Income Per Share (Summary Of Basic And Diluted Earnings Per Share) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Share [Abstract]
Net income (loss) available to common unitholders	$ (52,288)	$ 109,314	$ 41,510	$ 34,186	$ 42,977	$ 138,872	$ 47,077	$ 42,657	$ 132,718	$ 271,583	$ 171,662
Weighted average units outstanding—basic									133,369,047	127,941,134	115,717,667
Stock options									30,434	61,375	72,818
Unvested incentive units									90,449	125,132	216,092
2014 market performance-based awards									147,305	0	0
Weighted average units outstanding—diluted									133,637,235	128,127,641	116,006,577
Basic, in dollars per share	$ (0.39)	$ 0.81	$ 0.31	$ 0.27	$ 0.33	$ 1.08	$ 0.37	$ 0.34	$ 1.00	$ 2.12	$ 1.48
Diluted, in dollars per share	$ (0.39)	$ 0.80	$ 0.31	$ 0.26	$ 0.33	$ 1.06	$ 0.37	$ 0.34	$ 0.99	$ 2.12	$ 1.48