Equity Investments - Equity Investments Table (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Balance	$ 1,092,088	$ 817,352
Acquisitions	92,546	162,615
Equity income, net	237,518	195,469	$ 115,141
Contributions	128,393	133,629	2,884
Distributions	(234,572)	(187,392)	(117,093)
Distributions in excess of cumulative earnings	(30,256)	(29,585)	(31,659)
Balance	1,285,717	1,092,088	817,352
Fort Union [Member]
Schedule of Equity Method Investments [Line Items]
Balance	2,259	7,030
Acquisitions	0	0
Equity income, net	(2,232)	(1,433)
Contributions	0	0
Distributions	0	(194)
Distributions in excess of cumulative earnings	(637)	(3,144)
Balance	(610)	2,259	7,030
White Cliffs [Member]
Schedule of Equity Method Investments [Line Items]
Balance	43,020	44,945
Acquisitions	0	0
Equity income, net	9,500	11,841
Contributions	5,414	1,278
Distributions	(8,918)	(11,259)
Distributions in excess of cumulative earnings	(3,139)	(3,785)
Balance	45,877	43,020	44,945
Rendezvous [Member]
Schedule of Equity Method Investments [Line Items]
Balance	37,841	42,528
Acquisitions	0	0
Equity income, net	769	767
Contributions	0	0
Distributions	(2,710)	(2,709)
Distributions in excess of cumulative earnings	(2,936)	(2,745)
Balance	32,964	37,841	42,528
Mont Belvieu JV [Member]
Schedule of Equity Method Investments [Line Items]
Balance	104,949	110,299
Acquisitions	0	0
Equity income, net	28,412	29,200
Contributions	0	0
Distributions	(28,451)	(29,239)
Distributions in excess of cumulative earnings	(1,874)	(5,311)
Balance	103,036	104,949	110,299
Texas Express Gathering [Member]
Schedule of Equity Method Investments [Line Items]
Balance	19,358	15,879
Acquisitions	0	0
Equity income, net	4,088	4,290
Contributions	0	3,720
Distributions	(4,110)	(4,368)
Distributions in excess of cumulative earnings	(1,137)	(163)
Balance	18,199	19,358	15,879
Texas Express Pipeline [Member]
Schedule of Equity Method Investments [Line Items]
Balance	193,198	178,975
Acquisitions	0	0
Equity income, net	30,871	37,963
Contributions	12,220	11,980
Distributions	(32,733)	(33,552)
Distributions in excess of cumulative earnings	0	(2,168)
Balance	203,556	193,198	178,975
Front Range Pipeline [Member]
Schedule of Equity Method Investments [Line Items]
Balance	176,436	166,555
Acquisitions	0	0
Equity income, net	32,617	23,308
Contributions	30,175	14,980
Distributions	(31,446)	(23,481)
Distributions in excess of cumulative earnings	0	(4,926)
Balance	207,782	176,436	166,555
Whitethorn LLC [Member]
Schedule of Equity Method Investments [Line Items]
Balance	161,858	0
Acquisitions	0	150,563
Equity income, net	74,548	47,088
Contributions	10,332	7,069
Distributions	(74,856)	(39,497)
Distributions in excess of cumulative earnings	(10,217)	(3,365)
Balance	161,665	161,858	0
Cactus II [Member]
Schedule of Equity Method Investments [Line Items]
Balance	106,360	0
Acquisitions	0	12,052
Equity income, net	10,755	0
Contributions	56,252	94,308
Distributions	(1,202)	0
Distributions in excess of cumulative earnings	0	0
Balance	172,165	106,360	0
Capitalized interest	3,600	1,400
Saddlehorn [Member]
Schedule of Equity Method Investments [Line Items]
Balance	108,507	109,227
Acquisitions	0	0
Equity income, net	25,524	15,833
Contributions	3,550	294
Distributions	(24,726)	(16,017)
Distributions in excess of cumulative earnings	0	(830)
Balance	112,855	108,507	109,227
Panola [Member]
Schedule of Equity Method Investments [Line Items]
Balance	22,769	23,625
Acquisitions	0	0
Equity income, net	2,136	2,200
Contributions	0	0
Distributions	(2,137)	(2,200)
Distributions in excess of cumulative earnings	(985)	(856)
Balance	21,783	22,769	23,625
Mi Vida [Member]
Schedule of Equity Method Investments [Line Items]
Balance	64,631	64,988
Acquisitions	0	0
Equity income, net	10,655	13,734
Contributions	0	0
Distributions	(12,077)	(14,000)
Distributions in excess of cumulative earnings	(5,402)	(91)
Balance	57,807	64,631	64,988
Ranch Westex [Member]
Schedule of Equity Method Investments [Line Items]
Balance	50,902	53,301
Acquisitions	0	0
Equity income, net	6,812	10,678
Contributions	0	0
Distributions	(8,143)	(10,876)
Distributions in excess of cumulative earnings	(2,893)	(2,201)
Balance	46,678	50,902	$ 53,301
Red Bluff Express [Member]
Schedule of Equity Method Investments [Line Items]
Balance	0
Acquisitions	92,546
Equity income, net	3,063
Contributions	10,450
Distributions	(3,063)
Distributions in excess of cumulative earnings	(1,036)
Balance	$ 101,960	$ 0