in a contract to transfer to a customer either a distinct good or service (or bundle of goods or services) or a series of distinct goods or services provided at a point in time or over a period of time. Topic 606 requires that a contract’s transaction price, which is the amount of consideration to which an entity expects to be entitled in exchange for transferring promised goods or services to a customer, is to be allocated to each performance obligation in the contract based on relative standalone selling prices and recognized as revenue when (point in time) or as (over time) the performance obligation is satisfied. Commodity Sales - For the majority of our commodity sales contracts: (i) each unit of product is a separate performance obligation, since our promise is to sell multiple distinct units of product at a point in time, (ii) the transaction price principally consists of variable consideration, which is determinable on commodity index prices for the volume of the product sold to the customer that month and (iii) the transaction price is allocated to each performance obligation based on the product’s standalone selling price. Revenues from sales of commodities are recognized at the point in time when control of the commodity transfers to the customer, which generally occurs upon delivery of the product to the customer or its designee. Payment is generally received from the customer in the month following delivery. Contracts with customers have varying terms, including spot sales, month-to-month contracts and multi-year agreements. In our Liquid Pipelines and Services segment, we enter into purchase and sales contracts as well as buy/sell contracts with counterparties, under which we gather and transport different types of crude oil and eventually sell the crude oil to either the same counterparty or different counterparties. For each of these arrangements, the Partnership assesses if control of the underlying commodity volumes transfer to the Partnership. Generally, the Partnership is unable to direct the use of the commodity volumes it purchases from the supplier because the Partnership is contractually required to redeliver an equivalent volume of the commodity back to the supplier or to a specified customer, therefore these arrangements are recorded on a net basis. Occasionally, we enter into crude oil inventory exchange arrangements with the same counterparty where the purchase and sale of inventory are considered in contemplation of each other. These types of arrangements are accounted for as inventory exchanges and are recorded on a net basis. Services - The Partnership provides gathering, processing, transportation, terminalling and storage services pursuant to a variety of contracts. Generally, for the majority of these contracts: (i) our promise is to transfer (or stand ready to transfer) a series of distinct integrated services over a period of time, which is a single performance obligation and (ii) the transaction price includes fixed or variable consideration, or both fixed and variable consideration. The amount of consideration is determinable at contract inception or at each month’s end based on our right to invoice at month end for the value of services provided to the customer in that month. Revenue is recognized over the service period specified in the contract as the services are rendered using a time-based (passage of time) or units-based (units of service transferred) method for measuring provision of the services. Progress towards satisfying our performance obligation is based on the firm or interruptible nature of the promised service and the terms and conditions of the contract (such as contracts with or without makeup rights). Payment is generally received from the customer in the month of service or the month following the service. Contracts with customers generally are a combination of month-to-month and multi-year agreements. Firm Services - Firm services are services that are promised to be available to the customer at all times during the term of the contract with limited exceptions. These agreements require customers to deliver, transport or throughput a minimum volume over an agreed upon period. Substantially all of such agreements are entered into with customers to economically support the return on our capital expenditure necessary to construct the related asset. Our firm service contracts are typically structured with take-or-pay or minimum volume provisions, which specify minimum service quantities a customer will pay for even if it chooses not to receive or use them in the specified service period (referred to as “deficiency quantities”). Under firm service contracts, we record a receivable from the customer in the period that services are provided or when the transaction occurs, including amounts for deficiency quantities from customers associated with minimum volume commitments. If a customer has a make-up right associated with a deficiency, we defer the revenue attributable to the counterparty’s make-up right and subsequently recognize the revenue at the earlier of when the deficiency volume is delivered or shipped, when the make-up right expires or when it is determined that the customer’s ability to utilize the make-up right is remote. Interruptible Services - Interruptible services are services provided to the extent that we have available capacity. Generally, we do not have an obligation to perform these services until we accept a customer’s periodic request for service. For the majority of these contracts, the customer will pay only for the actual quantities of services it chooses to receive or use, and we typically recognize the transaction price as revenue as those units of service are transferred to the customer in the specified service period. Gathering and Processing - Our Gas Gathering and Processing Services segment provides “wellhead-to-market” services to producers of natural gas and natural gas liquids, which include transporting raw natural gas from various receipt points 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. Services can be firm if subject to a minimum volume commitment or acreage dedication or interruptible when offered on an as requested, non-guaranteed basis. Revenue for fee-based gathering and processing services are valued based on the rate in effect for the month of service and is recognized in the month of service based on the volumes of natural gas we gather, process and fractionate. Under these arrangements, we may take control of: (i) none of the commodities we sell (i.e., residue gas or NGLs), (ii) a portion of the commodities we sell or (iii) all of the commodities we sell. In those instances where we purchase and obtain control of the entire natural gas stream in our producer arrangements, we have determined these are contracts with suppliers rather than contracts with customers and therefore, these arrangements are not included in the scope of Topic 606. These supplier arrangements are subject to updated guidance in Accounting Standards Codification (“ASC”) 705, Cost of Sales and Services , whereby any embedded fees within such contracts, which historically have been reported as services revenue, are now reported as a reduction to cost of sales upon adoption of Topic 606. In those instances where we remit all of the cash proceeds received from third parties for selling the extracted commodities to the producer, less the fees attributable to these arrangements, we have determined that the producer has control over these commodities. Upon adoption of Topic 606, we eliminated recording both sales revenue (natural gas and products) and cost of sales amounts and now only record fees attributable to these arrangements as service revenues. In other instances where we do not obtain control of the extracted commodities we sell, we are acting as an agent for the producer and, upon adoption of Topic 606, we have continued to recognize services revenue for the net amount of consideration we retain in exchange for our service. The Partnership may charge additional service fees to customers for a portion of the contract term (i.e., for the first year of a contract or until reaching a volume threshold) due to the significant upfront capital investment, and these fees are initially deferred and recognized to revenue over the expected period of customer benefit, generally the lesser of the expected contract term or the life of the related properties. Transportation - Our transportation operations generally consist of fee-based activities associated with transporting crude oil, natural gas and NGL on pipelines, gathering systems and trucks. Revenues from pipeline tariffs and fees are associated with the transportation at a published tariff, as well as revenues associated with agreements for committed capacity on various assets. We primarily recognize pipeline tariff and fee revenues over time based on the volumes delivered and invoiced. The majority of our pipeline tariff and fee revenues are based on actual volumes and rates. As is common in the pipeline transportation industry, our tariffs incorporate a loss allowance factor. The intent of the allowance in arrangements for the transportation of natural gas is to approximate the natural shrink that occurs when transporting the gas. For crude oil transportation arrangements, loss allowance provisions are immaterial to the Partnership. In the event the Partnership retains excess natural gas and crude oil and subsequently sells the commodity to a third party, the sale is recorded at that point in time as a commodity sale. Terminalling and Storage - In our Terminalling Services segment, we generally receive fee-based compensation on guaranteed firm storage contracts, throughput fees charged to our customers when their products are either received or disbursed, and other operational charges associated with ancillary services provided to our customers, such as excess throughput and steam heating. Storage fees resulting from short-term and long-term contracts are typically recognized in revenue ratably over the term of the contract regardless of the actual storage capacity utilized. Adoption of the new revenue standard resulted in changes to the timing of revenue recognition and in the reclassification between financial statement line items. See Note 3 - Revenue Recognition , for further discussion . Statement of Cash Flows - In August 2016, the FASB issued Accounting Standards Update (“ASU”) No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (“ASU 2016-15”). ASU 2016-15 provides specific guidance on cash flow classification issues to reduce diversity in practice. In connection with the January 1, 2018 retrospective adoption of this ASU, for the nine months ended September 30, 2017, we reclassified $9.4 million in distributions received from unconsolidated affiliates from operating cash inflows to investing cash inflows and reclassified $2.5 million of transaction costs associated the disposal of our Propane Business from an investing cash outflow to an operating cash outflow in our Condensed Consolidated Statements of Cash Flows. In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash (“ASU 2016-18”), which requires amounts described as restricted cash and restricted cash equivalents to be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. A reconciliation between the balance sheet and the statement of cash flows must be disclosed when the balance sheet includes more than one line item for cash, cash equivalents, restricted cash and restricted cash equivalents. We retrospectively adopted ASU 2016-18 as of January 1, 2018. For the nine months ended September 30, 2017, cash flows from operating activities have been adjusted to remove the impact of $3.5 million in restricted cash outflows, and cash flows from investing activities has been adjusted to remove the impact of $302.7 million in restricted cash inflows. During the preparation of our third quarter of 2018 Condensed Consolidated Financial Statements, we identified an error in the presentation of distributions from unconsolidated affiliates in our Condensed Consolidated Statements of Cash Flows in our March 31, 2018 and June 30, 2018 Quarterly Reports on Form 10-Q. This error resulted in the overstatement of net cash provided by operating activities and a corresponding overstatement of net cash used in investing activities of $2.5 million for the three months ended March 31, 2018 and the understatement of net cash provided by operating activities and a corresponding understatement of net cash used in investing activities of $1.0 million for the six months ended June 30, 2018. This error also resulted in a $6.3 million overstatement of net cash provided by operating activities and a corresponding overstatement of net cash used in investing activities for the six months ended June 30, 2017 as presented in the June 30, 2018 Quarterly Report on Form 10-Q. These errors were corrected in the accompanying Condensed Consolidated Statements of Cash Flows for the nine months ended September 30, 2018 and 2017. The errors were not considered material to the previously issued or current financial statements. Stock Compensation - In May 2017, the FASB issued ASU No. 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting (“ASU 2017-09”). ASU 2017-09 was issued with the intent to clarify the scope of modification accounting and when it should be applied to a change to the terms or conditions of a share-based payment award. Under the new guidance, modification accounting is required for all changes to share based payment awards, unless all the following conditions are met: (i) there is no change to the fair value of the award, (ii) the vesting conditions have not changed and (iii) the classification of the award as an equity instrument or a debt instrument has not changed. We adopted ASU 2017-09 on its effective date of January 1, 2018, and the adoption did not have a material impact on our Condensed Consolidated Financial Statements. Income Taxes - In March 2018, the FASB issued ASU No. 2018-05, Income Taxes (Topic 740): Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118 (SEC Update) (“ASU 2018-05”), to provide guidance for companies that have not completed their accounting for the income tax effects of the Tax Cuts and Jobs Act (the “Act”) in the period of enactment. The measurement period begins in the reporting period that includes the Act’s enactment date of December 22, 2017, and ends when a company has obtained, prepared and analyzed the information needed to complete the accounting requirements under ASU 2018-05 and should not extend beyond one year from the enactment date. The impact of adopting the new guidance on our consolidated financial position, cash flows or results of operations, as well as on related disclosures was not material. Standards Not Yet Adopted Leases (Topic 842) - In February 2016, the FASB issued ASU No. 2016-02 (“Topic 842”) Leases , which supersedes the lease recognition requirements in ASC 840, Leases . Under the new guidance, for leases with a term longer than 12 months a lessee should recognize a lease liability and a right-of-use asset representing its right to use the underlying asset for the lease term. Topic 842 retains a classification distinction between finance leases and operating leases, with the classification affecting the pattern of expense recognition in the income statement. This ASU also requires enhanced disclosures. Early adoption is permitted. We are currently assessing the impact of this new guidance via review of existing contracts that may have a lease impact and other purchase obligations that contain embedded lease features, which are generally classified as operating leases under the existing guidance. We selected a third-party consulting firm to assist us with the adoption of the new guidance. We are implementing specialized software and developing policies based on reviews performed to date of existing arrangements. We intend to complete any required changes to our systems, software applications and processes, including updating our internal controls during 2018. In 2018, the FASB also issued ASU No. 2018-01, Land Easement Practical Expedient for Transition to Topic 842 and ASU No. 2018-11, Targeted Improvements . Under these updates, optional transition practical expedients are available i) whereby existing or expired land easements that were not previously accounted for as leases under Topic 840 are not required to be evaluated under Topic 842 and ii) lease and associated non-lease components are not required to be separated within a contract if certain criteria are met. In addition, under ASU No. 2018-11, companies may initially apply the new lease requirements at the effective date. We intend to apply the new lease requirements as of January 1, 2019, recognizing a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption, and to apply the practical expedients. We are still in the process of quantifying the cumulative-effect adjustment. Financial Instruments - In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”). This guidance will become effective for interim and annual periods beginning after December 15, 2019. We expect to adopt ASU 2016-13 on January 1, 2020, and we are currently evaluating the effect that adopting this guidance will have on our consolidated financial position, results of operations and cash flows. Fair Value Measurement - In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurements (Topic 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement (“ASU 2018-13”). This guidance eliminates certain disclosure requirements for fair value measurements for all entities, requires public entities to disclose certain new information and modifies certain disclosure requirements. The FASB developed the amendments to Topic 820 as part of its broader disclosure framework project, which aims to improve the effectiveness of disclosures in the notes to financial statements by focusing on requirements that clearly communicate the most important information to users of the financial statements. This guidance will become effective for interim and annual periods beginning after December 15, 2019. We expect to adopt ASU 2018-13 on January 1, 2020, and we are currently evaluating the impact, if any, that adopting this guidance will have on our disclosures. Cloud Computing Arrangements - In August 2018, the FASB issued ASU No. 2018-15, Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract ("ASU 2018-15"). The ASU aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. The capitalized implementation costs of a hosting arrangement that is a service contract will be expensed over the term of the hosting arrangement. ASU 2018-15 is effective for annual and interim periods beginning after December 15, 2019. Early adoption is permitted, including adoption in any interim period. The amendments can be applied either retrospectively or prospectively to all implementation costs incurred after the adoption date. We expect to adopt ASU 2018-15 on January 1, 2020, and we are currently evaluating the impact, if any, that adopting this guidance will have on our accounting and disclosures. Critical Accounting Policies and Estimates See Item 7 section Critical Accounting Policies and Estimates and Item 1A. Risk Factors of the 2017 Form 10-K for additional information relating to our critical accounting policies and risk factors.
Goodwill	Goodwill - We record goodwill for the excess of the cost of an acquisition over the fair value of the net assets of the acquired business. Goodwill is reviewed for impairment at least annually, as of October 1st of each year, or more frequently if an event or change in circumstance indicates that an impairment may have occurred. We first assess qualitative factors to evaluate whether it is more likely than not that an impairment has occurred, and it is therefore necessary to perform the one-step quantitative goodwill impairment test. If the one-step quantitative goodwill impairment test indicates that the goodwill is impaired, an impairment loss is recorded, which is the difference between carrying value of the reporting unit and its fair value, with the impairment loss not to exceed the amount of goodwill recorded. When performing a quantitative impairment test, the Partnership generally determines the fair value of its reporting units using a discounted cash flow method. In the event the Partnership enters into an agreement to sell all or substantially all of a reporting unit, the Partnership will utilize such information. While using the discounted cash flow method, we must make estimates of projected cash flows related to assets, which include, but are not limited to, assumptions about revenue growth rates, operating margins, weighted average costs of capital and future market conditions, the use or disposition of assets, estimated remaining life of assets and future expenditures necessary to maintain current operations. We also must make certain estimates and assumptions, including, among other things, changes in general economic conditions in regions in which our markets are located, the availability and prices of energy commodities (such as natural gas, crude oil and refined products), our ability to negotiate favorable sales agreements, the risks that natural gas exploration and production activities will not occur or be successful, our dependence on certain significant customers and producers of natural gas and competition from other companies. Under the discounted cash flow method, the Partnership determines fair value based on estimated future cash flows and earnings before income tax, depreciation and amortization (“EBITDA”) of each reporting unit including estimates for capital expenditures, discounted to present value using the risk-adjusted industry rate, which reflects the overall level of inherent risk of the reporting unit. Cash flow projections are derived from one-year budgeted amounts and five-year operating forecasts plus an estimate of later period cash flows, all of which are evaluated by management. Subsequent period cash flows are developed for each reporting unit using growth rates that management believes are reasonably likely to occur. The annual budget process is typically completed near the annual goodwill impairment testing date, and management uses the most recent information for the annual impairment tests. The forecast is also subjected to a comprehensive update annually in conjunction with the annual budget process and is revised periodically to reflect new information and revised expectations. The estimates of future cash flows and EBITDA are subjective in nature and are subject to impacts from the business risks described in Item 1A. Risk Factors of the 2017 Form 10-K. While we believe we have made reasonable estimates and assumptions based on available information to calculate the fair value, if future results are not consistent with our estimates, changes in fair value estimates could result in additional impairments in future periods that could be material to our results of operations.

