Condensed Quarterly Financial Data (Schedule Of Quarterly Financial Data) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Condensed Quarterly Financial Data [Abstract]
Total revenues	$ 48,887	$ 20,666	$ 13,054	$ 12,171	$ 8,146	$ 15,991	$ 36,878	$ 46,455	$ 94,778	$ 107,470	$ 51,965
Net income (loss)	$ (27,165)	$ (40,685)	$ (51,506)	$ (32,674)	$ (34,546)	$ (34,856)	$ (8,323)	$ 11,460	$ (152,030)	$ (66,265)	$ (81,683)
Net income (loss) per share-basic and diluted	$ (0.24)	$ (0.35)	$ (0.45)	$ (0.30)	$ (0.34)	$ (0.34)	$ (0.08)	$ 0.11	$ (1.34)	$ (0.66)	$ (0.90)