Partners' Capital and Distributions (Schedule Of Distributions) (Details) - USD ($) $ / shares in Units, $ in Thousands									9 Months Ended		12 Months Ended
	Nov. 13, 2020	Aug. 14, 2020	May 15, 2020	Feb. 14, 2020	Nov. 14, 2019	Aug. 14, 2019	May 15, 2019	Feb. 14, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2020	Dec. 31, 2019
Distribution Made to Limited Partner [Line Items]
Cash distribution per unit (in dollars per share)		$ 1.0275	$ 1.0275	$ 1.0275	$ 1.0200	$ 1.0125	$ 1.0050	$ 0.9975	$ 3.0825	$ 3.0150		$ 4.0350
Total Cash Distribution to Limited Partners		$ 231,245	$ 231,245	$ 234,774	$ 232,971	$ 231,258	$ 229,545	$ 227,832	$ 697,264	$ 688,635		$ 921,606
Scenario, Forecast
Distribution Made to Limited Partner [Line Items]
Cash distribution per unit (in dollars per share)	$ 1.0275										$ 4.1100
Total Cash Distribution to Limited Partners	$ 229,853										$ 927,117