Revenue Recognition (Tables)

Revenue Recognition (Tables)	9 Months Ended
	Sep. 30, 2018
Revenue from Contract with Customer [Abstract]
Impact of New Accounting Pronouncements	The effect of adopting Topic 606, due to the change in method to measure project progress, as discussed in Note 2 - Recent Accounting Pronouncements, is as follows (in thousands): Three months ended September 30, 2018 Nine months ended September 30, 2018 As Reported Adjustments Amounts Without Adoption of Topic 606 As Reported Adjustments Amounts Without Adoption of Topic 606 Revenue Commodity sales $ 156,817 $ 10,388 $ 167,205 $ 479,923 $ 28,165 $ 508,088 Services 45,763 (9,965 ) 35,798 148,997 (24,890 ) 124,107 Operating expenses Costs of sales 150,274 6,349 156,623 461,948 14,923 476,871 Direct operating expenses 20,407 (5,248 ) 15,159 65,595 (10,254 ) 55,341 Operating income 67,164 (678 ) 66,486 47,142 (1,394 ) 45,748 Net income attributable to the Partnership 38,158 (678 ) 37,480 6,984 (1,394 ) 5,590 General Partner’s interest in net income 504 (9 ) 495 92 (18 ) 74 Limited Partners’ interest in net income 37,654 (669 ) 36,985 6,892 (1,376 ) 5,516 As of September 30, 2018 As Reported Adjustments Amounts Without Adoption of Topic 606 Assets Accounts receivable, net $ 84,819 $ (66,250 ) $ 18,569 Unbilled revenue — 66,250 66,250 Other current assets 25,971 (252 ) 25,719 Other assets, net 21,506 (7,785 ) 13,721 Liabilities Accrued expenses and other current liabilities 116,141 (905 ) 115,236 Liabilities held for sale 1,922 (665 ) 1,257 Other long-term liabilities 15,770 (14,110 ) 1,660
Disaggregation of Revenue	The following table presents our segment revenues from contracts with customers disaggregated by type of activity (in thousands): Three months ended September 30, 2018 Gas Gathering and Processing Services Liquid Pipelines and Services Natural Gas Transportation Services Offshore Pipelines and Services Terminalling Services Total Commodity sales: Natural gas $ 2,672 $ — $ 5,988 $ 2,207 $ — $ 10,867 NGLs 24,338 — — 54 — 24,392 Condensate 14,994 — — 343 — 15,337 Crude oil — 104,984 — — — 104,984 Other sales (1) 365 — 1 19 852 1,237 42,369 104,984 5,989 2,623 852 156,817 Services: Gathering and processing 10,164 — — 969 — 11,133 Transportation 241 4,540 6,565 10,203 — 21,549 Terminalling and storage — — — — 6,410 6,410 Other services (2) 655 35 156 5,536 289 6,671 11,060 4,575 6,721 16,708 6,699 45,763 Revenues from contracts with customers $ 53,429 $ 109,559 $ 12,710 $ 19,331 $ 7,551 $ 202,580 Nine months ended September 30, 2018 Gas Gathering and Processing Services Liquid Pipelines and Services Natural Gas Transportation Services Offshore Pipelines and Services Terminalling Services Total Commodity sales: Natural gas $ 8,099 $ — $ 18,098 $ 7,231 $ — $ 33,428 NGLs 63,547 — — 125 — 63,672 Condensate 34,796 — — 440 — 35,236 Crude oil — 337,281 — — — 337,281 Other sales (1) 690 — 7 83 9,526 10,306 107,132 337,281 18,105 7,879 9,526 479,923 Services: Gathering and processing 29,370 — — 874 — 30,244 Transportation 489 11,754 25,833 29,092 — 67,168 Terminalling and storage — — — — 30,393 30,393 Other services (2) 1,622 912 401 16,866 1,391 21,192 31,481 12,666 26,234 46,832 31,784 148,997 Revenues from contracts with customers $ 138,613 $ 349,947 $ 44,339 $ 54,711 $ 41,310 $ 628,920 _________________________ (1) Other commodity sales for our Terminalling Services segment include sales of Refined Products and Marine Products terminals. See Note 4 - Acquisitions and Dispositions. (2) Other services in our Offshore Pipelines and Services segment include asset management services. Other Items in Revenue The following table presents the reconciliation of our revenues from contracts with customers to segment revenues and total revenues as disclosed in our Condensed Consolidated Statements of Operations (in thousands): Three months ended September 30, 2018 Gas Gathering and Processing Services Liquid Pipelines and Services Natural Gas Transportation Services Offshore Pipelines and Services Terminalling Services Total Revenues from contracts with customers $ 53,429 $ 109,559 $ 12,710 $ 19,331 $ 7,551 $ 202,580 Loss on commodity derivatives, net (93 ) (141 ) — — — (234 ) Total revenues of reportable segments $ 53,336 $ 109,418 $ 12,710 $ 19,331 $ 7,551 $ 202,346 Nine months ended September 30, 2018 Gas Gathering and Processing Services Liquid Pipelines and Services Natural Gas Transportation Services Offshore Pipelines and Services Terminalling Services Total Revenues from contracts with customers $ 138,613 $ 349,947 $ 44,339 $ 54,711 $ 41,310 $ 628,920 Loss on commodity derivatives, net (385 ) (145 ) — — — (530 ) Total revenues of reportable segments $ 138,228 $ 349,802 $ 44,339 $ 54,711 $ 41,310 $ 628,390
Contract Balances	The following table presents the change in the contract assets and liability balances during the nine months ended September 30, 2018 (in thousands): Contract Assets Contract Liabilities Balance at December 31, 2017 $ — $ 2,136 Topic 606 implementation 2,555 13,246 Amounts recognized as revenue — (2,155 ) Additions 5,482 3,250 Contract balances included in assets/liabilities held for sale — (665 ) Balances at September 30, 2018 $ 8,037 $ 15,812 Current $ 252 $ 905 Non-current 7,785 14,907 Balances at September 30, 2018 $ 8,037 $ 15,812
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction	The following table as of September 30, 2018 , represents only revenue expected to be recognized from contracts where the price and quantity of the product or service are fixed: Remainder of 2018 2019 2020 2021 2022 Thereafter Total Gathering and processing based on minimum volume commitments $ 3,065 $ 12,667 $ 12,667 $ 12,644 $ 12,391 $ 18,289 $ 71,723 Transportation agreements 5,523 19,604 18,690 18,507 18,428 193,484 274,236 Terminalling and storage throughput agreements (1) 972 3,644 2,419 2,113 1,005 — 10,153 Other 423 1,648 1,560 — — — 3,631 Total $ 9,983 $ 37,563 $ 35,336 $ 33,264 $ 31,824 $ 211,773 $ 359,743 _________________________ (1) Represents remaining performance obligations associated with assets held-for-sale .

Acquisitions and Dispositions (

Acquisitions and Dispositions (Tables)	9 Months Ended
	Sep. 30, 2018
Discontinued Operations and Disposal Groups [Abstract]
Disposal groups and discontinued operations	Included in the disposal group are the following assets and liabilities at September 30, 2018 (in thousands): Refined Products Accounts receivable, net $ 2,170 Inventory 762 Other current assets 131 Property, plant and equipment, net 32,390 Goodwill 61,163 Intangible assets 29,403 Other non-current assets 671 Total assets held for sale $ 126,690 Accounts payable $ 227 Accrued gas purchases 108 Accrued expenses and other current liabilities 1,097 Other long-term liabilities 490 Total liabilities held for sale $ 1,922 Summarized financial information related to the Propane Business is set forth in the tables below (in thousands): Three months ended September 30, 2017 Nine months ended September 30, 2017 Total revenue $ 20,458 $ 87,615 Total operating expenses 22,489 92,196 Operating loss (2,031 ) (4,581 ) Other income 197 280 Income tax expense (15 ) (59 ) Loss from discontinued operations (1,849 ) (4,360 ) Gain from the sale of discontinued operations 46,545 46,545 Income from discontinued operations, including gain on sale $ 44,696 $ 42,185 Depreciation and amortization $ 2,355 $ 9,823 Capital expenditures $ 722 $ 3,143 Operating and investing non-cash items related to discontinued operations: (Gain) loss on sales of assets, net $ 118 $ (55 ) Unrealized loss on derivative contracts, net $ (526 ) $ 530

Inventory (Tables)

Inventory (Tables)	9 Months Ended
	Sep. 30, 2018
Inventory Disclosure [Abstract]
Schedule of Inventory	Inventory consists of the following (in thousands): September 30, 2018 December 31, 2017 Crude oil $ 2,416 $ 1,553 NGLs 544 347 Refined products — 934 Materials, supplies and equipment 120 132 Total inventory $ 3,080 $ 2,966

Other Current Assets (Tables)

Other Current Assets (Tables)	9 Months Ended
	Sep. 30, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Schedule of Other Current Assets	Other current assets consist of the following (in thousands): September 30, 2018 December 31, 2017 Prepaid expenses $ 6,049 $ 8,944 Current portion of deferred debt issuance costs (1) 5,057 — Insurance receivables 649 1,741 Due from related parties 2,461 4,362 Other receivables 4,520 5,187 Risk management assets 7,235 3,186 Total other current assets $ 25,971 $ 23,420 ___________________________________________________ (1) Related to our Credit Agreement. See Note 13 - Debt Obligations for discussion of our debt obligations.

