MARKETABLE SECURITIES (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Continuous unrealized loss position for less than twelve months
Fair Value	$ 43,219		$ 43,219		$ 73,723
Gross Unrealized Losses	(107)		(107)		(246)
Proceeds from maturities and sales of available-for-sale marketable securities and related gross realized gains and losses
Proceeds from maturities and sales of available-for-sale marketable securities	128,287	240,584	542,191	612,452
Gross realized gains	387	328	2,303	4,660
Gross realized losses			(18)	(7)
Corporate debt securities
Continuous unrealized loss position for less than twelve months
Fair Value	16,995		16,995		34,552
Gross Unrealized Losses	(41)		(41)		(16)
States of the U.S. and state political subdivisions
Continuous unrealized loss position for less than twelve months
Fair Value	26,224		26,224		39,171
Gross Unrealized Losses	$ (66)		$ (66)		$ (230)