Investments in Non-Controlled Entities (Details) - USD ($) $ in Thousands		3 Months Ended			6 Months Ended
	Feb. 29, 2016	Jun. 30, 2016	Mar. 31, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Schedule of Equity Method Investments [Line Items]
Intangible Assets, Net (Excluding Goodwill)		$ 52,337			$ 52,337		$ 1,856
Equity Method Investment, Realized Gain (Loss) on Disposal		1,244		$ 0	28,144	$ 0
Change in Equity Method Investments [Roll Forward]
Investments at December 31, 2015			$ 765,628		765,628
Additional investment					109,933
Exchange of investment in non-controlled entity					(25,105)
Proportionate share of earnings					34,124
Amortization of excess investment and capitalized interest					(1,157)
Earnings of non-controlled entities		15,339		24,542	32,967	34,132
Distributions of earnings from investments in non-controlled entities					31,080	31,243
Distributions in excess of earnings of non-controlled entities					1,942	0
Investments at March 31, 2016		850,401			850,401
Equity Method Investment, Summarized Financial Information, Revenue		58,446		73,256	120,653	119,912
Equity Method Investment, Summarized Financial Information, Net Income (Loss)		$ 31,711		50,412	$ 68,225	71,030
BridgeTex [Member]
Schedule of Equity Method Investments [Line Items]
Interest in equity method investment		50.00%			50.00%
Change in Equity Method Investments [Roll Forward]
Investments at December 31, 2015			495,267		$ 495,267
Additional investment					7,003
Exchange of investment in non-controlled entity					0
Proportionate share of earnings					29,234
Amortization of excess investment and capitalized interest					(1,019)
Earnings of non-controlled entities					28,215
Distributions of earnings from investments in non-controlled entities					28,215
Distributions in excess of earnings of non-controlled entities					899
Investments at March 31, 2016		$ 501,371			501,371
Equity Method Investment, Summarized Financial Information, Revenue		48,426		61,629	99,224	98,765
Equity Method Investment, Summarized Financial Information, Net Income (Loss)		$ 27,219		45,619	$ 58,467	63,656
Double Eagle Pipeline Llc [Member]
Schedule of Equity Method Investments [Line Items]
Interest in equity method investment		50.00%			50.00%
HoustonLink Pipeline Company LLC [Member]
Schedule of Equity Method Investments [Line Items]
Interest in equity method investment		50.00%			50.00%
Powder Springs Logistics, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Interest in equity method investment		50.00%			50.00%
Saddlehorn Pipeline Company [Member]
Schedule of Equity Method Investments [Line Items]
Interest in equity method investment		40.00%			40.00%
Seabrook Logistics, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Interest in equity method investment		50.00%			50.00%
Texas Frontera Llc [Member]
Schedule of Equity Method Investments [Line Items]
Interest in equity method investment		50.00%			50.00%
Osage Pipeline Co [Member]
Schedule of Equity Method Investments [Line Items]
Interest in equity method investment	50.00%
Intangible Assets, Net (Excluding Goodwill)	$ 43,700
Nontrade Receivables	$ 8,300
Finite-Lived Intangible Asset, Useful Life	20 years
Equity Method Investment, Realized Gain (Loss) on Disposal		$ 1,200	26,900		$ 28,100
All Other Equity Investments [Member]
Change in Equity Method Investments [Roll Forward]
Investments at December 31, 2015			$ 270,361		270,361
Additional investment					102,930
Exchange of investment in non-controlled entity					(25,105)
Proportionate share of earnings					4,890
Amortization of excess investment and capitalized interest					(138)
Earnings of non-controlled entities					4,752
Distributions of earnings from investments in non-controlled entities					2,865
Distributions in excess of earnings of non-controlled entities					1,043
Investments at March 31, 2016		349,030			349,030
Equity Method Investment, Summarized Financial Information, Revenue		10,020		11,627	21,429	21,147
Equity Method Investment, Summarized Financial Information, Net Income (Loss)		4,492		4,793	9,758	7,374
Equity Method Investee [Member] | BridgeTex [Member]
Schedule of Equity Method Investments [Line Items]
Related Party Transaction, Other Revenues from Transactions with Related Party		8,800		8,500	17,700	16,900
Equity Method Investee [Member] | Double Eagle Pipeline Llc [Member]
Schedule of Equity Method Investments [Line Items]
Related Party Transaction, Other Revenues from Transactions with Related Party		900		$ 900	1,600	$ 1,800
Accounts Receivable, Related Parties, Current		400			400		$ 200
Equity Method Investee [Member] | HoustonLink Pipeline Company LLC [Member]
Schedule of Equity Method Investments [Line Items]
Related Party Transaction, Other Revenues from Transactions with Related Party		100			100
Equity Method Investee [Member] | Powder Springs Logistics, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Related Party Transaction, Other Revenues from Transactions with Related Party		100			100
Equity Method Investee [Member] | Saddlehorn Pipeline Company [Member]
Schedule of Equity Method Investments [Line Items]
Related Party Transaction, Other Revenues from Transactions with Related Party		800			1,200
Equity Method Investee [Member] | Seabrook Logistics, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Related Party Transaction, Other Revenues from Transactions with Related Party		$ 100			$ 100