Note 8 - Fair Value Measurements (Detail) - Unrealized Gains And Losses (USD $)	Mar. 31, 2013	Dec. 31, 2012
Adjusted Cost	$ 113,745,000	$ 113,687,000
Unrealized Gains	38,000	45,000
Unrealized Losses	(511,000)	(497,000)
Total Fair Value	113,272,000	113,235,000
Fair Value Of Investments In Unrealized Position	27,078,000	25,876,000
Money Market Funds [Member]
Adjusted Cost	19,801,000	15,959,000
Unrealized Gains	0
Unrealized Losses		0
Total Fair Value	19,801,000	15,959,000
US Government Agencies Short-term Debt Securities [Member]
Adjusted Cost	81,724,000	85,483,000
Unrealized Gains	38,000	45,000
Unrealized Losses	(6,000)	(7,000)
Total Fair Value	81,756,000	85,521,000
Fair Value Of Investments In Unrealized Position	15,363,000	14,121,000
Auction Rate Preferred Securities [Member]
Adjusted Cost	12,220,000	12,245,000
Unrealized Losses	(505,000)	(490,000)
Total Fair Value	11,715,000	11,755,000
Fair Value Of Investments In Unrealized Position	$ 11,715,000	$ 11,755,000

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities.

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- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

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- Definition

This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

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