Equity (Distributions) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2017	Mar. 31, 2017	Mar. 31, 2016	Jun. 30, 2017
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared		$ 28,783
Incentive Distribution, Distribution		2,147	$ 761
Distribution Made to Limited Partner, Cash Distributions Paid		26,636	18,549
Partners' Capital Account, Distributions		$ 28,783	$ 19,620
Distribution Made to Limited Partner, Distributions Declared, Per Unit		$ 0.4375	$ 0.3925
Subsequent Event [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distribution Made to Limited Partner, Distributions Declared, Per Unit	$ 0.4525			$ 0.8900
TexNew Mex Units [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared		$ 0
Distribution Made to Limited Partner, Cash Distributions Paid		0	$ 310
Common Units [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared		16,657	9,595
Distribution Made to Limited Partner, Cash Distributions Paid		16,657	9,595
Subordinated Units [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared		9,979	8,954
Distribution Made to Limited Partner, Cash Distributions Paid		$ 9,979	$ 8,954