Equity and Distributions, Distributions (Details) - Cash Distribution [Member] - $ / shares	6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2018
First Quarter 2017 Distribution [Member]
Distributions to Partners [Abstract]
Distribution Per Common Unit (in dollars per unit)		$ 0.4150
Record Date		Apr. 28, 2017
Payment Date		May 08, 2017
Second Quarter 2017 Distribution [Member]
Distributions to Partners [Abstract]
Distribution Per Common Unit (in dollars per unit)		$ 0.4200
Record Date	Jul. 31, 2017
Payment Date	Aug. 07, 2017
First Quarter 2018 Distribution [Member]
Distributions to Partners [Abstract]
Distribution Per Common Unit (in dollars per unit)	$ 0.4275
Record Date	Apr. 30, 2018
Payment Date	May 08, 2018
Second Quarter 2018 Distribution [Member]
Distributions to Partners [Abstract]
Distribution Per Common Unit (in dollars per unit)	$ 0.4300
Record Date	Jul. 31, 2018
Payment Date	Aug. 08, 2018
Forecast [Member] | Third Quarter 2018 Distribution [Member]
Distributions to Partners [Abstract]
Distribution Per Common Unit (in dollars per unit)			$ 0.4325
Forecast [Member] | Fourth Quarter 2018 Distribution [Member]
Distributions to Partners [Abstract]
Distribution Per Common Unit (in dollars per unit)			$ 0.4350