QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended												12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	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, 2012	Dec. 31, 2011	Dec. 31, 2010
QUARTERLY FINANCIAL INFORMATION (UNAUDITED) [Abstract]
Total revenue	$ 19,062	$ 20,537	$ 19,981	$ 16,738	$ 17,387	$ 18,187	$ 18,999	$ 18,254	$ 16,525	$ 18,223	$ 17,622	$ 15,571	$ 76,318	$ 72,827	$ 67,941
Net loss	$ (18,952)	$ (41,188)	$ (27,533)	$ (24,525)	$ (33,709)	$ (681)	$ (14,068)	$ (6,466)	$ (18,083)	$ (24,493)	$ (19,249)	$ (35,642)	$ (112,198)	$ (54,924)	$ (97,467)
Basic loss per common share	$ (0.05)	$ (0.1)	$ (0.07)	$ (0.07)	$ (0.11)	$ 0.0	$ (0.05)	$ (0.02)	$ (0.05)	$ (0.09)	$ (0.07)	$ (0.13)	$ (0.29)	$ (0.18)	$ (0.34)
Diluted loss per common share	$ (0.05)	$ (0.1)	$ (0.07)	$ (0.07)	$ (0.11)	$ 0.0	$ (0.05)	$ (0.02)	$ (0.05)	$ (0.09)	$ (0.07)	$ (0.13)	$ (0.29)	$ (0.18)	$ (0.34)
Shares used in basic per share calculations	424,180	392,344	379,433	357,418	312,867	295,513	294,963	293,053	291,818	287,502	282,080	275,370	388,453	299,144	285,316
Shares used in diluted per share calculations	424,180	392,344	379,433	357,418	312,867	295,513	294,963	293,053	291,818	287,502	282,080	275,370	388,453	299,144	285,316