Risk Management Activities (Tab

Risk Management Activities (Tables)	9 Months Ended
	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of notional amounts of outstanding derivative positions	The following table summarizes the net notional volumes of our outstanding commodity-related derivatives, excluding those contracts that qualified for the NPNS exception as of September 30, 2018 and December 31, 2017 , none of which were designated as hedges for accounting purposes. We had no outstanding commodity-related derivatives as of December 31, 2017 . September 30, 2018 December 31, 2017 Commodity Swaps Volume Maturity Volume Maturity NGLs Fixed Price (gallons) 831,600 January 2019 — — Crude Oil Basis (barrels) 93,000 December 2018 — —
Fair value associated with commodity derivative instruments	The following table summarizes the fair values of our derivative contracts (before netting adjustments) included in the Condensed Consolidated Balance Sheets (in thousands): Asset Derivatives Liability Derivatives Type Balance Sheet Classification September 30, December 31, 2017 September 30, December 31, 2017 Commodity derivatives Accrued expenses and other current liabilities $ — $ — $ (352 ) $ — Interest rate swaps Other current assets 6,534 2,677 — — Interest rate swaps Other assets, net 11,074 8,807 — — Weather derivatives Other current assets 701 509 — — Total $ 18,309 $ 11,993 $ (352 ) $ —
Realized and unrealized gains (losses) with commodity and interest rate derivative instruments	For each of the three and nine months ended September 30, 2018 and 2017 , the realized and unrealized gains (losses) associated with our commodity, interest rate and weather derivative instruments were recorded in our Condensed Consolidated Statements of Operations as follows (in thousands): Three months ended September 30, Nine months ended September 30, Realized Unrealized Realized Unrealized 2018 Loss on commodity derivatives, net $ (122 ) $ (112 ) $ (178 ) $ (352 ) Interest expense, net of capitalized interest 341 33 2,976 6,123 Direct operating expenses (247 ) — (797 ) — 2017 Loss on commodity derivatives, net $ (51 ) $ (546 ) $ 465 $ (498 ) Interest expense, net of capitalized interest 51 221 (19 ) (1,790 ) Direct operating expenses (278 ) — (753 ) —
Schedule of financial instruments not measured at fair value on a recurring basis	The following table presents the carrying value and estimated fair value of our financial instruments that are not measured at fair value on a recurring basis as of September 30, 2018 and December 31, 2017. Short-term and long-term debt are recorded at amortized cost in the Condensed Consolidated Balance Sheets. September 30, 2018 December 31, 2017 Carrying Amount Fair Value Carrying Amount Fair Value Non-Derivatives Liabilities 8.5% Senior Unsecured Notes $ 418,989 $ 427,154 $ 418,421 $ 437,062 3.77% Senior Secured Notes 55,342 49,792 56,005 53,845 3.97% Trans-Union Secured Senior Notes 30,390 27,118 31,692 30,221 Total $ 504,721 $ 504,064 $ 506,118 $ 521,128

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	9 Months Ended
	Sep. 30, 2018
Property, Plant and Equipment [Abstract]
Property, plant and equipment	Property, plant and equipment, net, consists of the following (in thousands): Useful Life (in years) September 30, December 31, Land Infinite $ 14,635 $ 18,145 Construction in progress N/A 54,584 55,622 Buildings and improvements 4 to 40 10,116 16,235 Transportation equipment 5 to 15 22,527 22,697 Processing and treating plants 8 to 40 123,901 123,138 Pipelines, compressors and right-of-way 3 to 40 1,022,034 974,301 Storage 3 to 40 44,418 146,105 Equipment 3 to 31 62,062 80,220 Total property, plant and equipment 1,354,277 1,436,463 Accumulated depreciation (360,357 ) (340,878 ) Property, plant and equipment, net $ 993,920 $ 1,095,585

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	Goodwill consists of the following (in thousands): September 30, 2018 December 31, 2017 Liquid Pipelines and Services $ 35,708 $ 35,708 Terminalling Services 11,043 88,466 Offshore Pipelines and Services 4,972 4,692 Total $ 51,723 $ 128,866
Schedule of Finite-Lived Intangible Assets	Intangible assets, net, consist of the following (in thousands): September 30, 2018 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Customer relationships $ 64,745 $ (16,290 ) $ 48,455 Customer contracts 94,693 (51,910 ) 42,783 Dedicated acreage 42,546 (7,248 ) 35,298 Collaborative arrangements 11,884 (2,051 ) 9,833 Noncompete agreements 1,064 (1,064 ) — Other 197 (29 ) 168 Total $ 215,129 $ (78,592 ) $ 136,537 December 31, 2017 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Customer relationships $ 110,483 $ (29,965 ) $ 80,518 Customer contracts 94,692 (48,173 ) 46,519 Dedicated acreage 42,547 (6,216 ) 36,331 Collaborative arrangements 11,884 (1,415 ) 10,469 Noncompete agreements 1,064 (1,064 ) — Other 198 (25 ) 173 Total $ 260,868 $ (86,858 ) $ 174,010

Investment in Unconsolidated _2

Investment in Unconsolidated Affiliates (Tables)	9 Months Ended
	Sep. 30, 2018
Equity Method Investments and Joint Ventures [Abstract]
Investments in and Advances to Affiliates	The following table presents the activity in our equity method investments in unconsolidated affiliates (in thousands): Delta House (1) Emerald Transactions FPS (2,4) OGL (2,4) Destin (4) Tri-States (3) Okeanos (4) Wilprise (3) Cayenne JV (3) Total Ownership % - December 31, 2017 35.7% 35.7% 66.7% 16.7% 66.7% 25.3% 50.0% Ownership % - September 30, 2018 35.7% 35.7% 66.7% 16.7% 66.7% 25.3% 50.0% Balances at December 31, 2017 $ 90,412 $ 46,932 $ 124,245 $ 53,057 $ 22,445 $ 4,689 $ 6,654 $ 348,434 Earnings in unconsolidated affiliates 14,892 8,204 8,543 2,983 8,225 664 4,231 47,742 Contributions 847 6 — — — — 4,020 4,873 Distributions (11,256 ) (12,076 ) (21,980 ) (4,701 ) (11,499 ) (848 ) (1,900 ) (64,260 ) Balances at September 30, 2018 $ 94,895 $ 43,066 $ 110,808 $ 51,339 $ 19,171 $ 4,505 $ 13,005 $ 336,789 ___________________________________________________ (1) Represents direct and indirect ownership interests in Class A units and common units. (2) FPS denotes Floating Production System LLC whereas OGL denotes Oil & Gas Lateral LLC. (3) Included in our Liquid Pipelines and Services segment. (4) Included in our Offshore Pipelines and Services segment.
Equity Method Investments	The following tables present the summarized combined financial information for our equity investments (amounts represent 100% of investee financial information) (in thousands): Balance Sheets: September 30, 2018 December 31, 2017 Current assets $ 88,702 $ 80,405 Non-current assets 1,257,275 1,288,862 Current liabilities 86,821 130,904 Non-current liabilities 470,391 436,584 Three months ended September 30, Nine months ended September 30, Statements of Operations: 2018 2017 (1) 2018 2017 (1) Revenue $ 85,504 $ 105,621 $ 194,193 $ 308,987 Operating expenses 6,665 24,168 21,172 76,145 Net income 63,078 76,650 123,226 220,617 _________________________ (1) In August 2017, we acquired 100% of the interest in POGS, the outstanding interests in one of our equity investments. We have consolidated this entity from the acquisition date. See Note 4 - Acquisitions and Dispositions for further discussion.

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	9 Months Ended
	Sep. 30, 2018
Other Liabilities Disclosure [Abstract]
Schedule of Accrued Liabilities	Accrued expenses and other current liabilities consists of the following (in thousands): September 30, 2018 December 31, 2017 Capital expenditures $ 9,069 $ 10,721 Accrued interest 14,290 3,190 Convertible preferred unit distributions 8,354 — Current portion of asset retirement obligation 3,764 6,416 Additional Blackwater acquisition consideration (see Note 19) 5,000 5,000 Taxes payable 42,350 5,263 Due to related parties 9,508 6,609 Royalties, gas imbalance and leases payables 5,734 7,905 Professional fees 4,587 1,848 Other 13,485 21,902 Total accrued expenses and other current liabilities $ 116,141 $ 68,854

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	9 Months Ended
	Sep. 30, 2018
Asset Retirement Obligation Disclosure [Abstract]
Schedule of Change in Asset Retirement Obligation	The following table presents activity in our asset retirement obligations for the nine months ended September 30, 2018 (in thousands): Current portion $ 6,416 Non-current asset retirement obligation 66,194 Balances at December 31, 2017 72,610 Additions 260 Revision in estimate (216 ) Disposals (516 ) Expenditures (3,149 ) Accretion expense 2,865 Balances at September 30, 2018 71,854 Current portion (3,764 ) Non-current asset retirement obligation $ 68,090

Debt Obligations (Tables)

Debt Obligations (Tables)	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Outstanding borrowings under the credit facility	Our outstanding debt consists of the following (in thousands): September 30, 2018 December 31, 2017 Revolving credit facility $ 600,000 $ 697,900 8.50% Senior unsecured notes, due 2021 425,000 425,000 3.77% Senior secured notes, due 2031 (non-recourse) 57,531 58,324 3.97% Senior secured notes, due 2032 (non-recourse) 30,709 32,025 Other debt — 4,989 Total debt obligations 1,113,240 1,218,238 Unamortized debt issuance costs (8,519 ) (9,231 ) Total debt 1,104,721 1,209,007 Current portion of long-term debt (603,502 ) (7,551 ) Long term debt $ 501,219 $ 1,201,456
Schedule of financial covenants	The Credit Agreement includes the following financial covenants, as amended by the Amendment and defined in the Credit Agreement, which financial covenants will be tested on a quarterly basis, for the fiscal quarter then ending: Minimum Consolidated Interest Coverage Ratio Maximum Consolidated Total Leverage Ratio Maximum Consolidated Secured Leverage Ratio June 30, 2018 2.50:1.00 6.15:1.00 4.00:1.00 September 30, 2018 2.00:1.00 6.25:1.00 3.75:1.00 December 31, 2018 1.75:1.00 5.50:1.00 3.50:1.00 March 31, 2019 1.75:1.00 5.00:1.00 (1) 3.50:1.00 June 30, 2019 and thereafter 2.00:1.00 5.00:1.00 (1) 3.50:1.00 ___________________________ (1) 5.50 :1.00 during a Specified Acquisition Period As of September 30, 2018 , we were in compliance with our Credit Agreement financial covenants, including those shown below: Ratio Actual Consolidated Interest Coverage Ratio 2.37 Consolidated Total Leverage Ratio 5.65 Consolidated Secured Leverage Ratio 3.31
Schedule of redemption percentages	On and after December 15, 2018, we may redeem all or a part of the 8.50% Senior Notes, at the redemption prices set forth below, plus accrued and unpaid interest, if redeemed during the twelve -month period beginning on December 15 of the years indicated below: Year Percentage 2018 104.250% 2019 102.125% 2020 and thereafter 100.000%

Convertible Preferred Units (Ta

Convertible Preferred Units (Tables)	9 Months Ended
	Sep. 30, 2018
Partners' Capital [Abstract]
Schedule of Preferred Units	Our convertible preferred units consist of the following (in thousands): Series A Series C Total Units $ Units $ $ December 31, 2017 10,719 $ 191,798 8,965 $ 125,382 $ 317,180 Paid in kind unit distributions 291 — 277 — — September 30, 2018 11,010 $ 191,798 9,242 $ 125,382 $ 317,180

Partners Capital (Tables)

Partners Capital (Tables)	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Schedule of Units Outstanding and Distributions	The following table details cash distributions paid or accrued as of, and for, the three and nine months ended September 30, 2018 (in thousands): Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 Series A Units Cash paid $ 4,542 $ 2,145 $ 9,084 $ 6,790 Accrued (1) 4,542 4,105 4,542 4,105 Paid-in-kind units — 1,924 3,767 6,838 Series C Units Cash paid $ 3,812 $ 3,627 $ 7,624 $ 10,880 Accrued (1) 3,812 4,150 3,812 4,150 Paid-in-kind units — — 4,309 — Series D Units Cash paid $ — $ 963 $ — $ 2,888 Limited Partners’ Units (2) Cash paid $ 5,463 $ 21,345 $ 49,061 $ 67,648 General Partner’s Units (3) Cash paid $ 72 $ 277 $ 649 $ 645 Summary Cash paid $ 13,889 $ 28,357 $ 66,418 $ 88,851 Accrued (1) 8,354 8,255 8,354 8,255 Paid-in-kind units — 1,924 8,076 6,838 __________________________ (1) Can be paid in either Cash, PIK or a combination of both. PIK payments on the Series C Units require consent of the holder. (2) Limited Partner distributions do not include $5.5 million and $21.7 million of distributions declared in the fourth quarter which relate to the third quarter of 2018 and 2017, respectively. (3) General Partner distributions do not include $0.1 million and $0.3 million of distributions declared in the fourth quarter which relate to the third quarter of 2018 and 2017, respectively. The following table presents unit activity (in thousands): General Limited Partner Units Balances at December 31, 2017 965 52,711 LTIP units vesting — 279 Issuance of GP units 16 — Balances at September 30, 2018 981 52,990
Schedule of Distributions Declared and Paid	The following table reflects distributions declared and paid through September 30, 2018 (in thousands, except per unit data): Date Declared Distribution Payment Date Period for which Distribution Relates General Partner Limited Partner Total Cash Distributions Cash Distributions Per Common Unit July 27, 2018 August 14, 2018 Second Quarter of 2018 $ 72 $ 5,463 $ 5,535 $ 0.1031 April 26, 2018 May 15, 2018 First Quarter of 2018 $ 287 $ 21,853 $ 22,140 $ 0.4125 January 26, 2018 February 14, 2018 Fourth Quarter of 2017 $ 290 $ 21,745 $ 22,035 $ 0.4125

Net Income (Loss) per Limited_2

Net Income (Loss) per Limited Partner Unit (Tables)	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Schedule of Calculation for Net Income (Loss) Per Limited Partner Unit	The calculation of basic and diluted limited partners' net income (loss) per common unit is summarized below (in thousands, except per unit amounts): Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 Income (loss) from continuing operations $ 38,183 $ 11,806 $ 7,067 $ (42,266 ) Net income attributable to noncontrolling interests (25 ) (621 ) (83 ) (3,386 ) Net income (loss) from continuing operations attributable to the Partnership 38,158 11,185 6,984 (45,652 ) Distributions on Series A Units (4,542 ) (4,105 ) (13,626 ) (12,472 ) Distributions on Series C Units (3,812 ) (4,150 ) (11,437 ) (11,403 ) Distributions on Series D Units — — — (1,925 ) General Partner's distribution (73 ) (287 ) (434 ) (763 ) General Partner's share in undistributed (loss) income (303 ) 210 683 1,729 Income (loss) from continuing operations attributable to Limited Partners 29,428 2,853 (17,830 ) (70,486 ) Income from discontinued operations, net of tax — 44,696 — 42,185 Net income (loss) attributable to Limited Partners $ 29,428 $ 47,549 $ (17,830 ) $ (28,301 ) Weighted average number of common units outstanding: Basic 52,984 52,021 52,917 52,021 Potentially dilutive common unit equivalents (1) 22,541 — — — Diluted 75,525 52,021 52,917 52,021 Limited Partners' net income (loss) per common unit - Basic and Diluted Basic: Income (loss) from continuing operations $ 0.56 $ 0.05 $ (0.34 ) $ (1.35 ) Income (loss) from discontinued operations — 0.86 — 0.81 Net income (loss) $ 0.56 $ 0.91 $ (0.34 ) $ (0.54 ) Diluted: Income (loss) from continuing operations $ 0.39 $ 0.05 $ (0.34 ) $ (1.35 ) Income (loss) from discontinued operations — 0.86 — 0.81 Net income (loss) $ 0.39 $ 0.91 $ (0.34 ) $ (0.54 ) _____________________________________ (1) Potential common unit equivalents were antidilutive for the three months ended September 30, 2017 and for the nine months ended September 30, 2018 and 2017. As a result, 24.9 million potential common unit equivalents for the three months ended September 30, 2017 and 23.4 million potential common unit equivalents and 24.8 million potential common unit equivalents for the nine months ended September 30, 2018 and 2017, respectively, have been excluded from the determination of diluted limited partners' net income (loss) per common unit.

