Note 8 - Fair Value Measurements (Detail) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011	Dec. 31, 2009	Jun. 30, 2012	Mar. 31, 2012	Dec. 30, 2011
Available-for-sale Securities	$ 107,300,000		$ 107,300,000
Deposits, Money Market Deposits	27,100,000		27,100,000		51,100,000
Trading Securities, Change in Unrealized Holding Gain (Loss)			40,000		17,000
Auction Rate Securities, Noncurrent	11,756,000		11,756,000		13,675,000		11,714,000	13,665,000	13,675,000
Cash Equivalents, at Carrying Value					2,000,000
Other than Temporary Impairment Losses, Investments	(42,000)	(150,000)	(141,000)	(290,000)	700,000
Trading Securities, Realized Gain (Loss)						70,000
Cash Flow Model Input Time To Liquidity	24		24		24
Cash Flow Model Input Expected Return	1.80%		1.80%		1.80%
Money Market Funds [Member]
Trading Securities, Change in Unrealized Holding Gain (Loss)			9,000
Government Backed Securities [Member]
Auction Rate Securities, Noncurrent	11,800,000		11,800,000
Face Value [Member]
Auction Rate Securities, Noncurrent	12,300,000		12,300,000
Auction Rate Securities Backed By Student-Loan Notes [Member]
Other than Temporary Impairment Losses, Investments			520,000
Temporary [Member]
Other than Temporary Impairment Losses, Investments			490,000		600,000
Other Than Temporary [Member]
Other than Temporary Impairment Losses, Investments			30,000		100,000
Moodys AAA [Member]
Auction Rate Securities, Noncurrent						6.0
Moodys A3 To Baa3 [Member]
Auction Rate Securities, Noncurrent						6,300,000
Government Backed Securities [Member]
Available-for-sale Securities, Current					77,800,000
Auction Rate Securities [Member]
Auction Rate Securities, Noncurrent					$ 14,400,000