FAIR VALUE (DETAILS) (USD $) In Thousands, unless otherwise specified			3 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2012 Auction Rate Securities [Member]	Mar. 31, 2012 Fair Value Inputs Level 1 [Member]	Dec. 31, 2011 Fair Value Inputs Level 1 [Member]	Mar. 31, 2012 Fair Value Inputs Level 2 [Member]	Dec. 31, 2011 Fair Value Inputs Level 2 [Member]	Mar. 31, 2012 Fair Value Inputs Level 3 [Member]	Dec. 31, 2011 Fair Value Inputs Level 3 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Corporate Debt Securities Fair Value Disclosure	$ 132,726	$ 138,166		$ 0	$ 0	$ 132,726	$ 138,166	$ 0	$ 0
US Treasury And Government Fair Value Disclosure	111,588	125,289		0	0	111,588	125,289	0	0
Auction Rate Securities Fair Value Disclosure	12,754	12,793		0	0	0	0	12,754	12,793
Asset Backed Securities Fair Value Disclosure	9,159	9,519		0	0	9,159	9,519	0	0
Total Assets Measured At Fair Value	266,227	285,767		0	0	253,473	272,974	12,754	12,793
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement With Unobservable Inputs Reconciliation, Recurring Basis, Asset Value, Beginning Balance			12,793
Transfers To (From) Level 3			0
Total Gains (Losses) Included In Other (Income) Expense, Net			0
Total Gains Included In Other Comprehensive Income			11
Purchases			0
Settlements			(50)
Fair Value, Measurement With Unobservable Inputs Reconciliation, Recurring Basis, Asset Value, Ending Balance			$ 12,754