Partners' Capital and Distributions (Distributions) (Details) - USD ($) $ / shares in Units, $ in Thousands	Feb. 14, 2017	Nov. 14, 2016	Aug. 12, 2016	May 13, 2016	Feb. 12, 2016	Nov. 13, 2015	Aug. 14, 2015	May 15, 2015	Feb. 13, 2015	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015
Distribution Made to Limited Partner [Line Items]
Per Unit Amount (in dollars per share)		$ 0.7000	$ 0.6900	$ 0.6725	$ 0.6550	$ 0.6400	$ 0.6250	$ 0.6100	$ 0.5950	$ 0.7000	$ 0.6900	$ 0.6725	$ 0.6550	$ 0.6400	$ 0.6250	$ 0.6100	$ 0.5950
Total Amount		$ 82,585	$ 81,406	$ 73,961	$ 72,036	$ 70,387	$ 68,737	$ 60,774	$ 56,542
Subsequent Event [Member]
Distribution Made to Limited Partner [Line Items]
Per Unit Amount (in dollars per share)	$ 0.7100
Total Amount	$ 83,765