FAIR VALUE OF CERTAIN FINANCIAL ASSETS AND LIABILITIES (Details 4) (USD $)	3 Months Ended				3 Months Ended	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Mar. 31, 2013 Auction rate securities	Mar. 31, 2013 2011 ARS Agreement	Dec. 31, 2012 2011 ARS Agreement	Dec. 31, 2011 2011 ARS Agreement	Jun. 30, 2011 2011 ARS Agreement	Mar. 31, 2010 2010 ARS Agreement	Mar. 31, 2013 2011 Put Option	Oct. 02, 2013 2011 Put Option Maximum	Jul. 02, 2013 2011 Put Option Maximum	Mar. 31, 2012 2010 Put Option
ARS Agreement
Face value of investments				$ 19,500,000
Amortized Cost	115,770,000		115,952,000	17,400,000
Trading auction rate securities, in short-term and long-term investments				17,400,000
Impairment of investments, trading securities				2,100,000
Amount of securities of par value								24,500,000	54,200,000		1,000,000	1,000,000
Redemption of investment securities at par through normal market channels					0	1,300,000	3,700,000
Fair market value of investments										2,000,000
Redemption of investment securities through the exercise of the put option													15,700,000
Resulted gain or loss on revaluation of investment securities included in other (expense) income	$ 2,600,000	$ 400,000