Incentive Compensation (Tables)

Incentive Compensation (Tables)	9 Months Ended
	Sep. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Components of Equity-Based Compensation Expense	The following table presents the components of equity-based compensation expense for the three and nine months ended September 30, 2018 and 2017 (in thousands): Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 Grant Type: RSU $ 1,083 $ 815 $ 2,616 $ 6,010 PSU 237 — 867 — Options 15 19 46 57 Total $ 1,335 $ 834 $ 3,529 $ 6,067

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	9 Months Ended
	Sep. 30, 2018
Supplemental Cash Flow Elements [Abstract]
Schedule of Supplemental Cash Flow Information	Supplemental cash flows and non-cash transactions consist of the following (in thousands): Nine months ended September 30, 2018 2017 Supplemental cash flow information Cash paid for interest $ 49,294 $ 40,885 Supplemental non-cash information Investing Increase (decrease) in accrued property, plant and equipment purchases (1,652 ) (15,112 ) Accrued contributions to unconsolidated affiliates (89 ) — Financing Issuance of common units for the Panther acquisition — 12,532 Contributions from an affiliate holding limited partner interests — 4,000 Accrued distributions on convertible preferred units 8,354 8,255 Paid-in-kind distributions on convertible preferred units 8,076 6,838

Reportable Segments (Tables)

Reportable Segments (Tables)	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Segment information	The following tables set forth our segment information for the three and nine months ended September 30, 2018 and 2017 (in thousands): Three months ended September 30, 2018 Gas Gathering and Processing Services Liquid Pipelines and Services Natural Gas Transportation Services Offshore Pipelines and Services Terminalling Services Total Revenue $ 53,429 $ 109,559 $ 12,710 $ 19,331 $ 7,551 $ 202,580 Loss on commodity derivatives, net (93 ) (141 ) — — — (234 ) Total revenue 53,336 109,418 12,710 19,331 7,551 202,346 Operating expenses: Cost of sales 37,917 103,345 5,502 1,959 1,551 150,274 Direct operating expenses — — — — 2,152 20,407 Corporate expenses 23,857 Termination fee 17,000 Depreciation, amortization and accretion expense 23,040 Gain on sale of assets, net (99,396 ) Total operating expenses 135,182 Operating income 67,164 Other income (expense), net Interest expense, net of capitalized interest (22,267 ) Other expense, net (128 ) Earnings in unconsolidated affiliates — 3,172 — 21,450 — 24,622 Income from continuing operations before income taxes 69,391 Income tax expense (31,208 ) Income from continuing operations 38,183 Net income attributable to non-controlling interests (25 ) Net income attributable to the Partnership $ 38,158 Segment gross margin $ 15,421 $ 9,351 $ 7,044 $ 38,823 $ 3,848 Three months ended September 30, 2017 Gas Gathering and Processing Services Liquid Pipelines and Services Natural Gas Transportation Services Offshore Pipelines and Services Terminalling Services Total Revenue $ 37,287 $ 87,022 $ 11,131 $ 14,360 $ 13,087 $ 162,887 Loss on commodity derivatives, net (65 ) (532 ) — — — (597 ) Total revenue 37,222 86,490 11,131 14,360 13,087 162,290 Operating expenses: Cost of sales 24,492 80,510 5,692 558 1,146 112,398 Direct operating expenses 3,432 20,705 Corporate expenses 27,083 Depreciation, amortization and accretion expense 26,781 Gain on sale of assets, net (4,061 ) Total operating expenses 182,906 Operating loss (20,616 ) Other income (expenses), net Interest expense, net of capitalized interest (17,759 ) Other income, net 34,085 Earnings in unconsolidated affiliates — 1,317 — 15,510 — 16,827 Income from continuing operations before income taxes 12,537 Income tax expense (731 ) Income from continuing operations 11,806 Income from discontinued operations, including gain on disposition 44,696 Net income 56,502 Net income attributable to non-controlling interests (621 ) Net income attributable to the Partnership $ 55,881 Segment gross margin $ 12,761 $ 7,808 $ 5,356 $ 29,312 $ 8,509 Nine months ended September 30, 2018 Gas Gathering and Processing Services Liquid Pipelines and Services Natural Gas Transportation Services Offshore Pipelines and Services Terminalling Services Total Revenue $ 138,613 $ 349,947 $ 44,339 $ 54,711 $ 41,310 $ 628,920 Loss on commodity derivatives, net (385 ) (145 ) — — — (530 ) Total revenue 138,228 349,802 44,339 54,711 41,310 628,390 Operating expenses: Cost of sales 95,921 333,342 16,628 6,105 9,952 461,948 Direct operating expenses — — — — 10,605 65,595 Corporate expenses 69,922 Termination fee 17,000 Depreciation, amortization and accretion expense 66,274 Gain on sale of assets, net (99,491 ) Total operating expenses 581,248 Operating income 47,142 Other income (expense), net Interest expense, net of capitalized interest (55,834 ) Other income, net 62 Earnings in unconsolidated affiliates — 7,878 — 39,864 — 47,742 Income from continuing operations before income taxes 39,112 Income tax expense (32,045 ) Net income 7,067 Net income attributable to non-controlling interests (83 ) Net income attributable to the Partnership $ 6,984 Segment gross margin $ 42,613 $ 24,365 $ 27,384 $ 88,470 $ 20,753 Nine months ended September 30, 2017 Gas Gathering and Processing Services Liquid Pipelines and Services Natural Gas Transportation Services Offshore Pipelines and Services Terminalling Services Total Revenue $ 111,001 $ 253,590 $ 34,966 $ 41,330 $ 47,544 $ 488,431 (Loss) gain on commodity derivatives, net (170 ) 137 — — — (33 ) Total revenue 110,831 253,727 34,966 41,330 47,544 488,398 Operating expenses: Cost of sales 74,261 236,896 17,630 6,487 7,612 342,886 Direct operating expenses — — — — 9,503 56,819 Corporate expenses 84,570 Depreciation, amortization and accretion expense 78,834 Gain on sale of assets, net (4,064 ) Total operating expenses 559,045 Operating loss (70,647 ) Other income (expenses), net Interest expense, net of capitalized interest (51,037 ) Other income, net 32,248 Earnings in unconsolidated affiliates — 3,886 — 45,895 — 49,781 Loss from continuing operations before income taxes (39,655 ) Income tax expense (2,611 ) Loss from continuing operations (42,266 ) Income from discontinued operations, including gain on disposition 42,185 Net loss (81 ) Net income attributable to non-controlling interests (3,386 ) Net loss attributable to the Partnership $ (3,467 ) Segment gross margin $ 36,663 $ 21,209 $ 17,106 $ 80,738 $ 30,429 A reconciliation of total assets by segment to the amounts included in the Condensed Consolidated Balance Sheets follows (in thousands): September 30, December 31, 2018 2017 Segment assets: Gas Gathering and Processing Services $ 397,726 $ 404,872 Liquid Pipelines and Services 370,833 359,646 Natural Gas Transportation Services 267,185 268,991 Offshore Pipelines and Services 525,493 553,213 Terminalling Services 187,779 293,085 Other (1) 85,589 43,659 Total assets $ 1,834,605 $ 1,923,466 Investment in unconsolidated affiliates: Liquid Pipelines and Services $ 68,849 $ 64,399 Offshore Pipelines and Services 267,940 284,035 Total investment in unconsolidated affiliates $ 336,789 $ 348,434 ________________________ (1) Other assets consists primarily of corporate assets not allocable to segments, such as leasehold improvements and other current assets. The following table sets forth capital expenditures for the three and nine months ended September 30, 2018 and 2017 by segment (in thousands): Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 Capital expenditures Gas Gathering and Processing Services $ 11,603 $ 4,788 $ 24,914 $ 13,315 Liquid Pipelines and Services 1,468 1,301 12,649 2,677 Natural Gas Transportation Services 1,554 6,431 4,045 30,797 Offshore Pipelines and Services 155 2,283 20,491 3,417 Terminalling Services 691 3,954 6,813 6,795 Corporate 1,358 1,235 4,430 4,882 Total capital expenditures (1) $ 16,829 $ 19,992 $ 73,342 $ 61,883 _____________________________________ (1) Capital expenditures exclude expenditures made for the Propane Business of $0.7 million and $ 3.1 million for the three and nine months ended September 30, 2017 , respectively, as the business was sold in 2017

Organization and Basis of Pre_3

Organization and Basis of Presentation (Details)	9 Months Ended
	Sep. 30, 2018segments
Organization, Consolidation and Presentation of Financial Statements [Abstract]
General partners' capital account (percent)	77.00%
Limited partners' capital account (percent)	23.00%
Number of reportable segments	5

Recent Accounting Pronounceme_2

Recent Accounting Pronouncements and Critical Accounting Policies - Effect of Adoption of New Accounting Pronouncements (Details) $ in Thousands	3 Months Ended	6 Months Ended		9 Months Ended		12 Months Ended
	Mar. 31, 2018USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Sep. 30, 2018USD ($)unit	Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)unit
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by (used in) operating activities				$ 12,944	$ 15,005
Net cash provided by (used in) investing activities				151,848	1,986
Goodwill				51,723		$ 128,866
ASU 2016-15 | Effect of Adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by (used in) operating activities					(9,400)
Net cash provided by (used in) investing activities					9,400
ASU 2016-18 | Effect of Adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restricted cash outflows					3,500
Restricted cash inflows					302,700
Liquid Pipelines and Services
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Goodwill				35,708		35,708
Terminalling Services
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Goodwill				$ 11,043		88,466
Seven Reporting Units [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Goodwill						$ 128,900
Number of reporting units | unit						7
Cushing and Silver Dollar Reporting Units
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Goodwill						$ 46,800
Number of reporting units | unit						2
Silver Dollar Reporting Unit | Liquid Pipelines and Services
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Goodwill						$ 35,700
Cushing Reporting Unit | Terminalling Services
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Goodwill						$ 11,100
Excess of fair value over carrying value (percent)						7.00%
Three Reporting Units [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of reporting units | unit				3
Held-for-sale
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Goodwill				$ 61,200
Held-for-sale | Two Reporting Units [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of reporting units | unit				2
Propane Business | ASU 2016-15 | Effect of Adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by (used in) operating activities					2,500
Net cash provided by (used in) investing activities					$ (2,500)
Error in presentation of distributions from unconsolidated affiliates in Condensed Consolidated Statements of Cash Flows | (Overstated) Understated
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by (used in) operating activities	$ (2,500)	$ 1,000	$ (6,300)
Net cash provided by (used in) investing activities	$ (2,500)	$ 1,000	$ (6,300)

Revenue Recognition - Impact of

Revenue Recognition - Impact of Adopting New Accounting Pronouncement on income Statement (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	$ 202,580	$ 162,887	$ 628,920	$ 488,431
Cost of Sales	150,274	112,398	461,948	342,886
Direct operating expenses	20,407	20,705	65,595	56,819
Operating income (loss)	67,164	(20,616)	47,142	(70,647)
Net income (loss) attributable to the Partnership	38,158	55,881	6,984	(3,467)
General Partner’s interest in net income	504	697	92	(98)
Limited Partners’ interest in net income	37,654	55,184	6,892	(3,369)
Adjustments | ASU 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Cost of Sales	6,349		14,923
Direct operating expenses	(5,248)		(10,254)
Operating income (loss)	(678)		(1,394)
Net income (loss) attributable to the Partnership	(678)		(1,394)
General Partner’s interest in net income	(9)		(18)
Limited Partners’ interest in net income	(669)		(1,376)
Amounts Without Adoption of Topic 606 | ASU 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Cost of Sales	156,623		476,871
Direct operating expenses	15,159		55,341
Operating income (loss)	66,486		45,748
Net income (loss) attributable to the Partnership	37,480		5,590
General Partner’s interest in net income	495		74
Limited Partners’ interest in net income	36,985		5,516
Commodity sales
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	156,817	124,052	479,923	372,049
Commodity sales | Adjustments | ASU 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	10,388		28,165
Commodity sales | Amounts Without Adoption of Topic 606 | ASU 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	167,205		508,088
Services
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	45,763	$ 38,835	148,997	$ 116,382
Services | Adjustments | ASU 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	(9,965)		(24,890)
Services | Amounts Without Adoption of Topic 606 | ASU 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	$ 35,798		$ 124,107

Revenue Recognition - Impact _2

Revenue Recognition - Impact of Adopting New Accounting Pronouncement on Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable, net	$ 84,819	$ 98,132
Unbilled revenue	0
Other current assets	25,971	23,420
Other assets, net	21,506	17,874
Accrued expenses and other current liabilities	116,141	68,854
Liabilities held for sale	1,922	0
Other long-term liabilities	15,770	$ 2,080
Adjustments | ASU 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable, net	(66,250)
Unbilled revenue	66,250
Other current assets	(252)
Other assets, net	(7,785)
Accrued expenses and other current liabilities	(905)
Liabilities held for sale	(665)
Other long-term liabilities	(14,110)
Amounts Without Adoption of Topic 606 | ASU 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable, net	18,569
Unbilled revenue	66,250
Other current assets	25,719
Other assets, net	13,721
Accrued expenses and other current liabilities	115,236
Liabilities held for sale	1,257
Other long-term liabilities	$ 1,660

