INVESTMENT SECURITIES (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Investment Owned [Abstract]
Cash	$ 2,198	$ 2,153
Cash and cash equivalents	23,546	14,020	12,519	22,829
Marketable securities	62,026	74,666
Long-term investments in ARS	0	3,027
Total cash, cash equivalents, marketable securities and long term investments	85,572	91,713
Available-for-sale Securities [Abstract]
Amortized Cost	85,441	92,522
Gross Unrealized Gains	138	114
Gross Unrealized Losses	(7)	(923)
Fair Market Value	85,572	91,713
Realized Investment Gains (Losses) [Abstract]
Realized gains on investments	19	5	78
Realized losses on investments	0	0	(4)
Investments with Continuous Unrealized Loss Position
Less Than 12 Months, Fair Market Value	5,143	14,686
Less Than 12 Months, Gross Unrealized Losses	(7)	(16)
12 Months or Greater , Fair Market Value	0	10,826
12 Months or Greater, Gross Unrealized Losses	0	(907)
Total Fair Market Value	5,143	25,512
Total Gross Unrealized Losses	(7)	(923)
Estimated fair value of marketable investments and long-term investments classified by contractual maturity date [Abstract]
Due in less than one year (fiscal year 2013)	28,651
Due in 1 to 3 years (fiscal year 2014- 2015)	33,375
Due in 3 to 5 years (fiscal year 2016-2017)	0
Due in 5 to 10 years (fiscal year 2018-2023)	0
Due in greater than 10 years (fiscal year 2024 and beyond)	0
Total	62,026
Short-term Marketable Investments [Abstract]
Available-for-sale securities	85,572	91,713
Long-term Investments [Abstract]
Total assets at fair value	83,374	89,560
Maturity of money market fund	3 months
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	3,027	6,784
Total gains or losses (realized or unrealized) included in other comprehensive loss	262	668
Settlements	(3,289)	(4,425)
Balance, end of period	0	3,027	6,784
Level 1 [Member]
Long-term Investments [Abstract]
Total assets at fair value	17,438	7,318
Level 2 [Member]
Long-term Investments [Abstract]
Total assets at fair value	66,026	79,215
Level 3 [Member]
Long-term Investments [Abstract]
Total assets at fair value	0	3,027
U.S. government notes [Member]
Investment Owned [Abstract]
Marketable securities	4,009	3,665
Available-for-sale Securities [Abstract]
Amortized Cost	4,005	3,655
Gross Unrealized Gains	4	10
Gross Unrealized Losses	0	0
Fair Market Value	4,009	3,665
Short-term Marketable Investments [Abstract]
Available-for-sale securities	4,009	3,665
U.S. government agencies [Member]
Investment Owned [Abstract]
Marketable securities	24,958	41,565
Available-for-sale Securities [Abstract]
Amortized Cost	24,910	41,535
Gross Unrealized Gains	48	44
Gross Unrealized Losses	0	(14)
Fair Market Value	24,958	41,565
Investments with Continuous Unrealized Loss Position
Less Than 12 Months, Fair Market Value	0	12,758
Less Than 12 Months, Gross Unrealized Losses	0	(14)
12 Months or Greater , Fair Market Value	0	0
12 Months or Greater, Gross Unrealized Losses	0	0
Total Fair Market Value	0	12,758
Total Gross Unrealized Losses	0	(14)
Short-term Marketable Investments [Abstract]
Available-for-sale securities	24,958	41,565
Municipal securities [Member]
Investment Owned [Abstract]
Marketable securities	4,206	6,134
Available-for-sale Securities [Abstract]
Amortized Cost	4,184	6,091
Gross Unrealized Gains	23	44
Gross Unrealized Losses	(1)	(1)
Fair Market Value	4,206	6,134
Investments with Continuous Unrealized Loss Position
Less Than 12 Months, Fair Market Value	299	929
Less Than 12 Months, Gross Unrealized Losses	(1)	(1)
12 Months or Greater , Fair Market Value	0	0
12 Months or Greater, Gross Unrealized Losses	0	0
Total Fair Market Value	299	929
Total Gross Unrealized Losses	(1)	(1)
Short-term Marketable Investments [Abstract]
Available-for-sale securities	4,206	6,134
Commercial paper [Member]
Investment Owned [Abstract]
Marketable securities	10,519	4,747
Available-for-sale Securities [Abstract]
Amortized Cost	10,515	4,747
Gross Unrealized Gains	4	1
Gross Unrealized Losses	0	(1)
Fair Market Value	10,519	4,747
Investments with Continuous Unrealized Loss Position
