Note 8 - Fair Value Measurements (Details) - Current Assets Fair Market Value (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash in banks	$ 85,994	$ 59,145
Money market funds	15,741	15,959
US treasuries and US government agency bonds	87,884	85,521
Total cash, cash equivalents and investments	201,317	172,380
Auction Rate Securities Backed By Student-Loan Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Auction-rate securities backed by student-loan notes	$ 11,698	$ 11,755

- Definition

Cash includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the customer may deposit additional funds at any time and effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid Investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Investments includes Short Term and Long Term, exclusive of cash equivalents, generally consist of marketable securities intended to be sold within one year (Short Term) or held longer than one year (Long Term) (or the normal operating cycle if longer) and may include trading securities, available-for-sale securities, or held-to-maturity securities (if maturing within one year), as applicable.

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