Revenue Recognition - Disaggreg

Revenue Recognition - Disaggregated Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 202,580	$ 162,887	$ 628,920	$ 488,431
Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	156,817	124,052	479,923	372,049
Gathering and processing
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	11,133		30,244
Transportation
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	21,549		67,168
Terminalling and storage
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	6,410		30,393
Other services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	6,671		21,192
Services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	45,763	$ 38,835	148,997	$ 116,382
Gas Gathering and Processing Services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	53,429		138,613
Gas Gathering and Processing Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	42,369		107,132
Gas Gathering and Processing Services | Gathering and processing
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	10,164		29,370
Gas Gathering and Processing Services | Transportation
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	241		489
Gas Gathering and Processing Services | Terminalling and storage
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0		0
Gas Gathering and Processing Services | Other services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	655		1,622
Gas Gathering and Processing Services | Services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	11,060		31,481
Liquid Pipelines and Services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	109,559		349,947
Liquid Pipelines and Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	104,984		337,281
Liquid Pipelines and Services | Gathering and processing
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0		0
Liquid Pipelines and Services | Transportation
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	4,540		11,754
Liquid Pipelines and Services | Terminalling and storage
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0		0
Liquid Pipelines and Services | Other services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	35		912
Liquid Pipelines and Services | Services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	4,575		12,666
Natural Gas Transportation Services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	12,710		44,339
Natural Gas Transportation Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	5,989		18,105
Natural Gas Transportation Services | Gathering and processing
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0		0
Natural Gas Transportation Services | Transportation
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	6,565		25,833
Natural Gas Transportation Services | Terminalling and storage
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0		0
Natural Gas Transportation Services | Other services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	156		401
Natural Gas Transportation Services | Services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	6,721		26,234
Offshore Pipelines and Services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	19,331		54,711
Offshore Pipelines and Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	2,623		7,879
Offshore Pipelines and Services | Gathering and processing
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	969		874
Offshore Pipelines and Services | Transportation
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	10,203		29,092
Offshore Pipelines and Services | Terminalling and storage
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0		0
Offshore Pipelines and Services | Other services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	5,536		16,866
Offshore Pipelines and Services | Services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	16,708		46,832
Terminalling Services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	7,551		41,310
Terminalling Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	852		9,526
Terminalling Services | Gathering and processing
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0		0
Terminalling Services | Transportation
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0		0
Terminalling Services | Terminalling and storage
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	6,410		30,393
Terminalling Services | Other services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	289		1,391
Terminalling Services | Services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	6,699		31,784
Natural gas | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	10,867		33,428
Natural gas | Gas Gathering and Processing Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	2,672		8,099
Natural gas | Liquid Pipelines and Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0		0
Natural gas | Natural Gas Transportation Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	5,988		18,098
Natural gas | Offshore Pipelines and Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	2,207		7,231
Natural gas | Terminalling Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0		0
NGLs | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	24,392		63,672
NGLs | Gas Gathering and Processing Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	24,338		63,547
NGLs | Liquid Pipelines and Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0		0
NGLs | Natural Gas Transportation Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0		0
NGLs | Offshore Pipelines and Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	54		125
NGLs | Terminalling Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0		0
Condensate | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	15,337		35,236
Condensate | Gas Gathering and Processing Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	14,994		34,796
Condensate | Liquid Pipelines and Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0		0
Condensate | Natural Gas Transportation Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0		0
Condensate | Offshore Pipelines and Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	343		440
Condensate | Terminalling Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0		0
Crude oil | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	104,984		337,281
Crude oil | Gas Gathering and Processing Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0		0
Crude oil | Liquid Pipelines and Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	104,984		337,281
Crude oil | Natural Gas Transportation Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0		0
Crude oil | Offshore Pipelines and Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0		0
Crude oil | Terminalling Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0		0
Other sales | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,237		10,306
Other sales | Gas Gathering and Processing Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	365		690
Other sales | Liquid Pipelines and Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0		0
Other sales | Natural Gas Transportation Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1		7
Other sales | Offshore Pipelines and Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	19		83
Other sales | Terminalling Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 852		$ 9,526

Revenue Recognition - Reconcili

Revenue Recognition - Reconciliation of Revenues From Contracts With Customers (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 202,580	$ 162,887	$ 628,920	$ 488,431
Loss on commodity derivatives, net	(234)	(597)	(530)	(33)
Total revenue	202,346	162,290	628,390	488,398
Gas Gathering and Processing Services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	53,429		138,613
Loss on commodity derivatives, net	(93)		(385)
Total revenue	53,336		138,228
Liquid Pipelines and Services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	109,559		349,947
Loss on commodity derivatives, net	(141)		(145)
Total revenue	109,418		349,802
Natural Gas Transportation Services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	12,710		44,339
Loss on commodity derivatives, net	0		0
Total revenue	12,710		44,339
Offshore Pipelines and Services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	19,331		54,711
Loss on commodity derivatives, net	0		0
Total revenue	19,331		54,711
Terminalling Services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	7,551		41,310
Loss on commodity derivatives, net	0		0
Total revenue	7,551		41,310
Operating Segments | Gas Gathering and Processing Services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	53,429	37,287	138,613	111,001
Loss on commodity derivatives, net	(93)	(65)	(385)	(170)
Total revenue	53,336	37,222	138,228	110,831
Operating Segments | Liquid Pipelines and Services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	109,559	87,022	349,947	253,590
Loss on commodity derivatives, net	(141)	(532)	(145)	137
Total revenue	109,418	86,490	349,802	253,727
Operating Segments | Natural Gas Transportation Services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	12,710	11,131	44,339	34,966
Loss on commodity derivatives, net	0	0	0	0
Total revenue	12,710	11,131	44,339	34,966
Operating Segments | Offshore Pipelines and Services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	19,331	14,360	54,711	41,330
Loss on commodity derivatives, net	0	0	0	0
Total revenue	19,331	14,360	54,711	41,330
Operating Segments | Terminalling Services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	7,551	13,087	41,310	47,544
Loss on commodity derivatives, net	0	0	0	0
Total revenue	$ 7,551	$ 13,087	$ 41,310	$ 47,544

Revenue Recognition - Change in

Revenue Recognition - Change in Contract Balances (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018
Contract Assets
Balances at September 30, 2018	$ 8,037
Current		$ 252
Non-current		7,785
Accounts receivable, net	8,037	8,037
Contract Liabilities
Balances at September 30, 2018	15,812
Current	905
Non-current	14,907
Contract with Customer, Liability	15,812	15,812
Held-for-sale
Contract Assets
Balances at September 30, 2018	0
Accounts receivable, net	0	0
Contract Liabilities
Balances at September 30, 2018	665
Contract with Customer, Liability	665	665
Continuing Operations, Including Assets Held for Sale
Contract Assets
Balance at December 31, 2017	0
Topic 606 implementation	2,555
Additions	5,482
Balances at September 30, 2018	8,037
Accounts receivable, net	0	8,037
Contract Liabilities
Balance at December 31, 2017	2,136
Topic 606 implementation	13,246
Amounts recognized as revenue	(2,155)
Additions	3,250
Balances at September 30, 2018	15,812
Contract with Customer, Liability	$ 2,136	$ 15,812

Revenue Recognition - Remaining

Revenue Recognition - Remaining Performance Obligation (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)
Revenue from Contract with Customer [Abstract]
Remaining performance obligation - optional exemption election	Certain contracts have not been presented in the table above due to the term being one year or less and due to variability in the amount of performance obligation remaining, variability in the timing of recognition or variability in consideration.
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 9,983
Remaining performance obligation satisfaction period	3 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 37,563
Remaining performance obligation satisfaction period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 35,336
Remaining performance obligation satisfaction period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 33,264
Remaining performance obligation satisfaction period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 31,824
Remaining performance obligation satisfaction period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 211,773
Remaining performance obligation satisfaction period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 359,743
Remaining performance obligation satisfaction period	1 year
Gathering and processing based on minimum volume commitments | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 3,065
Remaining performance obligation satisfaction period	3 months
Gathering and processing based on minimum volume commitments | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 12,667
Remaining performance obligation satisfaction period	1 year
Gathering and processing based on minimum volume commitments | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 12,667
Remaining performance obligation satisfaction period	1 year
Gathering and processing based on minimum volume commitments | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 12,644
Remaining performance obligation satisfaction period	1 year
Gathering and processing based on minimum volume commitments | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 12,391
Remaining performance obligation satisfaction period	1 year
Gathering and processing based on minimum volume commitments | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 18,289
Remaining performance obligation satisfaction period	1 year
Gathering and processing based on minimum volume commitments | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 71,723
Remaining performance obligation satisfaction period	1 year
Transportation agreements | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 5,523
Remaining performance obligation satisfaction period	3 months
Transportation agreements | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 19,604
Remaining performance obligation satisfaction period	1 year
Transportation agreements | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 18,690
Remaining performance obligation satisfaction period	1 year
Transportation agreements | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 18,507
Remaining performance obligation satisfaction period	1 year
Transportation agreements | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 18,428
Remaining performance obligation satisfaction period	1 year
Transportation agreements | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 193,484
Remaining performance obligation satisfaction period	1 year
Transportation agreements | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 274,236
Remaining performance obligation satisfaction period	1 year
Terminalling and storage throughput agreements | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 972
Remaining performance obligation satisfaction period	3 months
Terminalling and storage throughput agreements | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 3,644
Remaining performance obligation satisfaction period	1 year
Terminalling and storage throughput agreements | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 2,419
Remaining performance obligation satisfaction period	1 year
Terminalling and storage throughput agreements | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 2,113
Remaining performance obligation satisfaction period	1 year
Terminalling and storage throughput agreements | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 1,005
Remaining performance obligation satisfaction period	1 year
Terminalling and storage throughput agreements | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 0
Remaining performance obligation satisfaction period	1 year
Terminalling and storage throughput agreements | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 10,153
Remaining performance obligation satisfaction period	1 year
Other services | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 423
Remaining performance obligation satisfaction period	3 months
Other services | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 1,648
Remaining performance obligation satisfaction period	1 year
Other services | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 1,560
Remaining performance obligation satisfaction period	1 year
Other services | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 0
Remaining performance obligation satisfaction period	1 year
Other services | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 0
Remaining performance obligation satisfaction period	1 year
Other services | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 0
Remaining performance obligation satisfaction period	1 year
Other services | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 3,631
Remaining performance obligation satisfaction period	1 year

Acquisitions and Dispositions_2

Acquisitions and Dispositions (Narrative) (Details) $ in Thousands

Jul. 31, 2018USD ($)

Nov. 03, 2017USD ($)

Oct. 27, 2017USD ($)

Sep. 29, 2017USD ($)

Sep. 01, 2017USD ($)location

Aug. 08, 2017USD ($)

Jun. 02, 2017USD ($)

Aug. 31, 2018USD ($)

Sep. 30, 2017USD ($)

Sep. 30, 2018USD ($)

Sep. 30, 2017USD ($)

Feb. 16, 2018USD ($)

Oct. 31, 2017USD ($)

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Payments to acquire equity method investments

$ 5,867

$ 49,828

Total consideration under the merger agreement

$ 818,000

Payments for termination fee

$ 17,000

Refined Products Terminals And Storage Segment

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Sale price per definitive agreement

$ 138,500

Marine Liquids Terminals | Not Discontinued Operations

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Proceeds from sale of business and assets, net of cash on hand

$ 208,600

Advisory fees and other transaction costs

5,700

Gain from the sale of discontinued operations

99,400

Tax expense associated with the gain on disposal

$ 29,800

Propane Marketing Services | Discontinued Operations

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Proceeds from sale of business and assets, net of cash on hand

$ 170,000

Advisory fees and other transaction costs

2,500

Gain from the sale of discontinued operations

$ 46,500

Propane Marketing Services | Propane Business | Discontinued Operations

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Number of service locations divested | location

40

Gain from the sale of discontinued operations

$ 46,545

$ 46,545

Destin | American Midstream Emerald, LLC

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Equity interests acquired (percent)

17.00%

Total consideration upon acquisition

$ 30,000

Delta House

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Equity interests acquired (percent)

15.50%

Payments to acquire equity method investments

$ 125,400

Viosca Knoll

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Equity interests acquired (percent)

100.00%

Cash payment made to acquire business

$ 32,000

Panther

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Equity interests acquired (percent)

100.00%

Total consideration upon acquisition

$ 60,900

Trans-Union Pipeline, L.P. (“Trans-Union”)

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Equity interests acquired (percent)

100.00%

Cash payment made to acquire business

$ 16,900

Total consideration upon acquisition

49,400

Non-recourse debt assumed

$ 32,500

Acquisitions and Dispositions_3

Acquisitions and Dispositions (Condensed Balance Sheets) (Details) - Refined Products Business - Refined Products Terminals And Storage Segment - Held-for-sale $ in Thousands	Sep. 30, 2018USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accounts receivable, net	$ 2,170
Inventory	762
Other current assets	131
Property, plant and equipment, net	32,390
Goodwill	61,163
Intangible assets	29,403
Other non-current assets	671
Total assets held for sale	126,690
Accounts payable	227
Accrued gas purchases	108
Accrued expenses and other current liabilities	1,097
Other long-term liabilities	490
Total liabilities held for sale	$ 1,922

Acquisitions and Dispositions_4

Acquisitions and Dispositions (Condensed Statements of Operations) (Details) - USD ($) $ in Thousands	Sep. 01, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss from discontinued operations		$ 0	$ 44,696	$ 0	$ 42,185
Propane Marketing Services | Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain from the sale of discontinued operations	$ 46,500
Propane Business | Propane Marketing Services | Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total revenue			20,458		87,615
Total operating expenses			22,489		92,196
Operating loss			(2,031)		(4,581)
Other income			197		280
Income tax expense			(15)		(59)
Loss from discontinued operations			(1,849)		(4,360)
Gain from the sale of discontinued operations			46,545		46,545
Income from discontinued operations, including gain on sale			44,696		42,185
Depreciation and amortization			2,355		9,823
Capital expenditures			722		3,143
(Gain) loss on sales of assets, net			118		(55)
Unrealized loss on derivative contracts, net			$ (526)		$ 530

