Investments in Non-Controlled Entities (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Feb. 29, 2016	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Schedule of Equity Method Investments [Line Items]
Intangible Assets, Net (Excluding Goodwill)		$ 52,102		$ 52,102		$ 1,856
Equity Method Investment, Realized Gain (Loss) on Disposal		0	$ 0	28,144	$ 0
Change in Equity Method Investments [Roll Forward]
Investments at December 31, 2015				765,628
Additional investment				174,900
Exchange of investment in non-controlled entity				(25,105)
Proportionate share of earnings				53,246
Amortization of excess investment and capitalized interest				(1,703)
Earnings of non-controlled entities		18,576	15,521	51,543	49,653
Distributions of earnings from investments in non-controlled entities				50,047	47,236
Distributions in excess of earnings of non-controlled entities				4,500	9,341
Investments at September 30, 2016		912,419		912,419
Equity Method Investment, Summarized Financial Information, Revenue		69,865	60,085	190,518	179,997
Equity Method Investment, Summarized Financial Information, Net Income (Loss)		$ 38,663	32,301	$ 106,888	103,331
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
Additional investment				31,503
Exchange of investment in non-controlled entity				0
Proportionate share of earnings				45,990
Amortization of excess investment and capitalized interest				(1,529)
Earnings of non-controlled entities				44,461
Distributions of earnings from investments in non-controlled entities				44,461
Distributions in excess of earnings of non-controlled entities				3,333
Investments at September 30, 2016		$ 523,437		523,437
Equity Method Investment, Summarized Financial Information, Revenue		55,843	47,555	155,067	146,320
Equity Method Investment, Summarized Financial Information, Net Income (Loss)		$ 33,514	28,150	$ 91,981	91,806
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				$ 28,100
All Other Equity Investments [Member]
Change in Equity Method Investments [Roll Forward]
Investments at December 31, 2015				270,361
Additional investment				143,397
Exchange of investment in non-controlled entity				(25,105)
Proportionate share of earnings				7,256
Amortization of excess investment and capitalized interest				(174)
Earnings of non-controlled entities				7,082
Distributions of earnings from investments in non-controlled entities				5,586
Distributions in excess of earnings of non-controlled entities				1,167
Investments at September 30, 2016		$ 388,982		388,982
Equity Method Investment, Summarized Financial Information, Revenue		14,022	12,530	35,451	33,677
Equity Method Investment, Summarized Financial Information, Net Income (Loss)		5,149	4,151	14,907	11,525
Equity Method Investee [Member] | BridgeTex [Member]
Schedule of Equity Method Investments [Line Items]
Related Party Transaction, Other Revenues from Transactions with Related Party		8,900	8,900	26,600	25,800
Accounts Receivable, Related Parties, Current		1,400		1,400
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	$ 800	2,500	$ 2,600
Accounts Receivable, Related Parties, Current		300		300		$ 200
Equity Method Investee [Member] | Powder Springs Logistics, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Accounts Receivable, Related Parties, Current		500		500
Equity Method Investee [Member] | Saddlehorn Pipeline Company [Member]
Schedule of Equity Method Investments [Line Items]
Accounts Receivable, Related Parties, Current		2,900		2,900
Equity Method Investee [Member] | All Other Equity Investments - Construction [Member]
Schedule of Equity Method Investments [Line Items]
Related Party Transaction, Other Revenues from Transactions with Related Party		$ 1,200		$ 2,700