MARKETABLE SECURITIES (Details 1) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012 security	Sep. 30, 2011	Sep. 30, 2012 security	Sep. 30, 2011	Dec. 31, 2011
Continuous unrealized loss position
Fair Value	$ 5,895,000		$ 5,895,000		$ 24,631,000
Gross Unrealized Losses	(2,000)		(2,000)		(37,000)
Proceeds from maturities and sales of current and non-current available-for-sale marketable securities and related gross realized gains and losses
Proceeds from maturities and sales of available-for-sale marketable securities	40,570,000	128,287,000	88,347,000	542,191,000
Gross realized gains	241,000	387,000	2,039,000	2,303,000
Gross realized losses				(18,000)
Net unrealized gains, net of tax, reclassified from other comprehensive income into earnings	100,000	600,000	900,000	2,000,000
Number of investments in continuous unrealized loss position for less than 12 months	3		3
Corporate debt securities
Continuous unrealized loss position
Fair Value					12,920,000
Gross Unrealized Losses					(15,000)
States of the U.S. and state political subdivisions
Continuous unrealized loss position
Fair Value	5,895,000		5,895,000		11,711,000
Gross Unrealized Losses	$ (2,000)		$ (2,000)		$ (22,000)