Distributions (Schedule Of Distributions) (Details) - USD ($) $ / shares in Units, $ in Thousands									9 Months Ended		12 Months Ended
	Nov. 14, 2016	Aug. 12, 2016	May 13, 2016	Feb. 12, 2016	Nov. 13, 2015	Aug. 14, 2015	May 15, 2015	Feb. 13, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2016	Dec. 31, 2015
Per Unit Cash Distribution Amount		$ 0.8200	$ 0.8025	$ 0.785	$ 0.7625	$ 0.7400	$ 0.7175	$ 0.6950	$ 2.4075	$ 2.1525		$ 2.915
Total Cash Distribution to Limited Partners		$ 186,783	$ 182,797	$ 178,808	$ 173,413	$ 168,296	$ 163,178	$ 158,061	$ 548,388	$ 489,535		$ 662,948
Scenario, Forecast
Per Unit Cash Distribution Amount	$ 0.8375										$ 3.245
Total Cash Distribution to Limited Partners	$ 190,769										$ 739,157