Quarterly Financial Data (Summary Of Quarterly Financial Data) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Data [Abstract]
Revenues	$ 491,011	$ 572,334	$ 656,327	$ 526,857	$ 847,282	$ 964,114	$ 1,015,049	$ 1,019,719	$ 2,246,529	$ 3,846,164	$ 4,134,830
Operating income (loss)	57,870	44,798	29,380	24,819	30,624	35,268	31,257	35,402	156,867	132,551	110,757
Income from continuing operations before income taxes									425,572	109,047	84,849
Income from continuing operations	26,296	363,409	11,665	20,215	26,166	29,113	21,148	29,775	421,585	106,202	84,004
Net Income (Loss) Attributable to Noncontrolling Interest	1,138	(195)	0	0					943	0	0
Net Income (Loss) Attributable to Parent	$ 27,434	$ 363,214	$ 11,665	$ 20,215					422,528	106,202	86,109
Income from discontinued operations									0	0	2,105
Net income (loss)					$ 26,166	$ 29,113	$ 21,148	$ 29,775	$ 421,585	$ 106,202	$ 86,109
Income (Loss) from Continuing Operations, Per Outstanding Limited Partnership Unit, Basic, Net of Tax	$ 0.24	$ 3.38	$ 0.12	$ 0.21	$ 0.28	$ 0.33	$ 0.24	$ 0.34
Net income per common unit-basic and diluted	0.24	3.38	0.12	0.21	0.28	0.33	0.24	0.34
Per Unit Amount	$ 0.6400	$ 0.6250	$ 0.6100	$ 0.5950	$ 0.5800	$ 0.5650	$ 0.5500	$ 0.5350	$ 0.6400	$ 0.5800