Inventory (Details)

Inventory (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Crude oil	$ 2,416	$ 1,553
NGLs	544	347
Refined products	0	934
Materials, supplies and equipment	120	132
Total inventory	$ 3,080	$ 2,966

Other Current Assets (Details)

Other Current Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid expenses	$ 6,049	$ 8,944
Current portion of deferred debt issuance costs	5,057	0
Insurance receivables	649	1,741
Due from related parties	2,461	4,362
Other receivables	4,520	5,187
Risk management assets	7,235	3,186
Total other current assets	$ 25,971	$ 23,420

Risk Management Activities (Com

Risk Management Activities (Commodity-related Derivatives) (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2018galbbl	Dec. 31, 2017galbbl
Propane | NGLs, Fixed Price Commodity Swap Contract
Derivative [Line Items]
Derivative, volume | gal	831,600	0
Crude oil | Crude Oil, Basis Commodity Swap Contract
Derivative [Line Items]
Derivative, volume | bbl	93,000,000	0

Risk Management Activities (Int

Risk Management Activities (Interest Rate Swaps) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Interest rate swaps
Derivative [Line Items]
Notional amount	$ 550	$ 550

Risk Management Activities (Nar

Risk Management Activities (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Derivative [Line Items]
Total			$ 18,309,000		$ 11,993,000
Interest rate swaps
Derivative [Line Items]
Notional amount			550,000,000		550,000,000
Weather Derivative
Derivative [Line Items]
Potential proceeds from derivative contract	$ 20,000,000	$ 30,000,000
Premium payments			$ 1,000,000	$ 1,100,000
Term of contract			1 year
Other current assets | Interest rate swaps
Derivative [Line Items]
Total			$ 6,534,000		2,677,000
Other current assets | Weather Derivative
Derivative [Line Items]
Total			$ 701,000		$ 509,000

Risk Management Activities (Fai

Risk Management Activities (Fair Value of Commodity Derivatives) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Asset Derivatives
Total	$ 18,309	$ 11,993
Liability Derivatives
Total	(352)	0
Accrued Expenses and Other Liabilities | Commodity derivatives
Asset Derivatives
Total	0	0
Liability Derivatives
Total	(352)	0
Other current assets | Interest rate swaps
Asset Derivatives
Total	6,534	2,677
Liability Derivatives
Total	0	0
Other current assets | Weather derivatives
Asset Derivatives
Total	701	509
Liability Derivatives
Total	0	0
Other assets, net | Interest rate swaps
Asset Derivatives
Total	11,074	8,807
Liability Derivatives
Total	$ 0	$ 0

Risk Management Activities (Rea

Risk Management Activities (Realized and Unrealized Gains (Losses)) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Derivatives, Fair Value [Line Items]
Realized	$ (234)	$ (597)	$ (530)	$ (33)
Commodity Contract
Derivatives, Fair Value [Line Items]
Realized
Unrealized
Commodity Contract | Loss on commodity derivatives, net
Derivatives, Fair Value [Line Items]
Realized	(122)	(51)	(178)	465
Unrealized	(112)	(546)	(352)	(498)
Commodity Contract | Interest expense, net of capitalized interest
Derivatives, Fair Value [Line Items]
Realized	341	51	2,976	(19)
Unrealized	33	221	6,123	(1,790)
Commodity Contract | Direct operating expenses
Derivatives, Fair Value [Line Items]
Realized	(247)	(278)	(797)	(753)
Unrealized	$ 0	$ 0	$ 0	$ 0

Risk Management Activities (Fin

Risk Management Activities (Financial Instruments Not Measured at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	$ 504,721	$ 506,118
Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	$ 504,064	521,128
8.5% Senior Unsecured Notes | Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument, stated interest rate (percent)	8.50%
8.5% Senior Unsecured Notes | Carrying Amount | Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	$ 418,989	418,421
8.5% Senior Unsecured Notes | Fair Value | Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	$ 427,154	437,062
3.77% Senior Secured Notes | Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument, stated interest rate (percent)	3.77%
3.77% Senior Secured Notes | Carrying Amount | Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	$ 55,342	56,005
3.77% Senior Secured Notes | Fair Value | Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	$ 49,792	53,845
3.97% Trans-Union Secured Senior Notes | Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument, stated interest rate (percent)	3.97%
3.97% Trans-Union Secured Senior Notes | Carrying Amount | Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	$ 30,390	31,692
3.97% Trans-Union Secured Senior Notes | Fair Value | Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	$ 27,118	$ 30,221

Property, Plant and Equipment_2

Property, Plant and Equipment (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Property, Plant and Equipment, Net [Abstract]
Total property, plant and equipment	$ 1,354,277	$ 1,436,463
Accumulated depreciation	(360,357)	(340,878)
Property, plant and equipment, net	993,920	1,095,585
Land
Property, Plant and Equipment, Net [Abstract]
Total property, plant and equipment	14,635	18,145
Construction in progress
Property, Plant and Equipment, Net [Abstract]
Total property, plant and equipment	54,584	55,622
Buildings and improvements
Property, Plant and Equipment, Net [Abstract]
Total property, plant and equipment	10,116	16,235
Transportation equipment
Property, Plant and Equipment, Net [Abstract]
Total property, plant and equipment	22,527	22,697
Processing and treating plants
Property, Plant and Equipment, Net [Abstract]
Total property, plant and equipment	123,901	123,138
Pipelines, compressors and right-of-way
Property, Plant and Equipment, Net [Abstract]
Total property, plant and equipment	1,022,034	974,301
Storage
Property, Plant and Equipment, Net [Abstract]
Total property, plant and equipment	44,418	146,105
Equipment
Property, Plant and Equipment, Net [Abstract]
Total property, plant and equipment	$ 62,062	$ 80,220
Minimum | Buildings and improvements
Property, Plant and Equipment, Net [Abstract]
Useful Life (in years)	4 years
Minimum | Transportation equipment
Property, Plant and Equipment, Net [Abstract]
Useful Life (in years)	5 years
Minimum | Processing and treating plants
Property, Plant and Equipment, Net [Abstract]
Useful Life (in years)	8 years
Minimum | Pipelines, compressors and right-of-way
Property, Plant and Equipment, Net [Abstract]
Useful Life (in years)	3 years
Minimum | Storage
Property, Plant and Equipment, Net [Abstract]
Useful Life (in years)	3 years
Minimum | Equipment
Property, Plant and Equipment, Net [Abstract]
Useful Life (in years)	3 years
Maximum | Buildings and improvements
Property, Plant and Equipment, Net [Abstract]
Useful Life (in years)	40 years
Maximum | Transportation equipment
Property, Plant and Equipment, Net [Abstract]
Useful Life (in years)	15 years
Maximum | Processing and treating plants
Property, Plant and Equipment, Net [Abstract]
Useful Life (in years)	40 years
Maximum | Pipelines, compressors and right-of-way
Property, Plant and Equipment, Net [Abstract]
Useful Life (in years)	40 years
Maximum | Storage
Property, Plant and Equipment, Net [Abstract]
Useful Life (in years)	40 years
Maximum | Equipment
Property, Plant and Equipment, Net [Abstract]
Useful Life (in years)	31 years

Property, Plant and Equipment_3

Property, Plant and Equipment (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property plant and equipment gross	$ 1,354,277		$ 1,354,277		$ 1,436,463
Depreciation expense	17,600	$ 20,100	54,400	$ 56,900
Interest costs capitalized	700	$ 500	2,200	$ 2,000
FERC Regulated Assets
Property, Plant and Equipment [Line Items]
Property plant and equipment gross	$ 376,400		$ 376,400		$ 367,600

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets (Schedule of Goodwill) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Goodwill [Line Items]
Goodwill	$ 51,723	$ 128,866
Liquid Pipelines and Services
Goodwill [Line Items]
Goodwill	35,708	35,708
Terminalling Services
Goodwill [Line Items]
Goodwill	11,043	88,466
Offshore Pipelines and Services
Goodwill [Line Items]
Goodwill	$ 4,972	$ 4,692

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets Schedule of Intangible Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 215,129	$ 260,868
Accumulated Amortization	(78,592)	(86,858)
Net Carrying Amount	136,537	174,010
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	64,745	110,483
Accumulated Amortization	(16,290)	(29,965)
Net Carrying Amount	48,455	80,518
Customer contracts
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	94,693	94,692
Accumulated Amortization	(51,910)	(48,173)
Net Carrying Amount	42,783	46,519
Dedicated acreage
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	42,546	42,547
Accumulated Amortization	(7,248)	(6,216)
Net Carrying Amount	35,298	36,331
Collaborative arrangements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	11,884	11,884
Accumulated Amortization	(2,051)	(1,415)
Net Carrying Amount	9,833	10,469
Noncompete agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,064	1,064
Accumulated Amortization	(1,064)	(1,064)
Net Carrying Amount	0	0
Other
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	197	198
Accumulated Amortization	(29)	(25)
Net Carrying Amount	$ 168	$ 173

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets Goodwill and Intangible Assets (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 2.5	$ 6.4	$ 7.8	$ 20.6
Remainder of 2018	2.5		2.5
2,019	10.2		10.2
2,020	10.2		10.2
2,021	10.2		10.2
2,022	$ 9.3		$ 9.3
Minimum
Finite-Lived Intangible Assets [Line Items]
Finite-Lived intangible asset, useful life			5 years
Maximum
Finite-Lived Intangible Assets [Line Items]
Finite-Lived intangible asset, useful life			30 years

Investment in Unconsolidated _3

Investment in Unconsolidated Affiliates Partnership's Equity Investments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Balances			$ 348,434
Earnings in unconsolidated affiliates	$ 24,622	$ 16,827	47,742	$ 49,781
Contributions			4,873
Distributions			(64,260)
Balances	$ 336,789		$ 336,789
FPS
Schedule of Equity Method Investments [Line Items]
Ownership interest (percent)	35.70%		35.70%		35.70%
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Balances			$ 90,412
Earnings in unconsolidated affiliates			14,892
Contributions			847
Distributions			(11,256)
Balances	$ 94,895		$ 94,895
OGL
Schedule of Equity Method Investments [Line Items]
Ownership interest (percent)	35.70%		35.70%		35.70%
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Balances			$ 46,932
Earnings in unconsolidated affiliates			8,204
Contributions			6
Distributions			(12,076)
Balances	$ 43,066		$ 43,066
Destin
Schedule of Equity Method Investments [Line Items]
Ownership interest (percent)	66.70%		66.70%		66.70%
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Balances			$ 124,245
Earnings in unconsolidated affiliates			8,543
Contributions			0
Distributions			(21,980)
Balances	$ 110,808		$ 110,808
Tri-State
Schedule of Equity Method Investments [Line Items]
Ownership interest (percent)	16.70%		16.70%		16.70%
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Balances			$ 53,057
Earnings in unconsolidated affiliates			2,983
Contributions			0
Distributions			(4,701)
Balances	$ 51,339		$ 51,339
Okeanos
Schedule of Equity Method Investments [Line Items]
Ownership interest (percent)	66.70%		66.70%		66.70%
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Balances			$ 22,445
Earnings in unconsolidated affiliates			8,225
Contributions			0
Distributions			(11,499)
Balances	$ 19,171		$ 19,171
Wilprise
Schedule of Equity Method Investments [Line Items]
Ownership interest (percent)	25.30%		25.30%		25.30%
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Balances			$ 4,689
Earnings in unconsolidated affiliates			664
Contributions			0
Distributions			(848)
Balances	$ 4,505		$ 4,505
Cayenne JV
Schedule of Equity Method Investments [Line Items]
Ownership interest (percent)	50.00%		50.00%		50.00%
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Balances			$ 6,654
Earnings in unconsolidated affiliates			4,231
Contributions			4,020
Distributions			(1,900)
Balances	$ 13,005		$ 13,005

Investment in Unconsolidated _4

Investment in Unconsolidated Affiliates Financial Information for the Partnership's Equity Investments - Balance Sheets (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Equity Method Investments and Joint Ventures [Abstract]
Current assets	$ 88,702	$ 80,405
Non-current assets	1,257,275	1,288,862
Current liabilities	86,821	130,904
Non-current liabilities	$ 470,391	$ 436,584

Investment in Unconsolidated _5

Investment in Unconsolidated Affiliates Financial Information for the Partnership's Equity Investments - Statement of Operations (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Aug. 31, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Equity Method Investments and Joint Ventures [Abstract]
Revenue		$ 85,504	$ 105,621	$ 194,193	$ 308,987
Operating expenses		6,665	24,168	21,172	76,145
Net income		$ 63,078	$ 76,650	$ 123,226	$ 220,617
POGS
Schedule of Equity Method Investments [Line Items]
Percent interest acquired (percent)	100.00%

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Other Liabilities Disclosure [Abstract]
Capital expenditures	$ 9,069	$ 10,721
Accrued interest	14,290	3,190
Convertible preferred unit distributions	8,354	0
Current portion of asset retirement obligation	3,764	6,416
Additional Blackwater acquisition consideration (see Note 19)	5,000	5,000
Taxes payable	42,350	5,263
Due to related parties	9,508	6,609
Royalties, gas imbalance and leases payables	5,734	7,905
Professional fees	4,587	1,848
Other	13,485	21,902
Total accrued expenses and other current liabilities	$ 116,141	$ 68,854

Asset Retirement Obligations (D

Asset Retirement Obligations (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Current portion	$ 6,416
Non-current asset retirement obligation	66,194
Balances at December 31, 2017	72,610
Additions	260
Revision in estimate	(216)
Disposals	(516)
Expenditures	(3,149)
Accretion expense	2,865
Balances at September 30, 2018	72,610	$ 71,854
Current portion	(3,764)
Non-current asset retirement obligation	$ 68,090
Restricted cash and cash equivalents		$ 5,000

