FAIR VALUE MEASUREMENT (Details) (USD $)	4 Months Ended	12 Months Ended			88 Months Ended
	Dec. 31, 2012	Aug. 31, 2012	Aug. 31, 2011	Aug. 31, 2010	Dec. 31, 2012
Warrant liabilities activity [Abstract]
Change in fair value recognized in earnings	$ 1,500,000	$ 3,200,000	$ 16,300,000	$ 5,900,000	$ 26,900,000
- 10% Change in Stock Price [Member]
Warrant liabilities activity [Abstract]
(Increase) decrease in net loss	2,000,000
+ 10% Change in Stock Price [Member]
Warrant liabilities activity [Abstract]
(Increase) decrease in net loss		2,000,000
- 10% Change in Volatility [Member]
Warrant liabilities activity [Abstract]
(Increase) decrease in net loss	700,000
+ 10% Change in Volatility [Member]
Warrant liabilities activity [Abstract]
(Increase) decrease in net loss	700,000
Recurring [Member]
Assets [Abstract]
Fair value of assets	57,165,000	28,469,000	13,856,000		57,165,000
Liabilities [Abstract]
Fair value of liabilities	16,405,000	17,266,000	23,575,000		16,405,000
Warrant liabilities activity [Abstract]
Warrant liability at end of period	16,405,000	17,266,000	23,575,000		16,405,000
Recurring [Member] | Common Stock Warrants [Member]
Liabilities [Abstract]
Fair value of liabilities	16,405,000	17,266,000	23,575,000		16,405,000
Warrant liabilities activity [Abstract]
Warrant liability at end of period	16,405,000	17,266,000	23,575,000		16,405,000
Recurring [Member] | Cash Equivalents [Member]
Assets [Abstract]
Fair value of assets	35,069,000	13,162,000	13,856,000		35,069,000
Recurring [Member] | Short-term Investments [Member]
Assets [Abstract]
Fair value of assets	22,096,000	15,307,000	0		22,096,000
Level 1 [Member] | Recurring [Member]
Assets [Abstract]
Fair value of assets	57,165,000	28,469,000	13,856,000		57,165,000
Liabilities [Abstract]
Fair value of liabilities	0	0	0		0
Warrant liabilities activity [Abstract]
Warrant liability at end of period	0	0	0		0
Level 1 [Member] | Recurring [Member] | Common Stock Warrants [Member]
Liabilities [Abstract]
Fair value of liabilities	0	0	0		0
Warrant liabilities activity [Abstract]
Warrant liability at end of period	0	0	0		0
Level 1 [Member] | Recurring [Member] | Cash Equivalents [Member]
Assets [Abstract]
Fair value of assets	35,069,000	13,162,000	13,856,000		35,069,000
Level 1 [Member] | Recurring [Member] | Short-term Investments [Member]
Assets [Abstract]
Fair value of assets	22,096,000	15,307,000	0		22,096,000
Level 2 [Member] | Recurring [Member]
Assets [Abstract]
Fair value of assets	0	0	0		0
Liabilities [Abstract]
Fair value of liabilities	0	0	0		0
Warrant liabilities activity [Abstract]
Warrant liability at end of period	0	0	0		0
Level 2 [Member] | Recurring [Member] | Common Stock Warrants [Member]
Liabilities [Abstract]
Fair value of liabilities	0	0	0		0
Warrant liabilities activity [Abstract]
Warrant liability at end of period	0	0	0		0
Level 2 [Member] | Recurring [Member] | Cash Equivalents [Member]
Assets [Abstract]
Fair value of assets	0	0	0		0
Level 2 [Member] | Recurring [Member] | Short-term Investments [Member]
Assets [Abstract]
Fair value of assets	0	0	0		0
Level 3 [Member] | Common Stock Warrants [Member]
Liabilities [Abstract]
Fair value of liabilities	16,405,000	17,266,000	23,575,000		16,405,000
Warrant liabilities activity [Abstract]
Fair value of warrants at beginning of period	17,266,000	23,575,000	15,780,000
Change in fair value recognized in earnings	1,484,000	3,173,000	16,301,000
Exercises	(2,345,000)	(9,482,000)	(8,506,000)
Warrant liability at end of period	16,405,000	17,266,000	23,575,000		16,405,000
Level 3 [Member] | Recurring [Member]
Assets [Abstract]
Fair value of assets	0	0	0		0
Liabilities [Abstract]
Fair value of liabilities	16,405,000	17,266,000	23,575,000		16,405,000
Warrant liabilities activity [Abstract]
Warrant liability at end of period	16,405,000	17,266,000	23,575,000		16,405,000
Level 3 [Member] | Recurring [Member] | Common Stock Warrants [Member]
Liabilities [Abstract]
Fair value of liabilities	16,405,000	17,266,000	23,575,000		16,405,000
Warrant liabilities activity [Abstract]
Warrant liability at end of period	16,405,000	17,266,000	23,575,000		16,405,000
Level 3 [Member] | Recurring [Member] | Cash Equivalents [Member]
Assets [Abstract]
Fair value of assets	0	0	0		0
Level 3 [Member] | Recurring [Member] | Short-term Investments [Member]
Assets [Abstract]
Fair value of assets	$ 0	$ 0	$ 0		$ 0