Investments in Non-Controlled Entities (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Transportation and terminals revenue	$ 472,248	$ 433,239	$ 904,185	$ 825,910
Product sales revenue	166,797	182,004	408,389	427,624
Cost of product sales	153,679	145,975	353,271	318,851
Trade accounts receivable	106,679		106,679		$ 138,779
Other accounts receivable	21,922		21,922		14,561
Change in Equity Method Investments [Roll Forward]
Investments at December 31, 2017			1,082,511
Additional investment			144,859
Other Adjustment to Equity Investment			502
Proportionate share of earnings			78,251
Amortization of excess investment and capitalized interest			(1,203)
Earnings of non-controlled entities	42,510	25,576	77,048	47,022
Distributions of earnings from investments in non-controlled entities			94,661	57,906
Distributions in excess of earnings of non-controlled entities				0
Investments at June 30, 2018	1,210,259		1,210,259
Equity Method Investee [Member]
Schedule of Equity Method Investments [Line Items]
Related Party Transaction, Other Revenues from Transactions with Related Party	$ 1,200	1,400	$ 1,700	2,400
BridgeTex [Member]
Schedule of Equity Method Investments [Line Items]
Interest in equity method investment	50.00%		50.00%
BridgeTex [Member] | Equity Method Investee [Member]
Schedule of Equity Method Investments [Line Items]
Transportation and terminals revenue	$ 9,700	9,000	$ 19,600	17,900
Trade accounts receivable	200		200
Other accounts receivable	$ 100		$ 100
Double Eagle Pipeline Llc [Member]
Schedule of Equity Method Investments [Line Items]
Interest in equity method investment	50.00%		50.00%
Double Eagle Pipeline Llc [Member] | Equity Method Investee [Member]
Schedule of Equity Method Investments [Line Items]
Transportation and terminals revenue	$ 1,400	1,000	$ 2,900	1,800
Trade accounts receivable	$ 400		$ 400		500
HoustonLink Pipeline Company LLC [Member]
Schedule of Equity Method Investments [Line Items]
Interest in equity method investment	50.00%		50.00%
HoustonLink Pipeline Company LLC [Member] | Equity Method Investee [Member]
Schedule of Equity Method Investments [Line Items]
Accounts Payable, Other, Current					100
MVP Terminalling, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Interest in equity method investment	50.00%		50.00%
MVP Terminalling, LLC [Member] | Equity Method Investee [Member]
Schedule of Equity Method Investments [Line Items]
Other accounts receivable	$ 1,100		$ 1,100		400
Powder Springs Logistics, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Interest in equity method investment	50.00%		50.00%
Powder Springs Logistics, LLC [Member] | Equity Method Investee [Member]
Schedule of Equity Method Investments [Line Items]
Product sales revenue	$ 2,200	0	$ 4,900	0
Cost of product sales	400	0	400	0
Other accounts receivable	$ 2,100		$ 2,100		900
Powder Springs Logistics, LLC [Member] | Equity Method Investee [Member] | Guarantee of Indebtedness of Others [Member]
Schedule of Equity Method Investments [Line Items]
Interest in equity method investment	50.00%		50.00%
Guarantor Obligations, Maximum Exposure, Undiscounted	$ 25,000		$ 25,000
Guarantees, Fair Value Disclosure	$ 400		$ 400
Saddlehorn Pipeline Company [Member]
Schedule of Equity Method Investments [Line Items]
Interest in equity method investment	40.00%		40.00%
Saddlehorn Pipeline Company [Member] | Equity Method Investee [Member]
Schedule of Equity Method Investments [Line Items]
Transportation and terminals revenue	$ 600	$ 600	$ 1,100	$ 1,100
Other accounts receivable	$ 100		$ 100		100
Seabrook Logistics, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Interest in equity method investment	50.00%		50.00%
Seabrook Logistics, LLC [Member] | Equity Method Investee [Member]
Schedule of Equity Method Investments [Line Items]
Other accounts receivable	$ 400		$ 400		$ 200
Texas Frontera Llc [Member]
Schedule of Equity Method Investments [Line Items]
Interest in equity method investment	50.00%		50.00%