Debt Obligations (Details)

Debt Obligations (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Long-term	$ 1,113,240	$ 1,218,238
Unamortized debt issuance costs	(8,519)	(9,231)
Total debt obligations	1,104,721	1,209,007
Less: current portion	(603,502)	(7,551)
Long-term debt	$ 501,219	1,201,456
Senior Notes | 8.50% Senior Notes
Debt Instrument [Line Items]
Debt instrument, stated interest rate (percent)	8.50%
Long-term	$ 425,000	425,000
Senior Notes | 3.77% Senior Notes
Debt Instrument [Line Items]
Debt instrument, stated interest rate (percent)	3.77%
Long-term	$ 57,531	58,324
Senior Notes | 3.97% Trans-Union Secured Senior notes
Debt Instrument [Line Items]
Debt instrument, stated interest rate (percent)	3.97%
Long-term	$ 30,709	32,025
Other debt
Debt Instrument [Line Items]
Long-term	0	4,989
Revolving Credit Facility
Debt Instrument [Line Items]
Revolving credit facility	$ 600,000	$ 697,900

Debt Obligations (Narrative) (D

Debt Obligations (Narrative) (Details)	Jul. 31, 2018USD ($)	Jun. 29, 2018	Sep. 30, 2018USD ($)	Sep. 30, 2017
Amendment to Original Credit Agreement
Debt Instrument [Line Items]
Percentage of net cash proceeds from sale (percent)			100.00%
Required prepayment, cash proceeds threshold for undefined disposal			$ 5,000,000
Reduction of borrowing capacity upon disposal			200,000,000
Borrowing capacity under Credit Agreement			$ 700,000,000
Reduction of borrowing capacity upon disposal, percentage of cash proceeds of disposal			50.00%
Reduction of borrowing capacity, threshold for undefined disposition			$ 15,000,000
Reduction of borrowing capacity, percentage of cash proceeds of undefined disposal			25.00%
Borrowings outstanding			$ 600,000,000
Letters of credit outstanding, amount			39,000,000
Available borrowing capacity			61,000,000
Remaining borrowing capacity currently available			$ 41,000,000
Weighted average interest rate on borrowings under facility			6.23%	4.85%
Amendment to Original Credit Agreement | Maximum
Debt Instrument [Line Items]
Consolidated Total Leverage Ratio		5
Amendment to Original Credit Agreement | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate		3.50%
8.50% Senior Notes | Senior Notes
Debt Instrument [Line Items]
Debt instrument, stated interest rate (percent)			8.50%
Not Discontinued Operations | Marine Liquids Terminals
Debt Instrument [Line Items]
Proceeds from sale of business and assets, net of cash on hand	$ 208,600,000
Advisory fees and other transaction costs	$ 5,700,000

Debt Obligations (Financial Cov

Debt Obligations (Financial Covenants) (Details)	9 Months Ended
	Sep. 30, 2018
Amendment to Original Credit Agreement | Maximum
Debt Instrument [Line Items]
Ratio of indebtedness to net capital, after allowed acquisition	5.50
Revolving Credit Facility
Debt Instrument [Line Items]
Minimum Consolidated Interest Coverage Ration, Actual	2.37
Maximum Allowable Consolidated Total Leverage Ratio, Actual	5.65
Maximum Allowable Consolidated Secured Leverage Ratio, Actual	3.31
June 30, 2018 | Revolving Credit Facility
Debt Instrument [Line Items]
Consolidated Interest Coverage Ratio	2.50
Consolidated Secured Leverage Ratio	6.15
Consolidated Total Leverage Ratio	4
September 30, 2018 | Revolving Credit Facility
Debt Instrument [Line Items]
Consolidated Interest Coverage Ratio	2
Consolidated Secured Leverage Ratio	6.25
Consolidated Total Leverage Ratio	3.75
December 31, 2018 | Revolving Credit Facility
Debt Instrument [Line Items]
Consolidated Interest Coverage Ratio	1.75
Consolidated Secured Leverage Ratio	5.50
Consolidated Total Leverage Ratio	3.50
March 31, 2019 | Revolving Credit Facility
Debt Instrument [Line Items]
Consolidated Interest Coverage Ratio	1.75
Consolidated Secured Leverage Ratio	5
Consolidated Total Leverage Ratio	3.50
June 30, 2019 and thereafter | Revolving Credit Facility
Debt Instrument [Line Items]
Consolidated Interest Coverage Ratio	2
Consolidated Secured Leverage Ratio	5
Consolidated Total Leverage Ratio	3.50

Debt Obligation, Redemption Pri

Debt Obligation, Redemption Prices (Details) - Senior Notes - 8.50% Senior Notes	9 Months Ended
	Sep. 30, 2018
2,018
Debt Instrument [Line Items]
Redemption price (percent)	104.25%
2,019
Debt Instrument [Line Items]
Redemption price (percent)	102.125%
2020 and thereafter
Debt Instrument [Line Items]
Redemption price (percent)	100.00%

Convertible Preferred Units (Sc

Convertible Preferred Units (Schedule of Convertible Preferred Units) (Details) - USD ($) shares in Thousands, $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Increase (Decrease) in Partners' Capital [Roll Forward]
Convertible preferred units, Beginning Balance, Amount,	$ 317,180
Paid in kind unit distributions, Amount	74,772	$ 94,120
Convertible preferred units, Ending Balance, Amount,	317,180
Unit Distributions
Increase (Decrease) in Partners' Capital [Roll Forward]
Paid in kind unit distributions, Amount	$ 0
Series A
Increase (Decrease) in Partners' Capital [Roll Forward]
Convertible preferred units, Beginning Balance, Units	10,719
Convertible preferred units, Ending Balance, Units	11,010
Convertible preferred units, Beginning Balance, Amount,	$ 191,798
Convertible preferred units, Ending Balance, Amount,	$ 191,798
Series A | Unit Distributions
Increase (Decrease) in Partners' Capital [Roll Forward]
Paid in kind unit distributions, Units	291
Paid in kind unit distributions, Amount	$ 0
Series C
Increase (Decrease) in Partners' Capital [Roll Forward]
Convertible preferred units, Beginning Balance, Units	8,965
Convertible preferred units, Ending Balance, Units	9,242
Convertible preferred units, Beginning Balance, Amount,	$ 125,382
Convertible preferred units, Ending Balance, Amount,	$ 125,382
Series C | Unit Distributions
Increase (Decrease) in Partners' Capital [Roll Forward]
Paid in kind unit distributions, Units	277
Paid in kind unit distributions, Amount	$ 0

Convertible Preferred Units (De

Convertible Preferred Units (Details)	Apr. 25, 2016$ / sharesshares	Jul. 27, 2015USD ($)$ / shares	Apr. 15, 2013USD ($)$ / sharesshares	Sep. 30, 2018USD ($)$ / sharesshares	Dec. 31, 2015USD ($)shares	Dec. 31, 2017shares
Series A
Preferred Units [Line Items]
Sale of units percentage			90.00%
Convertible preferred units (shares) | shares			5,142,857	11,010,000		10,719,000
Distribution per unit			$ 0.4125
Conversion price (usd per share)				$ 15.10
Conversion ratio				1.1589
Series A | High Point Infrastructure Partners, LLC
Preferred Units [Line Items]
Issuance of units | $			$ 15,000,000
Series A-2
Preferred Units [Line Items]
Conversion price (usd per share)				$ 15.10
Conversion ratio				1.1589
Aggregate proceeds | $					$ 45,000,000
Investment options, exercise price (in usd per share)		$ 17.50
Call right defined acquisition value | $		$ 100,000,000
Series A-2 | Magnolia Infrastructure Partners, LLC | Issuance of Preferred Units
Preferred Units [Line Items]
Units issued (in shares) | shares					2,571,430
Series C
Preferred Units [Line Items]
Convertible preferred units (shares) | shares				9,242,000		8,965,000
Conversion price (usd per share)				$ 13.27
Conversion ratio				1.0550
Investment options, exercise price (in usd per share)	$ 14
Shares issued upon conversion (in shares) | shares	1
Class of warrant, number of securities called by warrants (in shares) | shares	800,000
Class of warrant, exercise price of warrants (in usd per share)	$ 7.25
Warrant, exercisable period	7 years
Fair value of warrant unit (in usd per share)				$ 4.41
Warrants and Rights Outstanding, Term				7 years
Issuance of warrant | $				$ 4,500,000
Series C | ArcLight | Issuance of Preferred Units
Preferred Units [Line Items]
Units issued (in shares) | shares	8,571,429
Dividend yield | Series C
Preferred Units [Line Items]
Fair value measurement significant assumptions (percent)				0.18
Common unit volatility | Series C
Preferred Units [Line Items]
Fair value measurement significant assumptions (percent)				0.42

Partners Capital (Narrative) (D

Partners Capital (Narrative) (Details) $ / shares in Units, $ in Millions	Oct. 25, 2018$ / shares	Sep. 30, 2018$ / sharesshares	Sep. 30, 2017$ / sharesshares	Sep. 30, 2018USD ($)$ / sharesshares	Sep. 30, 2017USD ($)$ / sharesshares	Dec. 31, 2017shares
Class of Stock [Line Items]
General partner interest				1.30%
Limited partner interests				98.70%
General partner interest, period distribution amount | $				$ 0.1	$ 3.9
General partner interests, units issued (in shares) | shares		981,000		981,000		965,000
Distribution declared per common unit (in usd per share)		$ 0.1031	$ 0.4125	$ 0.6187	$ 1.2375
Subsequent Event
Class of Stock [Line Items]
Distribution declared per common unit (in usd per share)	$ 0.1031
Minimum
Class of Stock [Line Items]
Fair value input, option value (in usd per share)				0.31
Maximum
Class of Stock [Line Items]
Fair value input, option value (in usd per share)				2.05
Series A
Class of Stock [Line Items]
Minimum cumulative distributions obligated to pay each quarter (dollars per unit)				$ 0.4125
General Partner
Class of Stock [Line Items]
General partner interests, units issued (in shares) | shares		16,326	272,811	16,326	272,811
Discount rate | Minimum
Class of Stock [Line Items]
Fair value measurement significant assumptions (percent)		0.0580		0.0580
Discount rate | Maximum
Class of Stock [Line Items]
Fair value measurement significant assumptions (percent)		0.0623		0.0623
Assumed growth rate | Maximum
Class of Stock [Line Items]
Fair value measurement significant assumptions (percent)		0.010		0.010

Partners_ Capital Outstanding U

Partners’ Capital Outstanding Units (Details) - shares shares in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Increase (Decrease) in Partners' Capital [Roll Forward]
Balances at December 31, 2017	965
Balances at December 31, 2017	52,711
Balances at September 30, 2018	981
Balances at September 30, 2018	52,990
General Partner | LTIP
Increase (Decrease) in Partners' Capital [Roll Forward]
Partners' Capital Account Increase	0
General Partner | GP Units
Increase (Decrease) in Partners' Capital [Roll Forward]
Partners' Capital Account Increase		16
Limited Partner | LTIP
Increase (Decrease) in Partners' Capital [Roll Forward]
Partners' Capital Account Increase	279
Limited Partner | GP Units
Increase (Decrease) in Partners' Capital [Roll Forward]
Partners' Capital Account Increase		0

Partners' Capital (Distribution

Partners' Capital (Distributions Declared and Paid) (Details) - USD ($) $ / shares in Units, $ in Thousands	Aug. 14, 2018	May 15, 2018	Feb. 14, 2018
Distribution Made to Limited Partner [Line Items]
Cash Distributions	$ 5,535	$ 22,140	$ 22,035
Cash Distributions Per Common Unit (dollars per unit)	$ 0.1031	$ 0.4125	$ 0.4125
General Partner
Distribution Made to Limited Partner [Line Items]
Cash Distributions	$ 72	$ 287	$ 290
Limited Partner
Distribution Made to Limited Partner [Line Items]
Cash Distributions	$ 5,463	$ 21,853	$ 21,745

Partners_ Capital Distributions

Partners’ Capital Distributions (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Class of Stock [Line Items]
General Partner's distribution			$ 74,772	$ 94,120
Limited Partner
Class of Stock [Line Items]
General Partner's distribution			73,794	93,144
General Partner
Class of Stock [Line Items]
General Partner's distribution			978	976
Cash Paid
Class of Stock [Line Items]
General Partner's distribution	$ 13,889	$ 28,357	66,418	88,851
Cash Paid | Limited Partner
Class of Stock [Line Items]
General Partner's distribution	5,463	21,345	49,061	67,648
Distributions declared	5,500	21,700
Cash Paid | General Partner
Class of Stock [Line Items]
General Partner's distribution	72	277	649	645
Distributions declared	100	300
Accrued
Class of Stock [Line Items]
General Partner's distribution	8,354	8,255	8,354	8,255
Paid-in-kind units
Class of Stock [Line Items]
General Partner's distribution	0	1,924	8,076	6,838
Series A | Cash Paid
Class of Stock [Line Items]
General Partner's distribution	4,542	2,145	9,084	6,790
Series A | Accrued
Class of Stock [Line Items]
General Partner's distribution	4,542	4,105	4,542	4,105
Series A | Paid-in-kind units
Class of Stock [Line Items]
General Partner's distribution	0	1,924	3,767	6,838
Series C | Cash Paid
Class of Stock [Line Items]
General Partner's distribution	3,812	3,627	7,624	10,880
Series C | Accrued
Class of Stock [Line Items]
General Partner's distribution	3,812	4,150	3,812	4,150
Series C | Paid-in-kind units
Class of Stock [Line Items]
General Partner's distribution	0	0	4,309	0
Series D | Cash Paid
Class of Stock [Line Items]
General Partner's distribution	$ 0	$ 963	$ 0	$ 2,888

