Organization, Description of Business And Basis Of Presentation (Policies)	3 Months Ended
	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation In the opinion of management, our accompanying consolidated financial statements which are unaudited, except for the consolidated balance sheet as of December 31, 2018, which is derived from our audited financial statements, include all normal and recurring adjustments necessary to present fairly our financial position as of March 31, 2019, the results of operations for the three months ended March 31, 2018 and 2019 and cash flows for the three months ended March 31, 2018 and 2019. The results of operations for the three months ended March 31, 2019 are not necessarily indicative of the results to be expected for the full year ending December 31, 2019 for several reasons. Profits from our butane blending activities are realized largely during the first and fourth quarters of each year. Additionally, gasoline demand, which drives transportation volumes and revenues on our refined products pipeline system, generally trends higher during the summer driving months. Further, the volatility of commodity prices impacts the profits from our commodity activities and, to a lesser extent, the volume of petroleum products we transport on our pipelines. Pursuant to the rules and regulations of the Securities and Exchange Commission, the financial statements in this report do not include all of the information and notes normally included with financial statements prepared in accordance with U.S. generally accepted accounting principles (“GAAP”). These financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2018.
Use of Estimates	Use of Estimates The preparation of our consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities that exist at the date of our consolidated financial statements, as well as their impact on the reported amounts of revenue and expense during the reporting periods. Actual results could differ from those estimates.
New Accounting Pronouncements	New Accounting Pronouncements - Adopted by us on January 1, 2019 In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-02, Leases (Topic 842). This ASU requires lessees to recognize a right of use asset and lease liability on the balance sheet for all leases, with the exception of short-term leases. The new accounting model for lessors remains largely the same, although some changes have been made to align it with the new lessee model and the new revenue recognition guidance. This update also requires companies to include additional disclosures regarding their lessee and lessor agreements. We adopted this standard on January 1, 2019, and it did not have a material impact on our consolidated statements of income or our leverage ratio as defined in our credit agreement. Adoption of this ASU resulted in an increase in our assets and liabilities by approximately $172 million due to the recognition of right of use assets and lease liabilities. See Note 7 – Leases for our lease disclosures.
Lease Policy, Lessee and Lessor	As of January 1, 2019, we adopted ASU 2016-02, Leases (Topic 842) using the modified retrospective method of adoption. We elected to use the transition option that allows us to initially apply the new lease standard at the adoption date and recognize a cumulative-effect adjustment (if any) to the opening balance of retained earnings in the year of adoption. Comparable periods continue to be presented under the guidance of the previous standard, ASC 840. ASC 842 requires lessees to recognize a lease liability and right-of-use asset on the balance sheet for operating leases. For lessors, the new accounting model remains largely the same, although some changes have been made to align it with the new lessee model and the new revenue recognition guidance, ASC 606, Revenue from Contracts with Customers. Our adoption of ASC 842 did not result in any material adjustments to retained earnings, changes in the timing or amounts of lease costs or changes to our leverage ratio as defined in our credit agreement. We have both lessee and lessor arrangements. Our leases are evaluated at inception or at any subsequent modification. Depending on the terms, leases are classified as either operating or finance leases if we are the lessee, or as operating, sales-type or direct financing leases if we are the lessor, as appropriate under ASC 842. Our lessee arrangements primarily include a terminalling and storage contract where we have exclusive use of dedicated tankage, leased pipelines and office buildings. Our lessor arrangements include pipeline capacity and storage contracts and our condensate splitter tolling agreement that qualify as operating leases under ASC 842. In addition, we have a long-term throughput and deficiency agreement with a customer that is being accounted for as a sales-type lease under ASC 842. In accordance with ASC 842, we have made an accounting policy election to not apply the new standard to lessee arrangements with a term of one year or less and no purchase option that is reasonably certain of exercise. We will continue to account for these short-term arrangements by recognizing payments and expenses as incurred, without recording a lease liability and right-of-use asset. We have also made an accounting policy election for both our lessee and lessor arrangements to combine lease and non-lease components. This election is applied to all of our lease arrangements as our non-lease components are not material and do not result in significant timing differences in the recognition of rental expenses or income.
Lessee, Leases	We recognize a lease liability for each lease based on the present value of remaining minimum fixed rental payments (which includes payments under any renewal option that we are reasonably certain to exercise), using a discount rate that approximates the rate of interest we would have to pay to borrow on a collateralized basis over a similar term. We also recognize a right-of-use asset for each lease, valued at the lease liability, adjusted for prepaid or accrued rent balances existing at the time of initial recognition. The lease liability and right-of-use asset are reduced over the term of the lease as payments are made and the assets are used. Related Party Operating Lease. In third quarter 2018, we entered into a long-term terminalling and storage contract with our equity investee, Seabrook, where we have exclusive use of dedicated tankage that is utilized to provide our customers with crude oil storage capacity and dock access for crude oil imports and exports on the Texas Gulf Coast. This arrangement meets the definition of an operating lease, and our lease liability includes renewal options necessary to maintain control of the assets for a time period sufficient to meet our performance obligations to our third-party customers. Minimum fixed rental payments are recognized on a straight-line basis over the life of the lease as costs and expenses on our consolidated statements of income. Variable and short-term rental payments are recognized as costs and expenses as they are incurred. Variable payments consist of amounts that exceed the contractual minimum rental payment (for example, incremental payment increases tied to a change in a market index).
Lessor, Leases	We recognize fixed rental income on a straight-line basis over the life of the lease as revenue on our consolidated statements of income. Variable rental payments are recognized as revenue in the period in which the changes in facts and circumstances on which the variable lease payments are based occur.