FAIR VALUE OF CERTAIN FINANCIAL ASSETS AND LIABILITIES (Details 4) (USD $)	3 Months Ended	12 Months Ended				12 Months Ended			12 Months Ended
	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2010	Dec. 31, 2011	Dec. 31, 2012 Auction rate securities	Dec. 31, 2012 2011 ARS Agreement	Dec. 31, 2011 2011 ARS Agreement	Jun. 30, 2011 2011 ARS Agreement	Dec. 31, 2011 2010 ARS Agreement	Mar. 31, 2010 2010 ARS Agreement	Dec. 31, 2012 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					$ 27,800,000
Amortized Cost		115,952,000		434,476,000	20,700,000
Fair value of available-for-sale securities					5,800,000
Impairment of investments available-for-sale					2,500,000
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						1,300,000	3,700,000		38,500,000
Fair market value of investments											1,900,000
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 income	$ (800,000)	$ 800,000	$ (800,000)