Net Income (Loss) per Limited_3

Net Income (Loss) per Limited Partner Unit (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Income from continuing operations	$ 38,183	$ 11,806	$ 7,067	$ (42,266)
Net income attributable to noncontrolling interests	(25)	(621)	(83)	(3,386)
Net income (loss) from continuing operations attributable to the Partnership	38,158	11,185	6,984	(45,652)
General Partner's distribution			74,772	94,120
General Partner's share in undistributed (loss) income	(303)	210	683	1,729
Income (loss) from continuing operations attributable to Limited Partners	29,428	2,853	(17,830)	(70,486)
Income from discontinued operations, net of tax	0	44,696	0	42,185
Net income (loss) attributable to Limited Partners	$ 29,428	$ 47,549	$ (17,830)	$ (28,301)
Weighted average number of common units outstanding: basic (shares)	52,984	52,021	52,917	52,021
Potentially dilutive common unit equivalents (shares)	22,541	0	0	0
Weighted average number of common units outstanding: diluted (shares)	75,525	52,021	52,917	52,021
Limited Partners' net income (loss) per common unit - Basic and Diluted
Income (loss) from continuing operations (in usd per share)	$ 0.56	$ 0.05	$ (0.34)	$ (1.35)
Income (loss) from discontinued operations (in usd per share)	0	0.86	0	0.81
Net income (loss) per common unit (in usd per share)	0.56	0.91	(0.34)	(0.54)
Income (loss) from continuing operations (in usd per share)	0.39	0.05	(0.34)	(1.35)
Income (loss) from discontinued operations (in usd per share)	0	0.86	0	0.81
Net income (loss) per common unit (in usd per share)	$ 0.39	$ 0.91	$ (0.34)	$ (0.54)
Potential common unit equivalents excluded from determination of diluted limited partners' net loss per common unit (in shares)		24,900	23,400	24,800
Series A
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Distributions	$ (4,542)	$ (4,105)	$ (13,626)	$ (12,472)
Series C
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Distributions	(3,812)	(4,150)	(11,437)	(11,403)
Series D
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Distributions	0	0	0	(1,925)
General Partner
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
General Partner's distribution			978	976
General Partner | Accrued
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
General Partner's distribution	$ (73)	$ (287)	$ (434)	$ (763)

Incentive Compensation (Narrati

Incentive Compensation (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 02, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense - options	$ 100,000		$ 100,000
Employer matching	$ 600,000	$ 1,800,000	$ 500,000	$ 1,400,000
LTIP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common units available for future grants (shares)	3,763,750		3,763,750
Options granted (in shares)			0
LTIP | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)			818,357
Granted (in usd per share)			$ 8.54
Vested (in shares)			351,166
Vested (in usd per share)			$ 6.26
Forfeited (in shares)			356,479
Forfeited (in usd per share)			$ 6.62
Unrecognized compensation expense - other than options	$ 8,600,000		$ 8,600,000
LTIP | Performance-based Awards (PSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)			0
Unrecognized compensation expense - other than options	4,900,000		$ 4,900,000
Cash Retention Plan | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cash award to be earned per phantom unit					$ 6
Expense associated with award recognized in period	$ 900,000

Incentive Compensation (Compone

Incentive Compensation (Components of Equity-Based Compensation Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity compensation expense			$ 3,529	$ 6,067
LTIP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity compensation expense	$ 1,335	$ 834	3,529	6,067
LTIP | RSU
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity compensation expense	1,083	815	2,616	6,010
LTIP | PSU
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity compensation expense	237	0	867	0
LTIP | Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity compensation expense	$ 15	$ 19	$ 46	$ 57

Related Party Transactions (Na

Related Party Transactions (Narrative) (Details) - USD ($)	1 Months Ended	3 Months Ended	9 Months Ended
	Aug. 31, 2018	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 28, 2018	Dec. 31, 2017	Dec. 31, 2013
Related Party Transaction [Line Items]
Contributions			$ 31,786,000	$ 38,270,000
Revenue from related parties				1,900,000
Due from related parties		$ 2,461,000	2,461,000			$ 4,362,000
Blackwater
Related Party Transaction [Line Items]
Additional consideration							$ 5,000,000
Additional Blackwater acquisition consideration		5,000,000	5,000,000
Republic Midstream, LLC (“Republic”)
Related Party Transaction [Line Items]
Monthly fee				100,000
Receivable balance from affiliate						800,000
Magnolia
Related Party Transaction [Line Items]
Partners' Capital Account, Exchanges and Conversions, Per Unit					$ 6.10
Proceeds from additional capital contribution	$ 8,300,000	9,400,000
General Partner
Related Party Transaction [Line Items]
Contributions			31,800,000
General Partner | Accrued expenses and other current liabilities
Related Party Transaction [Line Items]
Due to related party		7,900,000	7,900,000			6,500,000
Destin and Okeanos
Related Party Transaction [Line Items]
Revenue from related parties			1,900,000
Destin | Accrued expenses and other current liabilities
Related Party Transaction [Line Items]
Due to related party		600,000	600,000
Due from related parties						500,000
Okeanos | Accrued expenses and other current liabilities
Related Party Transaction [Line Items]
Due from related parties		100,000	100,000			$ 400,000
Consolidated Asset Management Services, LLC (CAMS) | Director
Related Party Transaction [Line Items]
Ownership interest (percent)						10.00%
Affiliated Entity | Consolidated Asset Management Services, LLC (CAMS)
Related Party Transaction [Line Items]
Receivable balance from affiliate		0	0			$ 0
Purchases from related party			200,000	200,000
Affiliated Entity | CIMA Energy Ltd
Related Party Transaction [Line Items]
Revenue from related parties			1,700,000	6,200,000
Purchases from related party			3,500,000	$ 3,700,000
AMID Merger GP II, LLC | Accrued expenses and other current liabilities
Related Party Transaction [Line Items]
Due from related parties		$ 1,100,000	$ 1,100,000			$ 2,500,000

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Limited Partners' Capital Account [Line Items]
Cash paid for interest	$ 49,294	$ 40,885
Increase (decrease) in accrued property, plant and equipment purchases	(1,652)	(15,112)
Accrued contributions to unconsolidated affiliates	(89)	0
Issuance of common units for the Panther acquisition	0	12,532
Contributions from an affiliate holding limited partner interests	31,786	42,270
Accrued distributions on convertible preferred units	8,354	8,255
Paid-in-kind distributions on convertible preferred units	8,076	6,838
Limited Partner
Limited Partners' Capital Account [Line Items]
Contributions from an affiliate holding limited partner interests	$ 0	$ 4,000

Reportable Segments (Details)

Reportable Segments (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)segments	Sep. 30, 2017USD ($)
Segment Reporting, Revenue Reconciling Item [Line Items]
Number of reportable segments | segments			5
Segment information
Revenue	$ 202,580	$ 162,887	$ 628,920	$ 488,431
Loss on commodity derivatives, net	(234)	(597)	(530)	(33)
Total revenue	202,346	162,290	628,390	488,398
Cost of Sales	150,274	112,398	461,948	342,886
Direct operating expenses	20,407	20,705	65,595	56,819
Corporate expenses	23,857	27,083	69,922	84,570
Termination fee	17,000	0	17,000	0
Depreciation, amortization and accretion	23,040	26,781	66,274	78,834
Gain on sale of assets, net	(99,396)	(4,061)	(99,491)	(4,064)
Total operating expenses	135,182	182,906	581,248	559,045
Operating income (loss)	67,164	(20,616)	47,142	(70,647)
Interest expense, net of capitalized interest	(22,267)	(17,759)	(55,834)	(51,037)
Other income (expense), net	(128)	34,085	62	32,248
Earnings in unconsolidated affiliates	24,622	16,827	47,742	49,781
Income (loss) from continuing operations before income taxes	69,391	12,537	39,112	(39,655)
Income tax expense	(31,208)	(731)	(32,045)	(2,611)
Income (loss) from continuing operations	38,183	11,806	7,067	(42,266)
Income from discontinued operations, including gain on sale	0	44,696	0	42,185
Net income (loss)	38,183	56,502	7,067	(81)
Net income attributable to noncontrolling interests	(25)	(621)	(83)	(3,386)
Net income (loss) attributable to the Partnership	38,158	55,881	6,984	(3,467)
Gas Gathering and Processing Services
Segment information
Revenue	53,429		138,613
Loss on commodity derivatives, net	(93)		(385)
Total revenue	53,336		138,228
Liquid Pipelines and Services
Segment information
Revenue	109,559		349,947
Loss on commodity derivatives, net	(141)		(145)
Total revenue	109,418		349,802
Natural Gas Transportation Services
Segment information
Revenue	12,710		44,339
Loss on commodity derivatives, net	0		0
Total revenue	12,710		44,339
Offshore Pipelines and Services
Segment information
Revenue	19,331		54,711
Loss on commodity derivatives, net	0		0
Total revenue	19,331		54,711
Terminalling Services
Segment information
Revenue	7,551		41,310
Loss on commodity derivatives, net	0		0
Total revenue	7,551		41,310
Operating Segments | Gas Gathering and Processing Services
Segment information
Revenue	53,429	37,287	138,613	111,001
Loss on commodity derivatives, net	(93)	(65)	(385)	(170)
Total revenue	53,336	37,222	138,228	110,831
Cost of Sales	37,917	24,492	95,921	74,261
Direct operating expenses	0		0	0
Total operating expenses
Operating income (loss)
Earnings in unconsolidated affiliates	0	0	0	0
Income (loss) from continuing operations before income taxes
Segment gross margin	15,421	12,761	42,613	36,663
Operating Segments | Liquid Pipelines and Services
Segment information
Revenue	109,559	87,022	349,947	253,590
Loss on commodity derivatives, net	(141)	(532)	(145)	137
Total revenue	109,418	86,490	349,802	253,727
Cost of Sales	103,345	80,510	333,342	236,896
Direct operating expenses	0		0	0
Total operating expenses
Operating income (loss)
Earnings in unconsolidated affiliates	3,172	1,317	7,878	3,886
Income (loss) from continuing operations before income taxes
Segment gross margin	9,351	7,808	24,365	21,209
Operating Segments | Natural Gas Transportation Services
Segment information
Revenue	12,710	11,131	44,339	34,966
Loss on commodity derivatives, net	0	0	0	0
Total revenue	12,710	11,131	44,339	34,966
Cost of Sales	5,502	5,692	16,628	17,630
Direct operating expenses	0		0	0
Total operating expenses
Operating income (loss)
Earnings in unconsolidated affiliates	0	0	0	0
Income (loss) from continuing operations before income taxes
Segment gross margin	7,044	5,356	27,384	17,106
Operating Segments | Offshore Pipelines and Services
Segment information
Revenue	19,331	14,360	54,711	41,330
Loss on commodity derivatives, net	0	0	0	0
Total revenue	19,331	14,360	54,711	41,330
Cost of Sales	1,959	558	6,105	6,487
Direct operating expenses	0		0	0
Total operating expenses
Operating income (loss)
Earnings in unconsolidated affiliates	21,450	15,510	39,864	45,895
Income (loss) from continuing operations before income taxes
Segment gross margin	38,823	29,312	88,470	80,738
Operating Segments | Terminalling Services
Segment information
Revenue	7,551	13,087	41,310	47,544
Loss on commodity derivatives, net	0	0	0	0
Total revenue	7,551	13,087	41,310	47,544
Cost of Sales	1,551	1,146	9,952	7,612
Direct operating expenses	2,152	3,432	10,605	9,503
Total operating expenses
Operating income (loss)
Earnings in unconsolidated affiliates	0	0	0	0
Income (loss) from continuing operations before income taxes
Segment gross margin	$ 3,848	$ 8,509	$ 20,753	$ 30,429

Reportable Segments - Assets (D

Reportable Segments - Assets (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Assets	$ 1,834,605		$ 1,834,605		$ 1,923,466
Investments in unconsolidated affiliates	336,789		336,789		348,434
Total capital expenditures	16,829	$ 19,992	73,342	$ 61,883
Gas Gathering and Processing Services
Segment Reporting Information [Line Items]
Assets	397,726		397,726		404,872
Total capital expenditures	11,603	4,788	24,914	13,315
Liquid Pipelines and Services
Segment Reporting Information [Line Items]
Assets	370,833		370,833		359,646
Investments in unconsolidated affiliates	68,849		68,849		64,399
Total capital expenditures	1,468	1,301	12,649	2,677
Natural Gas Transportation Services
Segment Reporting Information [Line Items]
Assets	267,185		267,185		268,991
Total capital expenditures	1,554	6,431	4,045	30,797
Offshore Pipelines and Services
Segment Reporting Information [Line Items]
Assets	525,493		525,493		553,213
Investments in unconsolidated affiliates	267,940		267,940		284,035
Total capital expenditures	155	2,283	20,491	3,417
Terminalling Services
Segment Reporting Information [Line Items]
Assets	187,779		187,779		293,085
Total capital expenditures	691	3,954	6,813	6,795
Other Segments
Segment Reporting Information [Line Items]
Assets	85,589		85,589		$ 43,659
Total capital expenditures	$ 1,358	1,235	$ 4,430	4,882
Propane Business
Segment Reporting Information [Line Items]
Total capital expenditures		$ 700		$ 3,100

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Millions	Oct. 25, 2018	Oct. 23, 2018	Sep. 25, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Subsequent Event [Line Items]
Distribution declared per common unit (in usd per share)				$ 0.1031	$ 0.4125	$ 0.6187	$ 1.2375
Subsequent Event
Subsequent Event [Line Items]
Distribution declared per common unit (in usd per share)	$ 0.1031
Distribution declared per common unit - annualized basis (in usd per share)	$ 0.4125
Ajax Settlement
Subsequent Event [Line Items]
Damages sought			$ 4.7
Accrued amount				$ 2		$ 2
Ajax Settlement | Subsequent Event
Subsequent Event [Line Items]
Payment made towards settlement		$ 2