SHARE-BASED COMPENSATION - RSU Activity - Summary of Change (Details) (USD $)	12 Months Ended
	Dec. 31, 2012 number	Dec. 31, 2011	Dec. 31, 2010
Number of Restricted Stock Units [Roll Forward]
RSUs beginning	1,860,577
RSUs awarded	306,556	445,000	1,024,000
RSUs released	(659,381)	(886,000)	(527,000)
RSUs forfeited	(26,484)	(28,000)	(85,000)
RSUs ending	1,481,268	1,860,577
Weighted Average Purchase Price RSUs	$ 0
Weighted Average Remaining Contractual Term (Years) RSUs	1.1
Aggregate Intrinsic Value RSUs	$ 10,339,251
Number of RSUs vested and expected to vest	1,388,230
Weighted Average Purchase Price of RSUs vested and expected to vest	$ 0
Weighted Average Remaining Contractual Term (Years) of RUSs vested and expected to vest	1.1
Aggregate Intrinsic Value RSUs vested and expected to vest	9,082,613
Number of RSUs exercisable	86,996
Weighted Average Purchase Price of RUSs exercisable	$ 0
Weighted Average Remaining Contractual Term (Years) of RUSs exercisable	0.0
Aggregate Intrinsic Value RSUs exercisable	607,232
Weighted average remaining recognition period in years	1.9
Unamortized compensation expense, net of estimated forfeitures	$ 5,714,641