Investments in Non-Controlled Entities (Equity Method Investments) (Details) - USD ($) $ in Thousands			12 Months Ended
		Feb. 29, 2016	Dec. 31, 2017		Dec. 31, 2016	Dec. 31, 2015
Schedule of Equity Method Investments [Line Items]
Contribution of property, plant and equipment to a non-controlled entity			$ 97,638		$ 0	$ 13,252
Transportation and terminals revenue			1,731,775		1,591,119	1,544,746
Accounts Receivable, Net, Current			138,779		105,689
Other accounts receivable			14,561		25,761
Cost of product sales			635,617		493,338	447,273
Intangible Assets, Net (Excluding Goodwill)			$ 52,764		51,976
Finite-Lived Intangible Asset, Useful Life			21 years
Gain on exchange of interest in non-controlled entity			$ 0		(28,144)	0
Change in Equity Method Investments [Roll Forward]
Investments at December 31, 2016			931,255		765,628
Additional Investments	[1]		232,404
Proportionate Share of Equity Earnings			123,373
Amortization of Excess Investment and Capitalized Interest			(2,379)
Income (Loss) from Equity Method Investments			120,994		78,696	66,483
Distributions from investments in non-controlled entities			123,660		78,723	66,285
Distributions in excess of earnings of non-controlled entities			78,482	[2]	9,264	14,155
Investments at December 31, 2017			1,082,511		931,255	765,628
Equity Method Investment, Summarized Financial Information, Current Assets			229,342		208,901
Equity Method Investment, Summarized Financial Information, Noncurrent Assets			2,057,892		1,714,920
Equity Method Investment, Summarized Financial Information, Assets			2,287,234		1,923,821
Equity Method Investment, Summarized Financial Information, Current Liabilities			122,198		111,164
Equity Method Investment, Summarized Financial Information, Noncurrent Liabilities			74,533		27,022
Equity Method Investment, Summarized Financial Information, Liabilities			196,731		138,186
Equity Method Investment Summarized Financial Information, Equity			2,090,503		1,785,635
Equity Method Investment, Summarized Financial Information, Revenue			419,214		279,180	246,841
Equity Method Investment, Summarized Financial Information, Net Income (Loss)			256,423		164,684	138,457
Equity Method Investee [Member]
Schedule of Equity Method Investments [Line Items]
Related Party Transaction, Other Revenues from Transactions with Related Party			$ 3,600		4,200	1,300
BridgeTex [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage			50.00%
Change in Equity Method Investments [Roll Forward]
Distributions in excess of earnings of non-controlled entities			$ 6,200
BridgeTex [Member] | Equity Method Investee [Member]
Schedule of Equity Method Investments [Line Items]
Transportation and terminals revenue			36,100		35,500	34,600
Cost of product sales			14,500
Related Party Transaction, Purchases from Related Party			$ 6,700
Double Eagle Pipeline Llc [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage			50.00%
Double Eagle Pipeline Llc [Member] | Equity Method Investee [Member]
Schedule of Equity Method Investments [Line Items]
Transportation and terminals revenue			$ 4,700		3,300	3,400
Accounts Receivable, Net, Current			$ 500		300
HoustonLink Pipeline Company LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage			50.00%
HoustonLink Pipeline Company LLC [Member] | Equity Method Investee [Member]
Schedule of Equity Method Investments [Line Items]
Accounts Payable, Other			$ 100		0
MVP Terminalling, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage			50.00%
Joint Venture, Ownership Interest			50.00%
Contribution of property, plant and equipment to a non-controlled entity			$ 97,600
Change in Equity Method Investments [Roll Forward]
Distributions in excess of earnings of non-controlled entities			48,800
MVP Terminalling, LLC [Member] | Equity Method Investee [Member]
Schedule of Equity Method Investments [Line Items]
Other accounts receivable			$ 400		0
Powder Springs Logistics, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage			50.00%
Powder Springs Logistics, LLC [Member] | Equity Method Investee [Member]
Schedule of Equity Method Investments [Line Items]
Other accounts receivable			$ 900		0
Saddlehorn Pipeline Company [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage			40.00%
Saddlehorn Pipeline Company [Member] | Equity Method Investee [Member]
Schedule of Equity Method Investments [Line Items]
Transportation and terminals revenue			$ 2,100		700	$ 0
Other accounts receivable			$ 100		100
Seabrook Logistics, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage			50.00%
Seabrook Logistics, LLC [Member] | Equity Method Investee [Member]
Schedule of Equity Method Investments [Line Items]
Other accounts receivable			$ 200		0
Texas Frontera Llc [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage			50.00%
Osage Pipeline Co [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage		50.00%
Intangible Assets, Net (Excluding Goodwill)		$ 43,700
Nontrade Receivables		$ 8,300
Finite-Lived Intangible Asset, Useful Life		20 years
Gain on exchange of interest in non-controlled entity					$ (28,100)
Guarantee of Indebtedness of Others [Member] | Powder Springs Logistics, LLC [Member] | Equity Method Investee [Member]
Schedule of Equity Method Investments [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted			$ 50,000
Guarantees, Fair Value Disclosure			$ 800

[1] Includes our $97.6 million contribution of PP&E to MVP.

[2] Includes the $48.8 million distribution to us from MVP as reimbursement for the PP&E we contributed, as well as an additional distribution of $6.2 million from BridgeTex that is not related to the ongoing operations of non-controlled entities.