Equity (Distributions) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended		9 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Sep. 30, 2016
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Incentive Distribution, Distribution		$ 921		$ 139	$ 1,682	$ 155
Distribution Made to Limited Partner, Cash Distributions Paid		19,039		16,273	37,588	31,832
Partners' Capital Account, Distributions		$ 19,960		$ 16,412	$ 39,580	$ 31,987
Distribution Made to Limited Partner, Distributions Declared, Per Unit		$ 0.4025	$ 0.3925	$ 0.3475	$ 0.7950	$ 0.6800
Subsequent Event [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distribution Made to Limited Partner, Distributions Declared, Per Unit	$ 0.4125						$ 1.2075
TexNew Mex Units [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distribution Made to Limited Partner, Cash Distributions Paid		$ 0		$ 0	$ 310	$ 0
Common Units [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distribution Made to Limited Partner, Cash Distributions Paid		9,858		8,346	19,453	16,320
Subordinated Units [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distribution Made to Limited Partner, Cash Distributions Paid		$ 9,181		$ 7,927	$ 18,135	$ 15,512