Note 8 - Investments (Details) - Unrealized Gains And Losses (USD $)	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Note 8 - Investments (Details) - Unrealized Gains And Losses [Line Items]
Adjusted Cost	$ 113,858,000	$ 113,687,000
Unrealized Gains	53,000	45,000
Unrealized Losses	(376,000)	(497,000)
Total Fair Value	113,535,000	113,235,000
Fair Value Of Investments In Unrealized Position	14,350,000	25,876,000
Money Market Funds [Member]
Note 8 - Investments (Details) - Unrealized Gains And Losses [Line Items]
Adjusted Cost	9,786,000	15,959,000
Unrealized Gains	0
Unrealized Losses		0
Total Fair Value	9,786,000	15,959,000
US Government Agencies Short-term Debt Securities [Member]
Note 8 - Investments (Details) - Unrealized Gains And Losses [Line Items]
Adjusted Cost	91,852,000	85,483,000
Unrealized Gains	53,000	45,000
Unrealized Losses	(3,000)	(7,000)
Total Fair Value	91,902,000	85,521,000
Fair Value Of Investments In Unrealized Position	4,503,000	14,121,000
Auction Rate Preferred Securities [Member]
Note 8 - Investments (Details) - Unrealized Gains And Losses [Line Items]
Adjusted Cost	12,220,000	12,245,000
Unrealized Losses	(373,000)	(490,000)
Total Fair Value	11,847,000	11,755,000
Fair Value Of Investments In Unrealized Position	$ 9,847,000	$ 11,755,000