Less Than 12 Months, Fair Market Value	0	999
Less Than 12 Months, Gross Unrealized Losses	0	(1)
12 Months or Greater , Fair Market Value	0	0
12 Months or Greater, Gross Unrealized Losses	0	0
Total Fair Market Value	0	999
Total Gross Unrealized Losses	0	(1)
Short-term Marketable Investments [Abstract]
Available-for-sale securities	10,519	4,747
Corporate debt securities [Member]
Investment Owned [Abstract]
Marketable securities	18,334	18,555
Available-for-sale Securities [Abstract]
Amortized Cost	18,281	18,574
Gross Unrealized Gains	59	15
Gross Unrealized Losses	(6)	(34)
Fair Market Value	18,334	18,555
Investments with Continuous Unrealized Loss Position
Less Than 12 Months, Fair Market Value	4,844	0
Less Than 12 Months, Gross Unrealized Losses	(6)	0
12 Months or Greater , Fair Market Value	0	7,799
12 Months or Greater, Gross Unrealized Losses	0	(34)
Total Fair Market Value	4,844	7,799
Total Gross Unrealized Losses	(6)	(34)
Short-term Marketable Investments [Abstract]
Available-for-sale securities	18,334	18,555
Long-term investments in ARS [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	0	3,900
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	(873)
Fair Market Value	0	3,027
Investments with Continuous Unrealized Loss Position
Less Than 12 Months, Fair Market Value	0	0
Less Than 12 Months, Gross Unrealized Losses	0	0
12 Months or Greater , Fair Market Value	0	3,027
12 Months or Greater, Gross Unrealized Losses	0	(873)
Total Fair Market Value	0	3,027
Total Gross Unrealized Losses	0	(873)
Short-term Marketable Investments [Abstract]
Available-for-sale securities	0	3,027
Long-term Investments [Abstract]
Available for sale ARS	0	3,027
Long-term investments in ARS [Member] | Level 1 [Member]
Long-term Investments [Abstract]
Available for sale ARS	0	0
Long-term investments in ARS [Member] | Level 2 [Member]
Long-term Investments [Abstract]
Available for sale ARS	0	0
Long-term investments in ARS [Member] | Level 3 [Member]
Long-term Investments [Abstract]
Available for sale ARS	0	3,027
Money Market Funds [Member]
Investment Owned [Abstract]
Cash equivalents	17,348	7,318
Cash Equivalents [Abstract]
Money market funds	17,348	7,318
Money Market Funds [Member] | Level 1 [Member]
Cash Equivalents [Abstract]
Money market funds	17,438	7,318
Money Market Funds [Member] | Level 2 [Member]
Cash Equivalents [Abstract]
Money market funds	0	0
Money Market Funds [Member] | Level 3 [Member]
Cash Equivalents [Abstract]
Money market funds	0	0
Commercial Paper [Member]
Investment Owned [Abstract]
Cash equivalents	4,000	4,549
Cash Equivalents [Abstract]
Commercial paper	4,000	4,549
Commercial Paper [Member] | Level 1 [Member]
Cash Equivalents [Abstract]
Commercial paper	0	0
Commercial Paper [Member] | Level 2 [Member]
Cash Equivalents [Abstract]
Commercial paper	4,000	4,549
Commercial Paper [Member] | Level 3 [Member]
Cash Equivalents [Abstract]
Commercial paper	0	0
Cash and Cash Equivalents [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	23,546	14,020
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Market Value	23,546	14,020
Short-term Marketable Investments [Abstract]
Available-for-sale securities	23,546	14,020
Marketable Securities [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	61,895	74,602
Gross Unrealized Gains	138	114
Gross Unrealized Losses	(7)	(50)
Fair Market Value	62,026	74,666
Short-term Marketable Investments [Abstract]
Available-for-sale securities	62,026	74,666
Marketable Securities [Member] | Level 1 [Member]
Available-for-sale Securities [Abstract]
Fair Market Value	0	0
Short-term Marketable Investments [Abstract]
Available-for-sale securities	0	0
Marketable Securities [Member] | Level 2 [Member]
Available-for-sale Securities [Abstract]
Fair Market Value	62,026	74,666
Short-term Marketable Investments [Abstract]
Available-for-sale securities	62,026	74,666
Marketable Securities [Member] | Level 3 [Member]
Available-for-sale Securities [Abstract]
Fair Market Value	0	0
Short-term Marketable Investments [Abstract]
Available-for-sale securities	$ 0	$ 0